Now we are getting into the pointy end of sailing. No pun intended... I do like intelligent discussion about yacht design. This will be an amazing series. The sailing Adventures are great, but with a crap design, it will never be amazing... You will have to install hydro brakes on the rudders to slow the cat for fishing. I don't know what the success rate of catching fish, using a lure will be at 20 knots...
For anyone interested in what the actual difference would be, because the video just says stuff like "only 5-15 degrees less height upwind and some increased drag" means, 2 boats, identical in every way, using the numbers quoted, say 15 degrees less height upwind in medium air with mild chop. Without taking into account other inefficiencies from mini keels in way of ventilation etc (and other real world things). A boat with decent daggerboards setup right will do, say 10 knots boat speed in 15 knots of breeze at 50 degrees, thats a true VMG of 6.43 knots. (Velocity made good upwind). As opposed to literally an identical boat with mini keels does 8.5 knots (due to added drag and reduced lift) at 65 degrees (because it isnt pointing as high and is making leeway due to reduced lift also dropping apparent wind) in the same 15 knots of breeze, means it's doing 3.59 VMG. Thats literally half the speed to your destination upwind. If your destination was exactly upwind 50 nautical miles it would take 7 hours 46 minutes with the daggerboard boat and with mini keels that would take almost 14 hours.
Very good example! I would say daggerboards are ESSENTIAL on a performance or performance cruising cat. You don't even need 2 x daggerboards, you can have a single larger one, which reduces build cost complexity, maintenance and reduction in interior livable volume.
Thanks for a practical example. I've always heard that most crusing is downwind, but maybe that's from monohull sailors. How often do you end up cruising upwind? (Of course if you had daggerboards, you might go upwind more often.)
Loanword Eggcorn Exactly... I think most cruising is downwind because it’s more comfortable and much easier, and in turn the cheapest location to purchase a used sailboat is at downwind locations, ie. southern Carribbean.
Simply here to learn some aerodynamics. This numerical example makes it easy to understand. So, the difference is roughly [cos(theta) / cos(theta + delta_theta)]^2 . Quite big indeed.
We know from experience that it's one thing to be able to speak fluently in a second language, but it's another thing entirely to be able to translate jargon from a niche field of expertise from one language to another. He did an amazing job!
@@sailingrubyrose Formidable. I noticed on another TH-cam video that a heavy accent (Antone's is not bad at all) and a bad microphone made it impossible. But a heavy accent and a good microphone - no problem.
Regardless, I wish you permitted Antone more time to explain what he was telling us , since ruby rose interrupted too often with personal assumptions. ..imo
Great to hear a naval architect's viewpoint. There's one key thing he said that you didn't emphasise - daggerboards start working at much slower boat speeds, because they're high aspect ratio, like glider wings. You can't get this slow-speed lift from hull shape, or mini keels, as they're all low aspect ratio lift devices, and they only start working at higher speeds through the water. If you want to sail almost all the time, including upwind in light airs, you need daggerboards. If you want to be sure of getting home, without relying on the engine, you need daggerboards. If you're on a lee shore, and need to point your way out of trouble, you need daggerboards. And they make the sailing more fun, if you can stand the extra space and complexity!
It's the other way around. Dagger boards don't work at low speeds and start to work when they reach their optimum speed capability according to their design - chord measurement etc.
@@robertcain3426 I disagree. From personal experience I can tell you that daggerboards at low speeds can make a radical difference in pointing ability vs mini keels.
My experience in racing my cruising cat with one large daggerboard against cats with keels showed that daggerboards are far superior not just for pointing but for vmg also. My boat will point with Farr 40 and sail a bit faster, sail 5 degrees lower and I blow them away. There is no need for two boards, the boat doesn't heel or know which tack it is on, assuming the board is vertical. One other point, if you run aground with both mini keeps good luck getting off. Go to any cruising anchorage and see how cautious the keeled cats are about depth, more than the monos.
One thing he kept saying, but Nick goes right past because he's hung on pointing, is that you get so much more flexibility on other points of sail with being able to REDUCE the amount of drag in the water (raise the boards) when lateral drift is less of a factor. So with dagger boards, you get the best of all worlds as it pertains to performance, higher pointing into the wind, and faster going away = better VMG at all points of sail.
Ok , here's my two bobs worth On my 45ft cat l have 250mm mini keels mainly to protect the rudders when l beach her BUT l also have a swing centre board & l can say it does make a MASSIVE difference in pointing when it's down....best of both worlds...cheers
Sounds like the result of the conversation was that it’s better to have daggerboards! It would be nice if the 1370 had a daggerboard option for those who think pointing higher and having a shallow draft are important.
The problem is striking a balance between performance and livability. If there's one thing I've learned from being around boats and watching all of these sailing video's is that there's always SOMETHING to do/fix and the less crap you have to deal with, the more time you actually have for... you know... living ;). Considering most cruising cats are about the destination vs. the journey, it seems to me the tradeoff is worthwhile. Especially given that the 1370 is a performance oriented cat to begin with. From a practical perspective, the 1370 will already do circles around many other production cats. Anyway, always interested in opinions from those who know much more about this than me as I'm still learning.
@@brois841 Some boats put the daggerboard trunks up against the outer hull, and the intrusion into (and reduction of) living space is almost not noticeable. For a true performance boat, daggerboards would be beneficial.
5º to 15º is a lot! 2 to 3 knots down wind is a lot! I need daggerboards in my catamaran! In the inter tropics zone where the wind is soft this is very important, is the difference between use or not use diesel.
I have owned a Lagoon 380 with minikeels and a 38' cat with daggerboards. The 380 was a good sailer by Lagoon standards bit still made a lot of leeway close hauled. The mini-keels stall at a much higher speed than a daggerboard and at that point you can feel the boat slipping sideways and the increased the drag of the keels slows you down. You have to be very aware of this effect and try to keel the keels efficient for a long as possible even if it means bearing away a little. It was still fun to sail the Lagoon but virtually impossible to prevent significant leeway. We could do about 7.5 knots tacking through effectivly 120-130 degrees with leeway. Most modern cruising monohulls of similar length would easily outsail us to windward. The daggerboard cat was completely different. In effect it is almost impossble to stall the keels and the leeway was imperceptible. She was also much lighter than the Lagoon so at 10 knots boat speed and tacking through 100 degrees, very few cruising monohulls could catch us. Downwind you can partially or completely retract the daggerboards which reduces drag and increases speed. It is a similar concept to folding vs fixed props. So in summary the daggerboard cat performed better in all points of sail and was a lot of fun to play with. Granted that some of that performance advantage was down to weight too. But both types of boats had their strengths and weaknesses, and as ever, it all depends on what you enjoy about sailing. My ideal cat has Lagoon type comfort with centreboards. John Shuttleworth has done some excellent technical papers on centreboards.
Nice vid on theoretics guys! Remember tho the beauty of daggers is that you can RETRACT. We only use our dagger boards when hard on the wind, which is maybe 5% of our sailing and the rest of the time we have clean and fast hulls, without dragging around mini keels...
Having sailed a 53 foot cat for 13 years it's pretty clear that dagger boards, hull shape, bridge deck clearance, sail plan and rig tension ALL play a significant role in sailing performance. The best way to demonstrate this to yourself is to get out on a dagger board cat in flat water (wave action confuses the result) set sail hard to windward dagger board up, push the windward board down, note the wake. Push the leeward board down note the wake. Next check the course made good to windward. Go sailing beach cats with and without dagger boards. It becomes patently obvious that dagger boards wind hands down in sailing ability, BUT that's not all. In shallow anchorages having dagger boards and retractable rudders is a MASSIVE bonus. Hiding from foul weather etc. My boat was built in the 80s, was in commercial survey and would out sail production FRP mini keel cats 20 years younger. So why am I telling you this ? Sailing to windward is going to happen, when you least want to but necessity will mandate that you do. A boat that sails well, into the wind, off the wind, is safer and will get you out of trouble when she needs to. A friend of mine has a Bob Oram 60ft cat that he bought with a single dagger board and retracting rudders, he sailed a lot on my boat and eventually installed a second dagger board on his Oram 60. MUCH more controllable for such a fast light displacement boat.
I think an important factor also is how you primarily are going to use the boat. When living on board I think there is a peace of mind about mini keels when it come to hitting an object or ground. Where as if your using the boat on weekends, a bit of racing & short coastal cruises, dagger boards may offer better performance (fun factor) over keels. Knowing your not far away from help if you do hit something & damage the DB's. Overall design still plays the biggest roll I think. If you design a high performance cat you will have db's. At the same time you cant expect a huge boost in performance if you go slap some db's on a Lagoon.
It's worth saying why catamarans have a problem with upwind performance, which is mainly WINDAGE - there are two hulls, the rig and usually a bridgedeck (with standing headroom and good water clearance) above the water, all being pushed backwards by the wind, so it needs extra lift from the keel(s) to counter this and go forward. So catamarans are usually sailed a little more free to the wind, to reduce the head-on windage, get more drive from the rig and keels, and use the extra speed from the slim hulls to generate more apparent wind and give more push - so the VMG to windward goes up. Also, as the boatspeed increases off the wind, mini keels get into their working zone, and lose some of the disadvantage that they have. But the angles and windspeeds that you can sail effectively are reduced - you have fewer options - with mini keels.
Was out sailing with my friends FP Mahe 36 last week-end. This boat has mini keels and a traditional hull shape for a cat I believe. In ligth wind we tacked best at 32 deg at TWS 5m/s and was doing between 7 and 8 knots, with the WMG around 4,3 knots. Think that is amazing for such a boat. This means that daggerboards is not your savior for good upwind performance. This boat has a lot of cruising stuff onboard, but not excessively. Agree with you Nick, no daggerboards needed for a cruising cat, but keep the weight as low as possible and be sure that you actually can trim the sails correctly, this makes a huge difference in sailing speed and upwind tracking angel.
Our race winning 45 Ft Spronk Catamaran Skyjack was sparse by comparison to what you all are after but I would say a few things I felt were compatible with the long distance cruising. Specific to this video, our boat had centerboards. Pivoting boards have the distinct advantage of being able to break loose on impact of something in shallows or mid ocean at night when something unseen could be floating just below the water. The up and down lines are cleated in pressure releasable inline clamps. I do not know if this is feasible in the design considerations, but if you hit something at speed with a dagger board...it can be quite devastating. Perhaps you are already aware of this option or not. Pivot versus rigid box. I think you can get similar tracking upwind effect from pivoting boards. I am excited for this build! Thanks so much for being so nerdy about it.
a couple of suggestions when you’re talking to someone who is not in their native language: don’t use idioms and ask simple questions. E.g. you said ‘break the mould’ at one point in the middle of a long-winded question and we didn’t get an answer, I think because he didn’t understand your question. There were a few of these where the answer would have been really interesting but we never got it because he didn’t understand what you were asking
Quite right. I work in a mainly-French partly-Spanish technical team, and use of plain English is CRITICAL to be understood. It takes a lot of practise for native speakers!
A great question concerning performance with vs without daggerboards. The question here (and I think Antoine's answer) is really about the necessity for daggerboards in a circumnavigational boat, which is what Nick and Terysa are going to be doing. Monohulls circumnavigate the oceans at 4-8 knots; their 1370 will do that on a calm wind day with a good light wind sail. They will probably not be racing in Sydney Harbor, nor will most cruisers who buy cats to cruise on, and most of their circumnavigation will not be upwind. The 1190 is designed as a performance boat for coastal cruising, not circumnavigation, at least that's what Seawind has told me (though I'm sure it can sail oceans too). The 1160 and up do very well sailing oceans with mini keels, and there are additional negatives to daggerboards in the ocean (th-cam.com/video/bY-JM4GS5cw/w-d-xo.html). For the extra 1-2 knots, which is what Antoine explained here, is it necessary to have daggerboards which add complexity, take up hull space, and require extra skills to use properly; or, is it best to keep things simple? Nick has used the word "simple" many times. I happen to agree. Maybe they are looking for performance, but not racing performance. Maybe it's more about "feel."
Correct me if I am wrong, but I believe when we talk about hulls (in English) that have less curve between the bottom of the hull and the sides of the hull, we are talking a boat having a "Hard Chine" (vs. rounded chine or soft chine). At least that's the terminology I learned as a kid with a boat building father.
As somebody who is wanting to go cruising in a catamaran it seems to me a big advantage of daggerboards and possibly retractable rudder is a very small draft Also - should you hit ground with the daggerboards - that may be preferable to hitting with your keel. OTOH I understand that some catamarans with daggerboards cannot (or should not) be beached as the hull could be damaged. Also you cannot block up such a hull. Even though I do not intend to race - perhaps daggerboards is something to consider together with all the other parameters... Thank you for this interesting info.
Really interesting discussion. I take my hat off to Antoine for talking to a very technical subject in a language that he is not familiar with , particularly with a lot of techie jargon
There is a couple of other important factors like you get much less leeway with daggerboards, especially when doing over 8 or 9 knots. The ability to raise daggerboards in stormy conditions will allow the cat to slide sideways if hit by a rogue wave. They are also fun to experiment with when really getting the boat balanced. Cheers Rustie..
For a cruiser this sounds related to safety and important: "The ability to raise daggerboards in stormy conditions will allow the cat to slide sideways if hit by a rogue wave"
This is a great series. In the Sailing La Vagabonde episode Riley said he hoped to see people going to boat shows and instead of asking about the color of the pillows ask for the Bruce number. This series is going to completely rock every boat show from now on. (The news today about promising Covid vaccine trial results? My third thought was, "The Baltimore Boat show!" What's sooner?)
30 ,1370's ordered off the plan before the first one has hit the water.!!!! That shows you that Seawind have hit the nail on the head as far as length of the cat and easy sailing ability and style -both inside and outside looks. Well done Rubyrose as well. A great collaboration between sailors and a manufacturer. Really well done.
SY Ruby Rose, We studied this in school and i can not stress this enough; WEIGHT is everything when it comes to a catamaran design. (model testing in a wave pool with accelerometer measurements) You're correct about the wetted surface area and how that will provide more speed (less wet) and/or more angles (more wet/keels). There are also advantages between the depth that the vessel protrudes into the water with respect to laminar and turbulent flow vs the water pressure.(nerd talk but you hit the gist of it in the video) Running several tests with long, short, thin, wide, aero (hydro) and other variations, through testing we noted that the overall weight mattered the most. (keel design did reduce leeway and assisted overall tracking but not as much as we had hoped. Sad engineering students...) The center of effort and the center of drag seem to be more important in a cat vs a mono. In general it was very difficult to change those two locations on monohull for a given point of effort. But a cat seemed to be able to vary the center of drag force wildly with weight changes alone. (we did not have the funding to change hull shape throughout the test period.). Thanks for the video, it's interesting to listen to a discussion about how they have to build cats and all the design options to take into consideration. Kevin Water Wings Saling and Diving
Very nice technical discussion. Clearly summarizes pros and cos of daggers. Personal sailing style and appreciation of speed plays a role in the choice. I for one enjoy trimming for high speed and love the ability to gain even 0.1 knot and 0.1 degree of pointing ability and would not give up dagger boards. However, I agree with the conclusions: if you cruise the trade winds you do not need them. You will appreciate the extra space in the hulls, the easier sailing, the more affordable construction and simpler upkeep. On the other hand you may love them when they help you getting away on a tight lee shore, sailing the thorny path or getting that last anchorage in shallower water.
Adding to the discussion. In my experience, fine entries on either a Keel, Centre Board or Rudder makes steering the boat more critical and unforgiving where the finer the leading edge, the more easily they are to stall and create drag, slowing the boat down and dropping pointing off to Leeward. In balancing a boat, if you look at the water flowing behind the rudder, the flow of water should be linear. If the rudder shows a large amount of wash, the sails are over sheeted. This is critical where the boat has a balanced rudder having little feel of weather helm. Looking forward to the discussion of laminating the hull and the inclusion of Carbon Fibre in high stress areas in the 1370.I would like to know if the Hull is laid up in Vinylester, what's the point of using Carbon Fibre for high load areas? Was E-glass used over S-glass and why?
My 1979 30ft Iroquoise Mk2 has isometyric hulls (stubs) which I am VERY happy with, its probably a bit slower than the daggerboard version but I am a cruiser not a racer and I think it points VERY WELL. Weymouth then round Portland Bill to Dartmouth 9 hrs 15 mins (around 58 miles and wind from 10 oclock after getting round the bill.
16:09 I think what he’s trying to say here is the tracking ability of the boat is corresponding to the speed of the boat through the knuckle, keel and rudder, but also the dagger board. All of these things work better in high speed conditions. Because dagger boards work better in high speeds, you don’t need the much length to reach good results in high speeds.
Six months ago I spoke with a very successful, well-renowned multihull designer on the dagger board vs mini keel subject (he has designed both with extreme success). I have an F-9A tri w/ D-board and was leaning towards D-boards on a cruising cat because I didn't want to give up too much performance. He thinks for most people, for true cruising, mini-keels are the way to go. 1) D-boards are prone to damage and expensive to fix. Keels protect the rudder and drives. 2) D-board cats cost substantially more and the narrow hulls give less space and capacity. 3) The typical cruiser will overload anyway which negates much of the fast cat potential. But if you plan to race more and cruise occasionally, Maybe D-boards are a better choice. The conversation definitely makes me reconsider what I want and need. I'm still on the fence but now I'm about 70/30 in favor of keels. Since I will have to buy used due to my budget range, and there are very few options for D-board cats, the decision may be made for me by my bank account.
Many current designs have far too much windage, which really affects windward ability. A Woods Banshee will point higher than most monohulls upwind. I discussed design of the Gypsy with Richard Woods. He said the dagger board was more important that a rounded hull v a dory hull. This especially so in a confused sea, as mini keels are not deep enough to work in clean, un aerated water.
I am no Architect but I sailed both types daggerboard cat and keel cat (French cat KL 28 has both versions) All things equal a daggerboard cat is SAFER because in tough conditions it won't drift much upwind unlike the long mini keel cat. same result in very low wind. The draw back of daggerboard cat is nil except if you want to beach which you cannot do anywhere with a daggerboard cat. Last daggerboard cat are typically lighter and faster... they allow to avoid nasty depressions meaning they are safer. At max speed an Outremer will go 20-30 pct faster than a same size Fountaine Pajot... meaning much more than 2 knots!!!
Daggerboards are better to have for upwind sailing, but if most cruising is downwind then it matters less often. (Of course if you had daggerboards, you may go upwind more often.) Sometimes it is useful to be able to go more quickly to windward though. Sometimes a destination is to wind, or the wind is against your desired general direction. As with everything, it's a tradeoff of cost, space, performance. Daggerboards add performance, but take some space and add cost and complexity. Personally I would much prefer to have daggerboards in a performance boat. If I were to consider a Seawind 1370 I would inquire about (adding) them.
My first cat was a 16 ft Hobie cat. It was all over the map but still convinced us that we boys knew how to sail (falsely). Later on I upgraded to an 18 ft Hobie and it was night and day better---but we could hardly lift it.
For a cruiser mini keels are a much safer option. When you are trying to get into that really shallow bay or weave through some tight coral reef, hitting something lightly with your mini keels should result in very superficial damage, whilst your sail drives and rudder are protected behind. Try that with your dagger board yacht and you either snap off your dagger board (down and this damage can be really bad)), or hit directly with your sail-drives and rudder causing extreme damage. Seawind mini keels are sacrificial so even in a very bad situation, you may rip your mini keel off and still not have a hull breach. On top of that if you had to, you can beach your mini keeled cat on the sand with an outgoing tide for urgent maintenance, impossible on a dagger-board cat. And while a little performance may be lost, a well designed catamaran with mini keels can still point very well. We comfortably point to 30 degrees AWA with our Seawind 1260 leaving the autopilot in control holding the angle and speed. I know we are biased to Seawind as we live on ours, but they are great balance providing a true performance cruiser.
Why do you think you can't beach a daggerboard cat? You have to lift or swing your rudders, unless you have a protective fin in front precisely for that purpose, which also protects the props if they are built-in. I've been on a daggerboard boat and beached it for repairs, owner had swing-up outboards and the rudders lifted too, it was easy and simple.
@@ApprenticeGM Having outboards is the key to your point here. In my opinion a cruising boat has inboard diesels with big alternators that give each alternator a 100-200 amp charge for your house battery bank. An outboard can only typically charge at around 15 amp. Yes we have over a kilowatt of solar, but there are times when it's raining and overcast for a week at a time, so no solar charging possible. We have a 690aH lithium battery bank so with outboards that would take 46 hours to recharge and would most certainly fry your alternator if it could charge lithium at all!. Coupled to that we heat our hot water tank from the engine cooling system as well. If you want daggerboards, then the 1190 sport is the boat for you with outboards and daggerboards. If you want to go cruising then the 1260 or 1370 with inboard Yanmar's and mini keels has my preference.
@@SailingNoRegrets the boat i was on had a generator in case you had to charge batteries using fuel. 2kw solar. Outboards meant no drag when sailing. Much better setup than 2× inboard imho. Cheaper, simpler, lighter, less maintenance etc. He preferred to sail not motor everywhere so outboards suited his sailing preferences (& mine). But it proves u can Beach a daggerboard cat easily. Mini keels suck, cheap cop-out.
Yeah, thats a literal drop in VMG by like 50% I remember a light air race once in Geograph Bay, where a mini-keeled cat was doing what I assume was about 1 knot VMG while our similar sized and rigged cat was doing about 5 knots VMG, we triple lapped it in a race which they didn't even finishing. They ended up selling the boat after and buying a boat with daggerboards after the trip from Geograph bay to Perth (200 kms) took 4 days while the trip took us 12 hours.
15 degrees!?!?!?! Holy cow! Balance cats has some really nice DB boats, some where they don't protrude above deck. Some loss in storage in the hull lockers, but otherwise, a passenger would never know the difference. Great time to be alive, well, except that entire 2020 thing. :-(
@@Kruncher55 Some daggerboard trunks are essentially invisible (for example if integrated with the outer hull), though even if well integrated, they will take some space.
Another excellent discussion. I understand that some would label me as a heathen but I wonder if a centerboard incorporated into a shallow keel structures on each ama, similar to a Garcia, would offer similar performance as daggerboards but reduce the chance of severe damage with touching bottom. I was hoping that he was going to touch on that but I may have been the only one thinking this way. Looking forward to more of these. Cheers
LOL, I must be some OCD also. I know it's there, seen it in all the episodes, but I'm guessing that they have moved on. I believe that is his parents house where he was during the lock down / quarantine. ast time I had a position check (ways back), they were in southern France back at the boat. Episode 114 end of June / Beginning of July
I have a question?, what if you design a cat with mini keels (for protection of the sail drives) which has a retractable "daggerboard" which slides/folds inside the mini keel, would there be advantages to such a design and would it make a huge difference in the pointing ability of the boat?
I know it wouldn't work for a cruising cat but you have to have seen the shape of the Hobie 14/16 it was truly revolutionary for its time and really addressed the dagger board need and boy do they point!
Er - Hobie's were the worst pointers ever. I raced Hobie 16's and switched to Cobra 16' cats and then stingray 18' cats and we'd always laugh screaming past a Hobie at +25% speed and pointing 25 degrees higher lol. They were good off the wind in choppy seas - less likely to bury the nose - but going to wind wasn't their thing. The 18' Hobies introduced daggerboard precisely to counter that problem. The 17' Hobies (single handed racing) also had daggers.
I really enjoyed that discussion. Call me crazy, but it seems to me that if a catamaran was designed to have much smaller daggerboards closer to the bow-knuckle that it would increase its pointing ability working in conjunction with the rudders? I don't see this anywhere, so perhaps there a reason for it, it just seems as though it might be an interesting future design? They would also be located in an area of the hull which doesn't consume livable space. Thoughts? On a side note, The little lady looks so good as a result of having those extra weights on board. The price we pay for love.
With respect to your designer--hull forefoot and topside angle has bugger all to do with leeway prevention. Of course the leeward bow is going to be in the water and John Shuttleworth (a damn fine designer who really knows his stuff) designs all have a knuckle coming out of the side of the boat--like Pescotts, and both these boats go to windward like a train. Shuttleworth also has very good evidence that you only need one daggerboard--loss of performance is aorund 1-2% Re daggerboards why then does Seawind make the 11.90 with daggerboards and market this as their performance boat?? A Pescott catamaran against 1160's (same length) wins by over an hour in round the bouys races in Sydney harbour. 5-15 degrees to windward is significant! Weight is mighty important to performance, however even a light boat with mini keels is not going to go well to windward. You're splitting hairs, if you want a great sailing boat especially to windward go for daggerboards. If you're not worrying about performance let alone windward ability go for mini keels.
I'm not sure they explianed those points very well at all, and am not sure too many people are aware of the benifits of single dagger board design. A deep dive might have also included center boards (especially considering RR is a Southerly with a retractable center board). The advantages of dagger boards regarding manuverability was also lightly touched on.....feels a little like he was trying to justify the mini keels....I personally would have preferred a more frank and complete discussion on the compromises and ultimately how the Seawind 1370 meets their criteria. But in the end not about me, think I'm reacting to the click bait
Yes, and I worry that Nick is going further and further down a hole with this naval architect. “We want a cat that can sail as well as a monohull” just betrays sloppy thinking and fairly dense reasoning and makes it seems he is just trying to justify his choices. You simply cannot have a truck that drives like a Porsche- they are fundamentally different. It would be so much better if instead of Nick trying to dummy stuff down and justify himself, as well as lead and prod the naval architect, that he gets someone with serious history in yacht design on. Shuttleworth, Woods, Kelsall, some of the many NZ. Nivelt in France has more boats under his belt than dinners (maybe :).
Agree, even a couple of degrees higher pointing can make a lot of difference at the end of an upwind leg, assuming you're not losing VMG by pinching. But cruisers pick their passages and timings to avoid upwind if possible, so it's less important. More significant for me is that mini keels don't work at slow speeds, so you end up motoring when you could be sailing :(
@@bluemu if you can convince Sailing Millenial Falcon to get onto this topic I think we'd be in for a treat. Adam is an aero engineer, and like all us good engineers, he seems to be unable to help drawing diagrams and geeking out over resultant forces and bending moments. I think most viewers probably come for "sailing channels" and want to learn a little, versus people who want a deep dive and are happy when a boat design question somehow turns into five hours reading through boatdesign dot net forum (or is that just me?)
Seawind model 1190 is available with boards or keels depending on what your primary use is going to be, you should try and get to sail on both to compare, I reckon Seawind would be keen to make it happen. I'm a racing sailor so would want boards except for going aground or hauling out. Choices!?
I think the pointing/performance is by far the best part of dagger-boards. After all, your sail-drives and rudders will be almost as deep as the mini keels so getting rid of the keels doesn't buy you much draft reduction.
Hi really enjoying your journey and adventures in your 2nd interview on daggerboards one aspect was not covered and that is the comparison of the tacking ability of the two. Can you address this in your next interview as it is one more piece of the puzzle towards a decision which is best for me but at the moment leaning towards daggerboards.
Love Technical Tuesday!! Thanks for another overload of information Nick!! I always questioned to have either daggerboards or mini-keels on the cat I plan on getting in the near future. Fair winds and following seas Ruby Rose !
That guy is a catamaran hull designer? I have shoes that are older than him. I am not saying he's incapable or that his young age is bad, is just that I'd think he would be a 2nd in command or something. I'd like to know what program he uses for cfd, computational fluid dynamics. I'd really love to see a couple of his and other designs and see the pros and cons of different design elements and how they affect the whole b&oat. Plus how the weight balance of gear can affect performance. CFD is a powerful and enormous time savings tool and we as consumers are getting huge benefits from it.
Thank you both. Looking at the polars it really does look like max VMG is no where near the highest you can point. It would be great to see a discussion of downwind strategies and downwind-polars with a symmetrical kite, goose wing jib+ code 0, vs gybing downwind with a code-0 only. Not just speed and VMG, but also comfort and other factors how a catamaran is designed to go downwind best.
Thanks Nick! Quick question: He stated that dagger boards increase your upwind performance by 5-15% or was that 5-15 degrees? And it that the total improvement? (ie. 5 degrees closer to the wind on each tack for a total of 10 degrees improvement?) We have just chartered a Seawind 1260 out of Key West and had to sail to windward both to and from the Dry Tortugas (Murphy's Law!). When trying to sail to windward 5 degrees on each tack is a _huge_ improvement. The boat would sail at 39 degrees off the wind but we were slipping to leeward by another 6-7 degrees. To be fair the was current in the area and it was hard to judge the magnitude of the effect from the current. We had to motor-sail to get home and I felt that 5 or 6 degrees better windward performance would have made a huge difference. Are there any numbers comparing the windward performance of the 1370 to the 1600? I know they are different boats but it would be nice to see the trade-offs in a real world example. GREAT job! ~Peter
So I'm gonna paraphrase and some one can tell me how I'm wrong. According to Antone' the faster you go, the less daggerboard you want in the water. Since the daggerboard gives you a 5% - 15% ability to point higher, that would mean one of the following is true. As you pull up the DB during higher speeds, you lose the ability to point as high, and you need to fall off the wind. Or, what I think is more likely, as you gain speed you can point higher w/o a daggerboard, gaining back that missing 5%-15%. thoughts?
a wing generates more lift the faster you go (up to a point), a daggerboard is just like a wing - it generates sideways 'lift' so the faster you go, the less wing you need in the water. But having anything in the water also has drag, so lifting it up reduces drag, so your speed can be better, which means more effect from the daggerboard. So you can see why it makes sense they're adjustable to adjust the amount of effect you need from the daggerboard to match the speed.
@@quickdry3 Plus he made it sound like you don't need as much daggerboard at high speeds / high pointing if your bows stay wet; you'll still track ok and can cut daggerboard drag by lifting.
@@afterexposure right, (I'm not a naval engineer/architect), but ignoring any effects from hull shape, when the bow is out of water the length at waterline has decreased, and it's also moved the sail's centre off effort forward relative to the boat length at the waterline
Love the series, love all the Tech Tuesdays... but (@ 08:26) CJ (my lady) looked up and exclaimed, "I want to hear more about the talking daggerboards!" LOL As we said love everything you guys do! Sorry to say we are dyed in the wool old school monohull sailors, and are not ourselves interested in Cats, but we just may keep watching when ya'll disembark from RRI for RRII. Good luck!
Thankyou for the video. It was very interesting and reminded me of the Delos video they did with Amel's designer. There is a lot to know and we''ll probably never know it all. From the Delos video the designer got into sails which I found more interesting as they are something the average sailor can influence unlike hull design. Whether you're sailing a cat or mono they all seem to squat at speed and this I learned was due to lift created by the headsail. It makes for a more comfortable and drier sail as I guess both boats use that lift to plane more on the beamier part of the hull which kind of ruins the theory of hull profile preventing drift to an extent. Your designer was struggling with English but that's fine because no one has heard my French. Please thank him for his time.
Firstly, congrats on a great channel, always look fwd to new content. A couple of thoughts on daggerboards: the argument for daggerboards on a cat is the same as for having a deep high aspect fin and bulb on a cruising monohull. Both would improve windward performance, but other compromises make more sense on a cruising boat. It's possibly arguable that leeway on a cat when the force component of a boat going hard to windward is lateral, adds a safety margin. A cats lower inertia could make it more tiring beating into a chop, too.
Most methodical approach to a boat purchase I've seen. All documented on TH-cam episodes. A year or so when we're all on that Seawind sailing, it will be worth it.
Thank you so much for this. As a non sailor much was over my head, yet it was made so understandable. Antoines grasp of technical English is amazing and the whole subject absolutely fascinating
I was a Hobie Cat sailor back in the 70s, you ever look at the hulls? no dagger-board, no keels and they haul ass... wonder why no one has made a bigger cat.... used to ride the surf with the Hobie right into the beach, the rudders would kick up..
I would love to hear more comments about the deep vee hull shapes (lateral resistance) and double ended cats (seagoing ability) of the Wharram designs. Looking forward to watching you build with much interest. Thank you for sharing.
Deep V has many disadvantages. They hobby horse, which kills the airflow over the sails. The centre of lateral resistance, on the hull, is far forward and changes with speed.
I enjoyed this, information was quick and understandable. Basics are clear here, I would like to see the hull shape with a mini keel, is it more blended or more flat to the side load of the keel.?
Certainly GunBoat and other performance cruising Catamarans shed weight by using carbon fiber everywhere and they are very expensive. As Antone stated a Daggerboard cat that is light will point 5 to 15 degrees higher than a similar hull with a mini keel. We know the giant huge wetted surface cruising cats could not use daggerboards, it would be like putting lipstick on a pig. The same can be said for putting minikeels on a carbon fiber low wetted surface catamaran hull. If you want to sail downwind in a whale go with minikeels. If you like pointing higher and going upwind at times then get a catamaran with light hulls and daggerboards. It is as simple as that.
@Sailing Ruby Rose sorry Nick but @Serhii Almazov and @Gerrit Govaerts are correct. Glad someone caught this. Made my engineer's brain twerk when I heard it. Back to school with you! Hope you are learning as much as we are from all this. Thanks for this series and really look forward to seeing the boat in Annapolis or Miami one day.
Sorry, Didn't find that this video increased my understanding of Catamaran designs and daggerboards. I do understand that it is more complicated than I had assumed, but I was hoping to better understand draft and grounding considerations and how wind speed affects the tradeoffs. I guess I was looking for the easy way out.
Great stuff!!! Maybe this is address farther down in the comments but it was mentioned that daggerboards help rudder reactivity. Does this relieve pressure on the rutter? If so, that seems very beneficial not only to upwind performance but decreased stress on the rutters' mechanical components? Am I wrong?
What are the expected consequences to the integrity of the boat when hiting a rock, reef or floating container whith both systems? (Minikeels / daggerboards)
Hello. We have a Gemini 105 M. We are converting it to the power (mast removed). We’re trying to figure out if we still need the centerboards. We already removed the rudders. Installed 2 yamaha f70 motors. Purpose-crossing from the Miami to Bahamas. We cant figure it out. Manual says that it is not recommended to use them while motoring due to the drag. Is there any purpose in them for our use in it? Those are 300lb each. So looks like unnecessary weight. Thank you.
the chord length of most catamaran dagger boards are not long enough for their speed upwind, longer chord length would give better upwind pointing ability
Not true! A deeper board with LESS chord will always have more lift. Longer chord means that it takes more boatspeed to get smooth flow from the front to the back of the board, and you need the smooth flow to start creating lift. So longer chord needs more speed, but at this speed a deep, narrow daggerboard is creating massive lift, so you can lift it up and reduce drag, and still have enough lift!
@@sailingstar8182 My statement is true, read what I wrote again. You are discussing something I haven't mentioned, chord length is to be matched against the boats designed performance, would your design scenario make a lagoon perform as you suggest? Longer chord length gives better pointing at slow speed, shorter chord length at high speed.
How to integrate a swath, swath2cat, or norstein x-bow, or even retractable foils assuming it can be safe, hull design Into a 55ft catamaran - to help manage sea state?
Is that guy a high level designer ? I had cat with mini keel, sold it after 4 months for one with a daggerboard. No pro will sail without dagger board. I would preferred him saying 60% hitech and 40% art.
"SPEED TO LIFT RATIO. As the speed doubles, so the lift quadruples. A coefficient of 2". He says "quadruples", perhaps he means speed in power 2 and not speed multiply by 2. speed**2 and not just 2*speed
Thanks for a great informative video. Don't you think that pointing ability is only really needed when you racing. Cruising around the world, pointing doesn't really become an issue? Time should not really be an issue either. Enjoy all your videos.
What is "hull shape?" Prismatic coefficient? Hull beam? Hull draft? Wetted surface? The designer is puzzled because the term is not used by naval architects.
Nice info.. I love mini keels if the protect the prop and rudder . But cats with dagger boards are very nice to have. The dagger boards you don’t need to use them al the time. It’s nice going sharp to the wind. Or if the sea states is not stabilising your boat. So having daggers ., it can be a very nice tool . Obviously you need some de discipline to check of there up in shallow water.
great video , but I would loved to have also included in it the centerboards . It seems that centerboards is in between daggerboards and mini keels why aren't they almost used in catamarans?
@@gerritgovaerts8443 lol I'm trying to imagine a floating apartment like a Lagoon flying a hull and using C-foils... I suspect they're all purposefully kept out of the equation since a cat can't heel and 'wash' off wind force the way a cruising mono can, tools to really load them up would suit racing, but even performance cruisers in general seem more cruisers with better performance, not performance with a little cruising - like the "Fancy SUV in the suburbs", the closest to mud it sees is a dirty puddle, but at a push it could drive on the beach - performance cruisers cats can go faster, but not designed for the loads of racing.
Pointing starts with an immersed bow? So why dont they put the daggerboard nearer the bow where it doesnt have to be that deep while retaining the mini keel near the center, or is this a stupid question ?
Our Seawind 1160 sails at 32° apparent. The 1190 Em with daggerboards does the same. The only difference is leeway. The difference measured at Hamilton Island Race Week is 2° only
...at what windspeed and boatspeed do you get similar pointing? That's critical, because mini keels don't work at slow speeds. And sure you can point, but what's the boatspeed at 32 degrees apparent? Because the forward drive comes from the keel lift (not the sails - they just push the keels sideways, or slantwise, which then pushes the boat forwards). Daggerboards will always have more lift potential, which always means more boatspeed. Sure you can point at 32 degrees with mini keels, but you'll be going slowly, and sideways, unless there's plenty of wind to start getting lift from the LAR keels. Don't kid youselves - sail both types and find out for yourselves!
Now we are getting into the pointy end of sailing. No pun intended... I do like intelligent discussion about yacht design. This will be an amazing series. The sailing Adventures are great, but with a crap design, it will never be amazing... You will have to install hydro brakes on the rudders to slow the cat for fishing. I don't know what the success rate of catching fish, using a lure will be at 20 knots...
Hydro brakes? Reduce sail is easier!
Sea anchor? They make really nice grab bag/sea anchor units that obviously work s both.
For anyone interested in what the actual difference would be, because the video just says stuff like "only 5-15 degrees less height upwind and some increased drag" means, 2 boats, identical in every way, using the numbers quoted, say 15 degrees less height upwind in medium air with mild chop. Without taking into account other inefficiencies from mini keels in way of ventilation etc (and other real world things).
A boat with decent daggerboards setup right will do, say 10 knots boat speed in 15 knots of breeze at 50 degrees, thats a true VMG of 6.43 knots. (Velocity made good upwind).
As opposed to literally an identical boat with mini keels does 8.5 knots (due to added drag and reduced lift) at 65 degrees (because it isnt pointing as high and is making leeway due to reduced lift also dropping apparent wind) in the same 15 knots of breeze, means it's doing 3.59 VMG.
Thats literally half the speed to your destination upwind.
If your destination was exactly upwind 50 nautical miles it would take 7 hours 46 minutes with the daggerboard boat and with mini keels that would take almost 14 hours.
Very good example! I would say daggerboards are ESSENTIAL on a performance or performance cruising cat. You don't even need 2 x daggerboards, you can have a single larger one, which reduces build cost complexity, maintenance and reduction in interior livable volume.
Thanks for a practical example. I've always heard that most crusing is downwind, but maybe that's from monohull sailors. How often do you end up cruising upwind? (Of course if you had daggerboards, you might go upwind more often.)
Loanword Eggcorn Exactly... I think most cruising is downwind because it’s more comfortable and much easier, and in turn the cheapest location to purchase a used sailboat is at downwind locations, ie. southern Carribbean.
Simply here to learn some aerodynamics. This numerical example makes it easy to understand. So, the difference is roughly [cos(theta) / cos(theta + delta_theta)]^2 . Quite big indeed.
I felt so sorry for Antone' to see his frustration of trying to get his vast knowledge thru the language barrier!☺
We know from experience that it's one thing to be able to speak fluently in a second language, but it's another thing entirely to be able to translate jargon from a niche field of expertise from one language to another. He did an amazing job!
@@sailingrubyrose You were a good interpreter; you must have a fair understanding of the French language.
Respect to Antone for keeping on going - in the end his English is still much better than my French (I know maybe 3 words).
@@sailingrubyrose Formidable. I noticed on another TH-cam video that a heavy accent (Antone's is not bad at all) and a bad microphone made it impossible. But a heavy accent and a good microphone - no problem.
Regardless, I wish you permitted Antone more time to explain what he was telling us , since ruby rose interrupted too often with personal assumptions. ..imo
Great to hear a naval architect's viewpoint. There's one key thing he said that you didn't emphasise - daggerboards start working at much slower boat speeds, because they're high aspect ratio, like glider wings. You can't get this slow-speed lift from hull shape, or mini keels, as they're all low aspect ratio lift devices, and they only start working at higher speeds through the water. If you want to sail almost all the time, including upwind in light airs, you need daggerboards. If you want to be sure of getting home, without relying on the engine, you need daggerboards. If you're on a lee shore, and need to point your way out of trouble, you need daggerboards. And they make the sailing more fun, if you can stand the extra space and complexity!
Sponsors wink wink
It's the other way around. Dagger boards don't work at low speeds and start to work when they reach their optimum speed capability according to their design - chord measurement etc.
a achitect who is stil wet behind the ears. who just working for a expensive party. could i ever take it seriously.
@@robertcain3426 I disagree. From personal experience I can tell you that daggerboards at low speeds can make a radical difference in pointing ability vs mini keels.
My experience in racing my cruising cat with one large daggerboard against cats with keels showed that daggerboards are far superior not just for pointing but for vmg also. My boat will point with Farr 40 and sail a bit faster, sail 5 degrees lower and I blow them away. There is no need for two boards, the boat doesn't heel or know which tack it is on, assuming the board is vertical. One other point, if you run aground with both mini keeps good luck getting off. Go to any cruising anchorage and see how cautious the keeled cats are about depth, more than the monos.
One thing he kept saying, but Nick goes right past because he's hung on pointing, is that you get so much more flexibility on other points of sail with being able to REDUCE the amount of drag in the water (raise the boards) when lateral drift is less of a factor. So with dagger boards, you get the best of all worlds as it pertains to performance, higher pointing into the wind, and faster going away = better VMG at all points of sail.
Ok , here's my two bobs worth
On my 45ft cat l have 250mm mini keels mainly to protect the rudders when l beach her
BUT l also have a swing centre board & l can say it does make a MASSIVE difference in pointing when it's down....best of both worlds...cheers
Yes , l have most of the photo's of when l built her
Would love to know more about your cat. Self designed?
Sounds like the result of the conversation was that it’s better to have daggerboards! It would be nice if the 1370 had a daggerboard option for those who think pointing higher and having a shallow draft are important.
Yes
The problem is striking a balance between performance and livability. If there's one thing I've learned from being around boats and watching all of these sailing video's is that there's always SOMETHING to do/fix and the less crap you have to deal with, the more time you actually have for... you know... living ;). Considering most cruising cats are about the destination vs. the journey, it seems to me the tradeoff is worthwhile. Especially given that the 1370 is a performance oriented cat to begin with. From a practical perspective, the 1370 will already do circles around many other production cats.
Anyway, always interested in opinions from those who know much more about this than me as I'm still learning.
@@brois841 Some boats put the daggerboard trunks up against the outer hull, and the intrusion into (and reduction of) living space is almost not noticeable. For a true performance boat, daggerboards would be beneficial.
5º to 15º is a lot! 2 to 3 knots down wind is a lot! I need daggerboards in my catamaran! In the inter tropics zone where the wind is soft this is very important, is the difference between use or not use diesel.
I have owned a Lagoon 380 with minikeels and a 38' cat with daggerboards. The 380 was a good sailer by Lagoon standards bit still made a lot of leeway close hauled. The mini-keels stall at a much higher speed than a daggerboard and at that point you can feel the boat slipping sideways and the increased the drag of the keels slows you down. You have to be very aware of this effect and try to keel the keels efficient for a long as possible even if it means bearing away a little. It was still fun to sail the Lagoon but virtually impossible to prevent significant leeway. We could do about 7.5 knots tacking through effectivly 120-130 degrees with leeway. Most modern cruising monohulls of similar length would easily outsail us to windward. The daggerboard cat was completely different. In effect it is almost impossble to stall the keels and the leeway was imperceptible. She was also much lighter than the Lagoon so at 10 knots boat speed and tacking through 100 degrees, very few cruising monohulls could catch us. Downwind you can partially or completely retract the daggerboards which reduces drag and increases speed. It is a similar concept to folding vs fixed props. So in summary the daggerboard cat performed better in all points of sail and was a lot of fun to play with. Granted that some of that performance advantage was down to weight too. But both types of boats had their strengths and weaknesses, and as ever, it all depends on what you enjoy about sailing. My ideal cat has Lagoon type comfort with centreboards. John Shuttleworth has done some excellent technical papers on centreboards.
Nice vid on theoretics guys! Remember tho the beauty of daggers is that you can RETRACT. We only use our dagger boards when hard on the wind, which is maybe 5% of our sailing and the rest of the time we have clean and fast hulls, without dragging around mini keels...
Life on Jupiter is that on a monohull or cat?
Having sailed a 53 foot cat for 13 years it's pretty clear that dagger boards, hull shape, bridge deck clearance, sail plan and rig tension ALL play a significant role in sailing performance. The best way to demonstrate this to yourself is to get out on a dagger board cat in flat water (wave action confuses the result) set sail hard to windward dagger board up, push the windward board down, note the wake. Push the leeward board down note the wake. Next check the course made good to windward. Go sailing beach cats with and without dagger boards. It becomes patently obvious that dagger boards wind hands down in sailing ability, BUT that's not all. In shallow anchorages having dagger boards and retractable rudders is a MASSIVE bonus. Hiding from foul weather etc. My boat was built in the 80s, was in commercial survey and would out sail production FRP mini keel cats 20 years younger. So why am I telling you this ? Sailing to windward is going to happen, when you least want to but necessity will mandate that you do. A boat that sails well, into the wind, off the wind, is safer and will get you out of trouble when she needs to. A friend of mine has a Bob Oram 60ft cat that he bought with a single dagger board and retracting rudders, he sailed a lot on my boat and eventually installed a second dagger board on his Oram 60. MUCH more controllable for such a fast light displacement boat.
I think an important factor also is how you primarily are going to use the boat. When living on board I think there is a peace of mind about mini keels when it come to hitting an object or ground. Where as if your using the boat on weekends, a bit of racing & short coastal cruises, dagger boards may offer better performance (fun factor) over keels. Knowing your not far away from help if you do hit something & damage the DB's. Overall design still plays the biggest roll I think. If you design a high performance cat you will have db's. At the same time you cant expect a huge boost in performance if you go slap some db's on a Lagoon.
It's worth saying why catamarans have a problem with upwind performance, which is mainly WINDAGE - there are two hulls, the rig and usually a bridgedeck (with standing headroom and good water clearance) above the water, all being pushed backwards by the wind, so it needs extra lift from the keel(s) to counter this and go forward. So catamarans are usually sailed a little more free to the wind, to reduce the head-on windage, get more drive from the rig and keels, and use the extra speed from the slim hulls to generate more apparent wind and give more push - so the VMG to windward goes up. Also, as the boatspeed increases off the wind, mini keels get into their working zone, and lose some of the disadvantage that they have. But the angles and windspeeds that you can sail effectively are reduced - you have fewer options - with mini keels.
Was out sailing with my friends FP Mahe 36 last week-end. This boat has mini keels and a traditional hull shape for a cat I believe. In ligth wind we tacked best at 32 deg at TWS 5m/s and was doing between 7 and 8 knots, with the WMG around 4,3 knots. Think that is amazing for such a boat. This means that daggerboards is not your savior for good upwind performance. This boat has a lot of cruising stuff onboard, but not excessively.
Agree with you Nick, no daggerboards needed for a cruising cat, but keep the weight as low as possible and be sure that you actually can trim the sails correctly, this makes a huge difference in sailing speed and upwind tracking angel.
Our race winning 45 Ft Spronk Catamaran Skyjack was sparse by comparison to what you all are after but I would say a few things I felt were compatible with the long distance cruising. Specific to this video, our boat had centerboards. Pivoting boards have the distinct advantage of being able to break loose on impact of something in shallows or mid ocean at night when something unseen could be floating just below the water. The up and down lines are cleated in pressure releasable inline clamps. I do not know if this is feasible in the design considerations, but if you hit something at speed with a dagger board...it can be quite devastating. Perhaps you are already aware of this option or not. Pivot versus rigid box. I think you can get similar tracking upwind effect from pivoting boards. I am excited for this build! Thanks so much for being so nerdy about it.
a couple of suggestions when you’re talking to someone who is not in their native language: don’t use idioms and ask simple questions. E.g. you said ‘break the mould’ at one point in the middle of a long-winded question and we didn’t get an answer, I think because he didn’t understand your question. There were a few of these where the answer would have been really interesting but we never got it because he didn’t understand what you were asking
Quite right. I work in a mainly-French partly-Spanish technical team, and use of plain English is CRITICAL to be understood. It takes a lot of practise for native speakers!
A great question concerning performance with vs without daggerboards. The question here (and I think Antoine's answer) is really about the necessity for daggerboards in a circumnavigational boat, which is what Nick and Terysa are going to be doing. Monohulls circumnavigate the oceans at 4-8 knots; their 1370 will do that on a calm wind day with a good light wind sail. They will probably not be racing in Sydney Harbor, nor will most cruisers who buy cats to cruise on, and most of their circumnavigation will not be upwind. The 1190 is designed as a performance boat for coastal cruising, not circumnavigation, at least that's what Seawind has told me (though I'm sure it can sail oceans too). The 1160 and up do very well sailing oceans with mini keels, and there are additional negatives to daggerboards in the ocean (th-cam.com/video/bY-JM4GS5cw/w-d-xo.html). For the extra 1-2 knots, which is what Antoine explained here, is it necessary to have daggerboards which add complexity, take up hull space, and require extra skills to use properly; or, is it best to keep things simple? Nick has used the word "simple" many times. I happen to agree. Maybe they are looking for performance, but not racing performance. Maybe it's more about "feel."
Correct me if I am wrong, but I believe when we talk about hulls (in English) that have less curve between the bottom of the hull and the sides of the hull, we are talking a boat having a "Hard Chine" (vs. rounded chine or soft chine). At least that's the terminology I learned as a kid with a boat building father.
As somebody who is wanting to go cruising in a catamaran it seems to me a big advantage of daggerboards and possibly retractable rudder is a very small draft
Also - should you hit ground with the daggerboards - that may be preferable to hitting with your keel.
OTOH I understand that some catamarans with daggerboards cannot (or should not) be beached as the hull could be damaged. Also you cannot block up such a hull.
Even though I do not intend to race - perhaps daggerboards is something to consider together with all the other parameters...
Thank you for this interesting info.
Thank you, for actually spending the time to allow any layman (me) to understand, and asking the questions I wish I could. Go well.
Really interesting discussion. I take my hat off to Antoine for talking to a very technical subject in a language that he is not familiar with , particularly with a lot of techie jargon
There is a couple of other important factors like you get much less leeway with daggerboards, especially when doing over 8 or 9 knots. The ability to raise daggerboards in stormy conditions will allow the cat to slide sideways if hit by a rogue wave. They are also fun to experiment with when really getting the boat balanced. Cheers Rustie..
For a cruiser this sounds related to safety and important: "The ability to raise daggerboards in stormy conditions will allow the cat to slide sideways if hit by a rogue wave"
This is a great series. In the Sailing La Vagabonde episode Riley said he hoped to see people going to boat shows and instead of asking about the color of the pillows ask for the Bruce number. This series is going to completely rock every boat show from now on. (The news today about promising Covid vaccine trial results? My third thought was, "The Baltimore Boat show!" What's sooner?)
30 ,1370's ordered off the plan before the first one has hit the water.!!!! That shows you that Seawind have hit the nail on the head as far as length of the cat and easy sailing ability and style -both inside and outside looks. Well done Rubyrose as well. A great collaboration between sailors and a manufacturer. Really well done.
SY Ruby Rose,
We studied this in school and i can not stress this enough; WEIGHT is everything when it comes to a catamaran design. (model testing in a wave pool with accelerometer measurements) You're correct about the wetted surface area and how that will provide more speed (less wet) and/or more angles (more wet/keels). There are also advantages between the depth that the vessel protrudes into the water with respect to laminar and turbulent flow vs the water pressure.(nerd talk but you hit the gist of it in the video) Running several tests with long, short, thin, wide, aero (hydro) and other variations, through testing we noted that the overall weight mattered the most. (keel design did reduce leeway and assisted overall tracking but not as much as we had hoped. Sad engineering students...)
The center of effort and the center of drag seem to be more important in a cat vs a mono. In general it was very difficult to change those two locations on monohull for a given point of effort. But a cat seemed to be able to vary the center of drag force wildly with weight changes alone. (we did not have the funding to change hull shape throughout the test period.).
Thanks for the video, it's interesting to listen to a discussion about how they have to build cats and all the design options to take into consideration.
Kevin
Water Wings Saling and Diving
Very nice technical discussion.
Clearly summarizes pros and cos of daggers.
Personal sailing style and appreciation of speed plays a role in the choice. I for one enjoy trimming for high speed and love the ability to gain even 0.1 knot and 0.1 degree of pointing ability and would not give up dagger boards. However, I agree with the conclusions: if you cruise the trade winds you do not need them. You will appreciate the extra space in the hulls, the easier sailing, the more affordable construction and simpler upkeep.
On the other hand you may love them when they help you getting away on a tight lee shore, sailing the thorny path or getting that last anchorage in shallower water.
Adding to the discussion. In my experience, fine entries on either a Keel, Centre Board or Rudder makes steering the boat more critical and unforgiving where the finer the leading edge, the more easily they are to stall and create drag, slowing the boat down and dropping pointing off to Leeward. In balancing a boat, if you look at the water flowing behind the rudder, the flow of water should be linear. If the rudder shows a large amount of wash, the sails are over sheeted. This is critical where the boat has a balanced rudder having little feel of weather helm. Looking forward to the discussion of laminating the hull and the inclusion of Carbon Fibre in high stress areas in the 1370.I would like to know if the Hull is laid up in Vinylester, what's the point of using Carbon Fibre for high load areas? Was E-glass used over S-glass and why?
My 1979 30ft Iroquoise Mk2 has isometyric hulls (stubs) which I am VERY happy with, its probably a bit slower than the daggerboard version but I am a cruiser not a racer and I think it points VERY WELL. Weymouth then round Portland Bill to Dartmouth 9 hrs 15 mins (around 58 miles and wind from 10 oclock after getting round the bill.
16:09 I think what he’s trying to say here is the tracking ability of the boat is corresponding to the speed of the boat through the knuckle, keel and rudder, but also the dagger board. All of these things work better in high speed conditions.
Because dagger boards work better in high speeds, you don’t need the much length to reach good results in high speeds.
Six months ago I spoke with a very successful, well-renowned multihull designer on the dagger board vs mini keel subject (he has designed both with extreme success). I have an F-9A tri w/ D-board and was leaning towards D-boards on a cruising cat because I didn't want to give up too much performance. He thinks for most people, for true cruising, mini-keels are the way to go.
1) D-boards are prone to damage and expensive to fix. Keels protect the rudder and drives.
2) D-board cats cost substantially more and the narrow hulls give less space and capacity.
3) The typical cruiser will overload anyway which negates much of the fast cat potential.
But if you plan to race more and cruise occasionally, Maybe D-boards are a better choice. The conversation definitely makes me reconsider what I want and need. I'm still on the fence but now I'm about 70/30 in favor of keels. Since I will have to buy used due to my budget range, and there are very few options for D-board cats, the decision may be made for me by my bank account.
Many current designs have far too much windage, which really affects windward ability.
A Woods Banshee will point higher than most monohulls upwind.
I discussed design of the Gypsy with Richard Woods. He said the dagger board was more important that a rounded hull v a dory hull. This especially so in a confused sea, as mini keels are not deep enough to work in clean, un aerated water.
I am no Architect but I sailed both types daggerboard cat and keel cat (French cat KL 28 has both versions)
All things equal a daggerboard cat is SAFER because in tough conditions it won't drift much upwind unlike the long mini keel cat.
same result in very low wind.
The draw back of daggerboard cat is nil except if you want to beach which you cannot do anywhere with a daggerboard cat.
Last daggerboard cat are typically lighter and faster... they allow to avoid nasty depressions meaning they are safer.
At max speed an Outremer will go 20-30 pct faster than a same size Fountaine Pajot... meaning much more than 2 knots!!!
I beach my daggerboard catamaran almost everyday. No problem at all
Actually I think daggerboard cat is usually slightly heavier that keeled equivalent.
I really can't wait for the first episode of 2022! (Guess it will be ready by then :).
Should be Mid 2021
Daggerboards are better to have for upwind sailing, but if most cruising is downwind then it matters less often. (Of course if you had daggerboards, you may go upwind more often.)
Sometimes it is useful to be able to go more quickly to windward though. Sometimes a destination is to wind, or the wind is against your desired general direction.
As with everything, it's a tradeoff of cost, space, performance. Daggerboards add performance, but take some space and add cost and complexity.
Personally I would much prefer to have daggerboards in a performance boat. If I were to consider a Seawind 1370 I would inquire about (adding) them.
My first cat was a 16 ft Hobie cat. It was all over the map but still convinced us that we boys knew how to sail (falsely). Later on I upgraded to an 18 ft Hobie and it was night and day better---but we could hardly lift it.
For a cruiser mini keels are a much safer option.
When you are trying to get into that really shallow bay or weave through some tight coral reef, hitting something lightly with your mini keels should result in very superficial damage, whilst your sail drives and rudder are protected behind. Try that with your dagger board yacht and you either snap off your dagger board (down and this damage can be really bad)), or hit directly with your sail-drives and rudder causing extreme damage. Seawind mini keels are sacrificial so even in a very bad situation, you may rip your mini keel off and still not have a hull breach. On top of that if you had to, you can beach your mini keeled cat on the sand with an outgoing tide for urgent maintenance, impossible on a dagger-board cat.
And while a little performance may be lost, a well designed catamaran with mini keels can still point very well.
We comfortably point to 30 degrees AWA with our Seawind 1260 leaving the autopilot in control holding the angle and speed.
I know we are biased to Seawind as we live on ours, but they are great balance providing a true performance cruiser.
Why do you think you can't beach a daggerboard cat? You have to lift or swing your rudders, unless you have a protective fin in front precisely for that purpose, which also protects the props if they are built-in. I've been on a daggerboard boat and beached it for repairs, owner had swing-up outboards and the rudders lifted too, it was easy and simple.
@@ApprenticeGM Having outboards is the key to your point here. In my opinion a cruising boat has inboard diesels with big alternators that give each alternator a 100-200 amp charge for your house battery bank. An outboard can only typically charge at around 15 amp. Yes we have over a kilowatt of solar, but there are times when it's raining and overcast for a week at a time, so no solar charging possible. We have a 690aH lithium battery bank so with outboards that would take 46 hours to recharge and would most certainly fry your alternator if it could charge lithium at all!. Coupled to that we heat our hot water tank from the engine cooling system as well. If you want daggerboards, then the 1190 sport is the boat for you with outboards and daggerboards. If you want to go cruising then the 1260 or 1370 with inboard Yanmar's and mini keels has my preference.
@@SailingNoRegrets the boat i was on had a generator in case you had to charge batteries using fuel. 2kw solar. Outboards meant no drag when sailing. Much better setup than 2× inboard imho. Cheaper, simpler, lighter, less maintenance etc. He preferred to sail not motor everywhere so outboards suited his sailing preferences (& mine). But it proves u can Beach a daggerboard cat easily. Mini keels suck, cheap cop-out.
With mini keels, when grounded you are stuck.
With a flat bottom you have a chance of sliding off.
5-15 degrees pointing difference is HUGE! Seems misleading to gloss over that or play it down. Definition of windward: "Where we want to go today."
Yeah, thats a literal drop in VMG by like 50%
I remember a light air race once in Geograph Bay, where a mini-keeled cat was doing what I assume was about 1 knot VMG while our similar sized and rigged cat was doing about 5 knots VMG, we triple lapped it in a race which they didn't even finishing. They ended up selling the boat after and buying a boat with daggerboards after the trip from Geograph bay to Perth (200 kms) took 4 days while the trip took us 12 hours.
15 degrees!?!?!?! Holy cow! Balance cats has some really nice DB boats, some where they don't protrude above deck. Some loss in storage in the hull lockers, but otherwise, a passenger would never know the difference. Great time to be alive, well, except that entire 2020 thing. :-(
"have" ... grammar police be easy.
@@Kruncher55 Some daggerboard trunks are essentially invisible (for example if integrated with the outer hull), though even if well integrated, they will take some space.
Another excellent discussion. I understand that some would label me as a heathen but I wonder if a centerboard incorporated into a shallow keel structures on each ama, similar to a Garcia, would offer similar performance as daggerboards but reduce the chance of severe damage with touching bottom. I was hoping that he was going to touch on that but I may have been the only one thinking this way.
Looking forward to more of these. Cheers
I was thinking thre same thing!
Hi Nick can you turn that iTec book round the right way please it’s messing with my OCD 😂 love your channel 👍
LOL, I must be some OCD also. I know it's there, seen it in all the episodes, but I'm guessing that they have moved on. I believe that is his parents house where he was during the lock down / quarantine. ast time I had a position check (ways back), they were in southern France back at the boat. Episode 114 end of June / Beginning of July
Me too! German Verbs ... I think I have that same book!
Hahaha
I have a question?, what if you design a cat with mini keels (for protection of the sail drives) which has a retractable "daggerboard" which slides/folds inside the mini keel, would there be advantages to such a design and would it make a huge difference in the pointing ability of the boat?
Yes, there would be an advantage to having that configuration. Sounds like centerboards.
I know it wouldn't work for a cruising cat but you have to have seen the shape of the Hobie 14/16 it was truly revolutionary for its time and really addressed the dagger board need and boy do they point!
Er - Hobie's were the worst pointers ever. I raced Hobie 16's and switched to Cobra 16' cats and then stingray 18' cats and we'd always laugh screaming past a Hobie at +25% speed and pointing 25 degrees higher lol. They were good off the wind in choppy seas - less likely to bury the nose - but going to wind wasn't their thing. The 18' Hobies introduced daggerboard precisely to counter that problem. The 17' Hobies (single handed racing) also had daggers.
I really enjoyed that discussion. Call me crazy, but it seems to me that if a catamaran was designed to have much smaller daggerboards closer to the bow-knuckle that it would increase its pointing ability working in conjunction with the rudders? I don't see this anywhere, so perhaps there a reason for it, it just seems as though it might be an interesting future design? They would also be located in an area of the hull which doesn't consume livable space. Thoughts? On a side note, The little lady looks so good as a result of having those extra weights on board. The price we pay for love.
With respect to your designer--hull forefoot and topside angle has bugger all to do with leeway prevention. Of course the leeward bow is going to be in the water and John Shuttleworth (a damn fine designer who really knows his stuff) designs all have a knuckle coming out of the side of the boat--like Pescotts, and both these boats go to windward like a train. Shuttleworth also has very good evidence that you only need one daggerboard--loss of performance is aorund 1-2%
Re daggerboards why then does Seawind make the 11.90 with daggerboards and market this as their performance boat?? A Pescott catamaran against 1160's (same length) wins by over an hour in round the bouys races in Sydney harbour. 5-15 degrees to windward is significant!
Weight is mighty important to performance, however even a light boat with mini keels is not going to go well to windward. You're splitting hairs, if you want a great sailing boat especially to windward go for daggerboards. If you're not worrying about performance let alone windward ability go for mini keels.
I'm not sure they explianed those points very well at all, and am not sure too many people are aware of the benifits of single dagger board design. A deep dive might have also included center boards (especially considering RR is a Southerly with a retractable center board). The advantages of dagger boards regarding manuverability was also lightly touched on.....feels a little like he was trying to justify the mini keels....I personally would have preferred a more frank and complete discussion on the compromises and ultimately how the Seawind 1370 meets their criteria. But in the end not about me, think I'm reacting to the click bait
Yes, and I worry that Nick is going further and further down a hole with this naval architect. “We want a cat that can sail as well as a monohull” just betrays sloppy thinking and fairly dense reasoning and makes it seems he is just trying to justify his choices. You simply cannot have a truck that drives like a Porsche- they are fundamentally different. It would be so much better if instead of Nick trying to dummy stuff down and justify himself, as well as lead and prod the naval architect, that he gets someone with serious history in yacht design on. Shuttleworth, Woods, Kelsall, some of the many NZ. Nivelt in France has more boats under his belt than dinners (maybe :).
Agree, even a couple of degrees higher pointing can make a lot of difference at the end of an upwind leg, assuming you're not losing VMG by pinching. But cruisers pick their passages and timings to avoid upwind if possible, so it's less important. More significant for me is that mini keels don't work at slow speeds, so you end up motoring when you could be sailing :(
@@bluemu if you can convince Sailing Millenial Falcon to get onto this topic I think we'd be in for a treat. Adam is an aero engineer, and like all us good engineers, he seems to be unable to help drawing diagrams and geeking out over resultant forces and bending moments. I think most viewers probably come for "sailing channels" and want to learn a little, versus people who want a deep dive and are happy when a boat design question somehow turns into five hours reading through boatdesign dot net forum (or is that just me?)
Seawind model 1190 is available with boards or keels depending on what your primary use is going to be, you should try and get to sail on both to compare, I reckon Seawind would be keen to make it happen.
I'm a racing sailor so would want boards except for going aground or hauling out. Choices!?
Primary purpose of daggerboards is to access shallow berths. Pointing is a bonus.
I would rate both about equally.
I think the pointing/performance is by far the best part of dagger-boards. After all, your sail-drives and rudders will be almost as deep as the mini keels so getting rid of the keels doesn't buy you much draft reduction.
Hi really enjoying your journey and adventures in your 2nd interview on daggerboards one aspect was not covered and that is the comparison of the tacking ability of the two. Can you address this in your next interview as it is one more piece of the puzzle towards a decision which is best for me but at the moment leaning towards daggerboards.
Love Technical Tuesday!! Thanks for another overload of information Nick!! I always questioned to have either daggerboards or mini-keels on the cat I plan on getting in the near future. Fair winds and following seas Ruby Rose !
That guy is a catamaran hull designer? I have shoes that are older than him. I am not saying he's incapable or that his young age is bad, is just that I'd think he would be a 2nd in command or something. I'd like to know what program he uses for cfd, computational fluid dynamics. I'd really love to see a couple of his and other designs and see the pros and cons of different design elements and how they affect the whole b&oat. Plus how the weight balance of gear can affect performance. CFD is a powerful and enormous time savings tool and we as consumers are getting huge benefits from it.
Thank you both. Looking at the polars it really does look like max VMG is no where near the highest you can point. It would be great to see a discussion of downwind strategies and downwind-polars with a symmetrical kite, goose wing jib+ code 0, vs gybing downwind with a code-0 only. Not just speed and VMG, but also comfort and other factors how a catamaran is designed to go downwind best.
Thanks Nick!
Quick question: He stated that dagger boards increase your upwind performance by 5-15% or was that 5-15 degrees? And it that the total improvement? (ie. 5 degrees closer to the wind on each tack for a total of 10 degrees improvement?)
We have just chartered a Seawind 1260 out of Key West and had to sail to windward both to and from the Dry Tortugas (Murphy's Law!). When trying to sail to windward 5 degrees on each tack is a _huge_ improvement. The boat would sail at 39 degrees off the wind but we were slipping to leeward by another 6-7 degrees. To be fair the was current in the area and it was hard to judge the magnitude of the effect from the current.
We had to motor-sail to get home and I felt that 5 or 6 degrees better windward performance would have made a huge difference.
Are there any numbers comparing the windward performance of the 1370 to the 1600? I know they are different boats but it would be nice to see the trade-offs in a real world example.
GREAT job!
~Peter
So I'm gonna paraphrase and some one can tell me how I'm wrong. According to Antone' the faster you go, the less daggerboard you want in the water. Since the daggerboard gives you a 5% - 15% ability to point higher, that would mean one of the following is true. As you pull up the DB during higher speeds, you lose the ability to point as high, and you need to fall off the wind. Or, what I think is more likely, as you gain speed you can point higher w/o a daggerboard, gaining back that missing 5%-15%. thoughts?
a wing generates more lift the faster you go (up to a point), a daggerboard is just like a wing - it generates sideways 'lift' so the faster you go, the less wing you need in the water. But having anything in the water also has drag, so lifting it up reduces drag, so your speed can be better, which means more effect from the daggerboard. So you can see why it makes sense they're adjustable to adjust the amount of effect you need from the daggerboard to match the speed.
@@quickdry3 Plus he made it sound like you don't need as much daggerboard at high speeds / high pointing if your bows stay wet; you'll still track ok and can cut daggerboard drag by lifting.
@@afterexposure right, (I'm not a naval engineer/architect), but ignoring any effects from hull shape, when the bow is out of water the length at waterline has decreased, and it's also moved the sail's centre off effort forward relative to the boat length at the waterline
Infusion techniques. You old scientist you... Nick, at last... proper scientific discussion of tea making process 👍😂
Love the series, love all the Tech Tuesdays... but (@ 08:26) CJ (my lady) looked up and exclaimed, "I want to hear more about the talking daggerboards!" LOL
As we said love everything you guys do! Sorry to say we are dyed in the wool old school monohull sailors, and are not ourselves interested in Cats, but we just may keep watching when ya'll disembark from RRI for RRII. Good luck!
Thankyou for the video. It was very interesting and reminded me of the Delos video they did with Amel's designer.
There is a lot to know and we''ll probably never know it all.
From the Delos video the designer got into sails which I found more interesting as they are something the average sailor can influence unlike hull design.
Whether you're sailing a cat or mono they all seem to squat at speed and this I learned was due to lift created by the headsail. It makes for a more comfortable and drier sail as I guess both boats use that lift to plane more on the beamier part of the hull which kind of ruins the theory of hull profile preventing drift to an extent.
Your designer was struggling with English but that's fine because no one has heard my French. Please thank him for his time.
The mini keel also protects the shaft or sail drive, as well as the rudder.
Firstly, congrats on a great channel, always look fwd to new content. A couple of thoughts on daggerboards: the argument for daggerboards on a cat is the same as for having a deep high aspect fin and bulb on a cruising monohull. Both would improve windward performance, but other compromises make more sense on a cruising boat. It's possibly arguable that leeway on a cat when the force component of a boat going hard to windward is lateral, adds a safety margin. A cats lower inertia could make it more tiring beating into a chop, too.
Sailing ability is 100% science.... The art is to make the thing livable.
Land lubber's opinion.
Most methodical approach to a boat purchase I've seen. All documented on TH-cam episodes. A year or so when we're all on that Seawind sailing, it will be worth it.
Great 2nd part in this series . Informative and answered a lot of my questions . Thanks for sharing . From Steve Stott in Sutherlin Oregon U.S.A.
Thank you so much for this. As a non sailor much was over my head, yet it was made so understandable. Antoines grasp of technical English is amazing and the whole subject absolutely fascinating
I was a Hobie Cat sailor back in the 70s, you ever look at the hulls? no dagger-board, no keels and they haul ass... wonder why no one has made a bigger cat.... used to ride the surf with the Hobie right into the beach, the rudders would kick up..
Wharram Designs seem rather close to Hobie Cats
I would love to hear more comments about the deep vee hull shapes (lateral resistance) and double ended cats (seagoing ability) of the Wharram designs. Looking forward to watching you build with much interest. Thank you for sharing.
Deep V has many disadvantages.
They hobby horse, which kills the airflow over the sails.
The centre of lateral resistance, on the hull, is far forward and changes with speed.
I enjoyed this, information was quick and understandable. Basics are clear here, I would like to see the hull shape with a mini keel, is it more blended or more flat to the side load of the keel.?
Certainly GunBoat and other performance cruising Catamarans shed weight by using carbon fiber everywhere and they are very expensive. As Antone stated a Daggerboard cat that is light will point 5 to 15 degrees higher than a similar hull with a mini keel. We know the giant huge wetted surface cruising cats could not use daggerboards, it would be like putting lipstick on a pig. The same can be said for putting minikeels on a carbon fiber low wetted surface catamaran hull. If you want to sail downwind in a whale go with minikeels. If you like pointing higher and going upwind at times then get a catamaran with light hulls and daggerboards. It is as simple as that.
Hi nick, a question for Antoine if possible. What were the main errors that designers made 20 or 30 years ago in cats?
👍👍 I have learned a lot listening to y'all on the pod cast. Thank you for sharing.
8:14 It's no a coefficient of 2, it's "the lift is proportional to the speed squared"
A coefficient of 2 is the same as “squared”
@@sailingrubyrose not exactly. If the speed is 1.5x, then the lift is 2.25x rather than 3x
@@sailingrubyrose en exponent of 2 is the same as squared , a coefficient is a multiplier , not a power
@Sailing Ruby Rose sorry Nick but @Serhii Almazov and @Gerrit Govaerts are correct. Glad someone caught this. Made my engineer's brain twerk when I heard it. Back to school with you! Hope you are learning as much as we are from all this. Thanks for this series and really look forward to seeing the boat in Annapolis or Miami one day.
Sailing Ruby Rose nope.
F=2x 2 is a coefficient
F=x^2 2 is an EXPONENT
I really enjoy these videos and find them quite educational.
The extra kts running from a storm is definitely handy 🤷🏽
Really appreciate these conversations, but so many ads in addition to Patreon and a deal with Seawind, are they that necessary?
Really interesting series even for a motor head like me! 🤯
Sorry, Didn't find that this video increased my understanding of Catamaran designs and daggerboards. I do understand that it is more complicated than I had assumed, but I was hoping to better understand draft and grounding considerations and how wind speed affects the tradeoffs. I guess I was looking for the easy way out.
Great video! Question for you guys;
Why did you decide to go with a completely new 1370 vs a 1260? What about the 1260 didn't you like?
Great stuff!!!
Maybe this is address farther down in the comments but it was mentioned that daggerboards help rudder reactivity. Does this relieve pressure on the rutter? If so, that seems very beneficial not only to upwind performance but decreased stress on the rutters' mechanical components? Am I wrong?
Also centerboards are much lighter than mini keels. And weight is critical on any boat but especially a cat.
Dazcats offer the use of deep foiling rudders. I wonder just how much more pointing this provides.
It definitely makes a difference - I sail one.
Thanks. I've always wondered.
What are the expected consequences to the integrity of the boat when hiting a rock, reef or floating container whith both systems? (Minikeels / daggerboards)
How much weight do you have to lose in order to catch up with the 1-2 knots advantage of the dagger board?
From the comments below daggerboards have so many more plus points than mention in video
Is there a catamaran that uses an A-Frame mast such and on the Rainbow Warrior III (a monohull,) would such a design have advantages?
Hello. We have a Gemini 105 M. We are converting it to the power (mast removed). We’re trying to figure out if we still need the centerboards. We already removed the rudders. Installed 2 yamaha f70 motors. Purpose-crossing from the Miami to Bahamas. We cant figure it out. Manual says that it is not recommended to use them while motoring due to the drag. Is there any purpose in them for our use in it? Those are 300lb each. So looks like unnecessary weight.
Thank you.
Nice Vid. Now ask him about Tri's. Really curious about those things. Seems like a no brainer to me based on all the things I've heard about them.
If you put only one daggerboard in Catamaran, what will bei the effect?
"60% art and 40% science." "That's a good way to go through life..." Nick and Antoine, you nailed it. Profound.
Is this why some cats back side sits deeper in the water versus the front of the hull?
Great discussion guys!
the chord length of most catamaran dagger boards are not long enough for their speed upwind, longer chord length would give better upwind pointing ability
Not true! A deeper board with LESS chord will always have more lift. Longer chord means that it takes more boatspeed to get smooth flow from the front to the back of the board, and you need the smooth flow to start creating lift. So longer chord needs more speed, but at this speed a deep, narrow daggerboard is creating massive lift, so you can lift it up and reduce drag, and still have enough lift!
@@sailingstar8182 My statement is true, read what I wrote again. You are discussing something I haven't mentioned, chord length is to be matched against the boats designed performance, would your design scenario make a lagoon perform as you suggest? Longer chord length gives better pointing at slow speed, shorter chord length at high speed.
How to integrate a swath, swath2cat, or norstein x-bow, or even retractable foils assuming it can be safe, hull design Into a 55ft catamaran - to help manage sea state?
Is that guy a high level designer ? I had cat with mini keel, sold it after 4 months for one with a daggerboard. No pro will sail without dagger board. I would preferred him saying 60% hitech and 40% art.
"SPEED TO LIFT RATIO. As the speed doubles, so the lift quadruples. A coefficient of 2".
He says "quadruples",
perhaps he means speed in power 2 and not speed multiply by 2.
speed**2 and not just 2*speed
Thanks for a great informative video. Don't you think that pointing ability is only really needed when you racing. Cruising around the world, pointing doesn't really become an issue? Time should not really be an issue either. Enjoy all your videos.
Is not time, is how much you will use diesel.
Time becames safety when you run away faster from troubled situations, such as weather traps.
Did i hear that daggerboards increase speed 1 to 2 knots?
More interested in foils for cats than daggerboards.
this is good content
What is "hull shape?" Prismatic coefficient? Hull beam? Hull draft? Wetted surface? The designer is puzzled because the term is not used by naval architects.
Nice info.. I love mini keels if the protect the prop and rudder .
But cats with dagger boards are very nice to have.
The dagger boards you don’t need to use them al the time.
It’s nice going sharp to the wind.
Or if the sea states is not stabilising your boat.
So having daggers ., it can be a very nice tool .
Obviously you need some de discipline to check of there up in shallow water.
I've seen people have great success upwind on cats with a larger roach on the mainsail.
great video , but I would loved to have also included in it the centerboards . It seems that centerboards is in between daggerboards and mini keels why aren't they almost used in catamarans?
add C-foils to that
@@gerritgovaerts8443 lol I'm trying to imagine a floating apartment like a Lagoon flying a hull and using C-foils... I suspect they're all purposefully kept out of the equation since a cat can't heel and 'wash' off wind force the way a cruising mono can, tools to really load them up would suit racing, but even performance cruisers in general seem more cruisers with better performance, not performance with a little cruising - like the "Fancy SUV in the suburbs", the closest to mud it sees is a dirty puddle, but at a push it could drive on the beach - performance cruisers cats can go faster, but not designed for the loads of racing.
Pointing starts with an immersed bow? So why dont they put the daggerboard nearer the bow where it doesnt have to be that deep while retaining the mini keel near the center, or is this a stupid question ?
Our Seawind 1160 sails at 32° apparent. The 1190 Em with daggerboards does the same. The only difference is leeway. The difference measured at Hamilton Island Race Week is 2° only
That’s the sort of stats we want to hear! Cheers
...at what windspeed and boatspeed do you get similar pointing? That's critical, because mini keels don't work at slow speeds. And sure you can point, but what's the boatspeed at 32 degrees apparent? Because the forward drive comes from the keel lift (not the sails - they just push the keels sideways, or slantwise, which then pushes the boat forwards). Daggerboards will always have more lift potential, which always means more boatspeed. Sure you can point at 32 degrees with mini keels, but you'll be going slowly, and sideways, unless there's plenty of wind to start getting lift from the LAR keels. Don't kid youselves - sail both types and find out for yourselves!