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Your rolling action you showed was actually a trimaran. It is very different between a Cat and a Trimaran. Also other disadvantages are bow diving, which is a huge issue with Catamarans and hull slamming in rough water and high waves. Hull design is also very important so you do not get hull slip like Austals - where with a sharp bow and flat aft sections and water jets, the hull's stern can slide from side to side causing sea sickness due to horizontal yaw motion - instead of the normal heaving or roll motion of a ship. There is also added hull resistance due to wake interference between the two hulls.
I would love to, but that is very hard question to answer. It's similar to asking the cost to raise a child. Every ship is different. But to give an overly simplified answer, the engineering costs are typically around 7-10% of the total build cost for a medium to large ship. For advanced vessels or anything that requires new technology, that cost may go as high as 25% of the build cost. Smaller vessels are really difficult to price fairly because we have a basic level of engineering that we can't cut back on. I once worked on a team to design a small 65 ft fast boat. We had around 15 engineers all working. On that boat, the engineering was probably 150% of the total build cost. Thankfully, the yard was building 50+ copies of that boat, and they could distribute the engineering costs across all the copies.
Mr. Mark Fryer- Great idea, but as Mr. Nick pointed out, you have a weight issue. Drilling platforms like the semi submersible quads and drill ships all use ballast tanks to lower their center of gravity by lowering the vessels deeper into the water. This adds stability, but they also use a very reactive system to hold the vessel in place and counteract the dynamic forces of seas and wind. This system is called Dynamic Positioning. It uses satellite based signals to control a series of thrusters to hold it in position. The sensors on the vessel itself measure the current speed, wind speed, pitch and heel/ yaw angles. These measurements provide feedback to the system which causes the thrusters to react. You'll see vessels like this sunk down when on sight, but during transit to get rid of the added resistance, they have to pump off the ballast. It's actually kind of weird seeing a semi sub out of the water traveling just like a normal boat lol Anyways, not knocking your idea as lowering your center of gravity is always a great idea as far as stability goes. Just providing some insight on these types of systems. I hope the information is useful. Cheers.
Have you heard of the SWATH design? Seems to be based around placing a catamaran on top of submerged hulls (basically submarines supporting a surface vessel) It has it's own up and downsides of course... You don't get the speed advantages of a catamaran, more complex, requires more maintenance, lower load carrying capacity... But... You get far more in the way of stability and much less effect from waves...
The worlds largest cat was a very large ferry on the Irish sea. Just could not operate in moderate weather. Commercially, a disaster when the regular ferries were sailing and she was laid up waiting for the fair weather.
I would not recommend it. The wide hull of a catamaran means the roll motion has much more torque behind it than a monohull. You would need a much larger gyro stabilizer to be effective on a catamaran. A better alternative for catamarans would be bilge keels or stabilizer fins. Both of those become more effective as the ship gets a wider beam, which plays right into a catamaran.
You didn't mention slamming. In heavy conditions the nominally flatter crossdeck is subject to some pretty heavy impacts that can't be dissipated, particularly as the amas can dive more effectively through the mass of a wave.
I've been looking into those luxury catamaran yachts (like the Sunreef 80) a lot lately, purely out of interest. After your video on hull shapes I noticed that they have an axe-bow. All the weight is to the rear and the amas are very long and sharp. They manage to get those 45 ton beasts to plane as well, as you explained one can do with an axe-bow. I'm learning a lot ;-)
i would think a Quonset Lattice, would greatly reduce stresses enough in the crossdeck, where we would have seen that employed in Catamaran design. ( so the crossdeck is more just tensile ) i guess the trick, there, would be craning in the rest of the parts though and around the arches. but it could be as simple as One Arch-X .... that would reduce stress in the cross-deck quite a bit.
Once rode a catamaran ferry from Denmark to Norway. First ride was BAD, we had a moderate storm and the ship was moving all over the place. Up, down, left ,right so bad the plates of the kitchen were flying out of the closed shelves. And half the passengers were on deck feeding fish or on latrine duty... Ride back was nice.
That was the Fjord line catamaran betweem Hirtshals and Kristiansand. As you you say catamarans are crap even with moderate waves. That is also why they only use it during summer season. Only monohull ships has the capability needed for a year around service.
How about catamarans made using submersible hulls? You only tend to see submersible hulls on large oil search and drilling platforms but they could provide a solution to rolling problem for catamarans.
You are right. This is called a SWATH: Small Waterplane Area Twin Hull. Just as you said, the idea is to put most of the buoyancy in a submersible hull and stick it completely below the waterline. You then have very narrow struts that extend above the waterplane to connect with the main deck. They work very well. You normally see these on vessels that want to minimize seakeeping motions. As you said, drilling platforms are a great example. The one catch is that because these are so insensitive to passing waves, you need to focus on more active control systems. A normal boat may ride up a large wave, but a SWATH will ignore the wave until the main deck gets slammed. Weight is another issue. People love to put extra weight on ships. Spare parts, spare cranes, supplies . . . it all adds up. On a SWATH, those weight changes quickly sink the boat deeper in the water. So you need a larger ballast system to compensate for any weight changes. Brilliant idea!
Also, what of using Catamarans or Trimarans for large cruise-ships? These normally rise quite high out of the water, with cabins stacked many stories high: and the extra deck area provided by a wide cross-deck should, in theory, allow for a "flatter" superstructure with less structural material invested in supporting the vertically stacked weight (somewhat counterbalancing the extra structural costs for the wider cross-deck underneath the superstructure...) Right?
My favourite naval architect, so I have to respectfully advise how to solve catermaran problems: add a third hull like a lakatoi so its a tri-form hull. I did, it works.
Hi there. I am curious. Does the presence of a second hull mean that the portion of the bow waves between the two amas are smaller due to the two waves cancel out each other?
Actually, it depends on the spacing between the two hulls. The waves from the bow of each hull spread outward. If the hulls are set at the wrong width, then those spreading bow waves can add to the stern waves. That actually increases the waves between the two amas. Or if you get it right, the two waves cancel out to reduce the total waves. When we calculate resistance for catamarans and trimarans, we introduce a whole separate set of coefficients to deal with interactions between the amas.
Great idea! I'll add it to the list. Short answer for now: Trimarans are good when you actually need to support some weight, and you are governed by stability. The two outer amas of the trimaran add to the ship stability, without adding much resistance because they are so skinny. Cons: Higher build costs. And more difficult to fit propulsion machinery into such a tiny hull. I'll work on providing a more complete answer in a later video.
Awesome, thanks for the info. I'm looking for the best hull design for a 25m solar electric boat to cross oceans. The options I can choose from: -Displacement mono hull -Catamaran -Trimaran I'm leaning towards a trimaran hull design. The hull should have the least amount of drag and be as fast as possible with limited power. Trimaran have the most deck surface to fit solar panels and I think provide the most stability in rough seas. I also think a trimaran looks a bit cooler than a catamaran. Whats your opinion? Maybe you could even do a video on what would be the best hull design for a solar electric boat!
I would consider either a trimaran or a catamaran in your case. At 25 m length, stability will not be a huge concern, assuming you are only carrying people. With solar power, I think your main concern will be minimizing your wave resistance. You can always go slower to minimize equipment weights and solar power needs. But you will hit a minimum power needed just to overcome the ocean waves and wind. Anything more specific depends on details of your case. You can email me at n.barczak@dmsonline.us to get into more specifics.
Trimaranas, logically should be even better from a resistance standpoint, as you can distribute the needed buoyancy in 3 hulls instead of 2 (making for a skinnier hull). Also, the central hull will likely never rise out of the water with a strong side-wave, providing a bit more stability in certain situations, correct? Plus, trimarans have 2 shorter cross-decks. And, potentially, can ride higher in the water while keeping the ama's thin- leading to more room between the waterline and top deck for a wider (and therefore, boxier/stronger with hatched cross-supports) cross-deck...
It terms of sailing catamarans. They seem to want to pitch in waves. Would control fins help this and rolling? In the pass trampolines in the bow area helped reduce the weight of fiberglass boats but would carbon fiber or aluminum boats theoretically benefit for a solid cross deck structure.
Yes, control fins could potentially reduce rolling and pitch motions. In fact, I found a paper from the 1960s (early days of commercial catamarans) which described how to use a hydrofoil solely to reduce pitch motions. The hydrofoil provided no lift. It was positioned about halfway between midships and the bow, stretching between the two amas. This acted like a door hinge, moving the pivot point for pitch farther forward. Moving the pivot point gave more leverage for the buoyancy of the amas to resist pitching. As to the second question about the trampoline. I don't think the solid deck would help. I have heard many reasons for the trampoline forward, and none of them completely match my knowledge of ship design. From what I do understand, I think the trampolines exist mainly due to underdeck clearance. We don't want the waves to slam against the underside of the hull. But a high underdeck clearance means a tall catamaran, with more windage and more expensive hulls. The trampoline is a way to reduce the required underdeck clearance. We need higher clearance forward, because of the pitch motions in the boat. If we put a trampoline forward, the waves can pass through. That reduces the required underdeck clearance. And the problem of underdeck clearance remains true, even if the boat is made from carbon fiber or aluminum.
@@DatawaveMarineSolutions Thank you. Good engineering is creative. The sheer number of variables is impressive and the balancing of solutions brings this field almost to an art form.
Back in late 2019, I attended a powerpoint party where everybody made a powerpoint presentation about something they were really interested in and knew a lot about but never got the chance to talk to people about. I'd really love to see what Nick would come up with for that that ISN'T in the realm of naval architecture.
thx. but which brand of power cat is gd and reliable for rough sea? my single hull Striper getting too rocky at time. my parents can't take it at time.
If you place the majority of the buoyancy in the arma BELOW the surface with only small vertical 'struts' joining them to the hull above then it is possible to improve on what you have said.. This also reduces roll angle acceleration, at least until the lower edge of the 'above wave' hull actually pierces or meets the water surface. Extra loads and bending forces come into play as does height that may be required above the water surface so this is another limitation to be considered. Nothing comes for free. You can also add underwater foils to the sides of the arma to provide even greater stability, at the expense of increasing the ride height clearance required.
Yes indeed. The wave systems between the different hulls interact, resulting in 3-5% extra resistance. Only our penalties are based on interactions between water waves. We get both constructive and destructive interference patterns. If you carefully pick the spacing of your hulls, you can get destructive interference and actually reduce the resistance slightly.
This is an interesting discussion as the monohull and the catamaran can have a lot in common and so one prefers to chose the catamaran for various reasons. A single hull where the centre of gravity is always below the centre of buoyancy, well for rough seas and safety, whatever one says, one cannot beat that formula and I would chose it anytime for cruising in comfort and safety. Those single hulls where the centre of gravity is above the centre of buoyancy well they are stable as their mid section is arranges such that the centre of buoyancy will move out laterally faster than the movement of the centre of gravity. In a large ship this is normally chosen to be about seven second period as any faster would mean that the ship will be hard on the hips of the passengers. In a catamaran the rolling motion and lateral stability is rather fast and while a person travelling fast on a short trip of an hour or two sitting in a rubbery comfortable seat could take that punishment well the joining deck in a catamaran especially in a diagonal action of the waves, that will subject the structure to enormous forces and stresses and one needs to spend a lot of time considering the investments in the cross structure of a catamaran as long heavy journey could play havoc on the structure. Capsizing of a craft that has its centre of gravity above the centre of buoyancy is very dangerous as it will float upside down, so before any long journey such crafts must watch the weather conditions......... but profits and economy and convenience makes a man decide on what is less safe ......... but good engineers minimise but do not solve the risk in question. So what ever Nicolas Naval Architect says, he has to swallow the fact that catamarans could be very unsafe in certain conditions and a single hull is better. Now with powerful engines and catamarans reaching well over 40 knots, the catamaran may make port much faster than a single hull which needs to face it all alone in the wild sea. I have contact with fast powered catamarans and one must admit that the 7,000 to 9,000 Horse power engines be they jets or pistons well they need constant expensive maintenance as speed is only related to the rate of fuel burn and materials are being pushed to the limit in a catamarans, be they the mid section structure, the exhaust valves on high revving diesel engines or the stator and turbine blades of a jet engine. The manner we are using material to its limit is so scaring and so as a private individual who wants to cruise in safety and in a relaxed manner, one may opt for some weight under the hull and an old fashioned sail shaped to take the natural wind.
Carmel Pule, Interesting perspective, and some valid points raised. Although I respect your individual choice in vessel, a rag powered concrete-dumpling isn't my cup of tea, but then neither are tweed jackets and scrapbooking. The bit that seems bewildering though, is the seemingly 'tut-tut' overtone regarding any pushing of the boundaries and exploring the limits of materials, designs, construction, and propulsion. I'm happy to be wrong, but my gut says that the music is already way too loud
Don't monohulls capsize much easier AND they sink because of the ballast? While catamarans are much harder to capsize and then float upside down as a life raft. So are much safer. I'm curious about a good comparison of the motions though.
for Cross ocean trips.. does the deck width have any real impact on speed? Since you still have 2 hulls in the water, I assume the deck width only impacts speed due to weight? of course, its riding waves get impacted, but lets just stick to the speed variable. I guess weight is the one variable that impacts the speed in this case?
Weight is one major element. For catamarans, the other impact on speed is wave interactions. Each ama produces its own wave system. As those wave systems spread out, they overlap and interact with each other. They can interact to increase the total resistance or decrease it. We prefer to set the width of the cross deck so that the interacting waves reduce the total resistance slightly.
Summery of entire video: Talk to a naval architect for actual information, but click the like button even though the video contains no actual information, and he will make more equally informative videos.
2 questions: * Would X-bows better keep both hulls in the water on larger vessels? (I’m sure the leading face of the aka would have to be shaped to push greenwater beneath and to the sides). ** Do catamarans’ sterns elevate as the vessel makes sharp turns? (On a smaller scale, Ithis happens to the twin-hull Livingstons.)
I always feel like I'm about to watch some sort of late night B movie or obscure music video on this channel. Like, strong public access cable channel vibes. Anyone ever seen the channel on YT "Whitecastle at Midnight"?
Do smaller power cats like 30-46 feet avoid the cat slap in rough weather by powering forward and coming down on a cushion of trapped air between the hulls?
To the best of my knowledge, no. The opening on the front of the cat is too large. Even when powering forward, it doesn't compress the air cushion sufficiently. When the water rises up, the air just rushes out without offering any major cushion. You still get cat slap.
If you use wave piercing hulls with a teardrop shaped cross section that is narrow at the top, can that help mitigate roll? Or mitigate the violent roll? By the way, why is the connection between the hull and the big cross-platform rigid? I guess the forces are too big to make something like a car suspension? Or if you look at how tank wheels are sprung and damp, why can’t you have many many small little hulls behind each other on each side? I mean Ama, not hull.
Yes, the teardrop can theoretically help to mitigate roll, but not any significant amount. There was an experimental craft that did use a suspension connection between the hulls and cross deck, but I believe it was only successful on small craft. We don't do multiple hulls like the wheels on a tank because each hull would have its own bow, which produces a LOT of the resistance for the whole hull. Ships are efficient because we get the parallel mid section virtually free of resistance.
what is the working principle of catamaran please share with me all details related to catamaran like working principle, hull form, stability, resistance , powering , material, propulsion. i want this all point of catamaran so please help me its my project so i am from india chennai.
Hello, If i may peak your interest regarding this subject of a catamaran and going all out geek. Would a battleship or a battlecruiser be capable? Lets say the peak era, of between ww1 and ww2 Using 15 inch main gun turrets, triple or double barrels and be constructed with modern day knowledge and science. If a monohull of that era was like 40-60k tons, what would a catamaran or trimaran be like? Would it be 80-100k?! Meaning adding 2 of the same ship and bridging them? Remember it needs to be armoured and capable of taking the gigantic turrets. What would be the handling of a multihull versus the monohull battleship? A video on this subject would be amazing to delve into the fantasy world of what if you were to time travel and be able to decide building one of these in 1940 and fight the germans ?!
The problem with cats is the centre between hulls gets hull slap in heavier weather and can punture or bend of not fully reinfored, this also causes heavy vibration. Checkout the american naval trimarans
they can get slapped when no in heavy wether, all that needs to happen is to surf down a wave a bit too much and the bow waves collide and slap the center
Guys... Does anybody know if seakeepers are good to be installed in sail cats? Is it common to install seakeepers in sail cats? I mean; I wonder if the cat performance could be affected. My concern is that the cat design was made to use wind loads to perform to a specific level so I wonder if adding a seakeeper for stabilization purposes could somehow affect performance negatively. Any idea there?
The secret: get a naval architect. Like meee! :D I'd love to build me a solar powered catamaran "yacht" houseboat. It seems possible and solar panels have become really very cheap. EDIT on year later: For got to say thank you for the great videos! This was really educational for me 1 year ago. It's also surprising to see how many negative comments you get. Your videos are really great to get an overview. The complex stuff you want to learn from written texts anyways.
You read my mind. I bought a 50' sailing catamaran a year ago. Short term plan - refit it for sailing + add 5kW solar and travel around. Long term plan - lose the sails and turn her into a power cat. Around 12kW solar, 2 darrius style wind turbines, and either batteries or H2 storage + fuel cell - or both. Then buy or make 2 electric outboards (that's what my cat needs) and it's done, other than a 12-15kW diesel genset for back-up/emergency. I could maybe do the 'loop' for free, although slowly. Check out energy observer, I just saw this video today - but it's close to my plan.
@@michaelyount3843 Oh wow awesome. I hadn't seen your comment until now. How did your project progress? I'd love to know how you plan to place the solar panel and if you plan to make one big roof. It's hard to fit enough solar on a boat under 50'. Is there any video or a thread on your project somewhere? I hit a few snags but I'm still planning to do this. My plan is to be able to live comfortably with lots of power and travel slowly but for free. I'm currently learning and evaluating different design possibilities. From catamaran to powered proa to hydrofoiling and trimaran. One thing is sure, it has to be light. In the future a kite sail high in the air might also be a way to add propulsion power once you have automatic steering mechanisms and it can also be used for power generation that is more lightweight and cheaper than wind turbines.
There are no physics that stop us from making a catamaran icebreaker. But mono hulls are traditionally better suited. An ice breaker needs a lot of weight, which it uses to ride up on top of the ice and break it. When you talk large weight, monohulls are typically the better choice. That said, I did see a concept design for a trimaran icebreaker. Check that out here: th-cam.com/video/FjRSgUm03tk/w-d-xo.html
Very true, but there are plenty of monohulls that sit comfortably upside down once rolled also. In my mind, once a boat is upside down, it's time to pack the lifeboat, I don't care what kind of boat it is. I've seen what happens when a monohull is rolled, it wasn't pretty. Having 2 ft of sea water dropping on cushions, food, and bedding after dumping the contents of all your cabinets, and storage all over the cabin,... That boat is pretty much wrecked.
Yes they are ! Up to the already mentioned´s ... But yet I keep on wondering where the 1950 ish fantastic high speed at high seas Hydrofoils went. I dont see any of them around. h-Why ...?! I fantasize the stability of a catamaran combined with 4 point lift would be rapid wonders of angry seas.
I am thinking of building a James Wharram design Catamaran in Aluminum because Aluminum is faster , stronger than most Materials used for Boats , no sanding, glue, fiberglass wood to rot no painting is necessary. Building out of Marine plywood wood and Fiberglass is almost double the work and close in price and best of all a hell of a lot less Maintenance and aluminum welding as improved so much and is so much more easy .
It seems you have no experience of boat building. Not a good idea of using alu on old fashion design not thought for alu. The weights will become exponential. Add to the weight of the bare metal hull the weight, work and price of the insulation, mandatory on a metallic hull. You'll be very disappointed.
Excellent point. I tend to focus on the large commercial cats. If they invert, it just became a salvage operation. But for small recreational cats, perfectly normal to invert and then try to flip it back upright.
In France, with our long experience of oceanic sailing multis, we have a proverb that says while multis can float inverted and keep you alive, monhulls will always sink upright. (that's for sailing yachts). In monohull ships a big heel angle is a salvage operation, and beyond a certain angle is a sinking. A capsized motor yacht or trawler monohull will sink in minutes, or at best stay inverted with no refuge for the crew as I have seen while rescuing once fishermen in the sea of Iroise.
Actually, that is a definite plus. A monohull (yacht) that loses its keel and rigging and does not sink is going to be a really really big washing machine, roll roll Of course, most monohulls that lose their keel actually sink. Great stability sitting on the ocean floor.
Excellent point. In fact, we sometimes need to check catamaran stability in the longitudinal direction because of their shorter length. The pitching problem is also why commercial catamarans usually keep themselves 1.5-3.0x longer than their beam. That length to beam ratio avoids the entire pitching problem.
O when I found out sailing speeds up to 20 Knots is possible in a Cat I am sold rather than some big old slow Barge that sways like a tree in the wind , I loved sailing Dinghies then I sailed in big winds and a big boat I did not enjoy sailing any more I think a Cat may be my answer .
@0:55 you claim that the hulls of a catamaran are called "demi-hulls" or "amas". In my 4 decades of sailing, I've never heard either of those terms. I've only ever heard them referred to as "hulls", with catamarans & trimarans referred to as "multi-hull" and traditional sailboats as "monohull".
Yeah, cats are stable. So stable that they can float upside down as well as right side up. In other words, you may have good initial stability, but may have horrible reserve stability. Monohulls can be made self-righting, multihulls never.
Monohulls, catamarans, & trimarans will be a thing of the past. SWATH boats are the most stable boats in rough waters, the high the platform is iff the water the better especially in rough huge seas.
So a catamaran would not be good for a hull design for ships like break bulk ship , container ship, Reefer ships, vehicle carrier ships or dry bulk ships, shame the catamaran is limited to small marine industry segments, because catamaran design does an would promote greater cargo capacities! Umm would a catamaran design be good for a Livestock carrier ship & Semisubmersible transport ship other than gas carriers an passenger ships.
Actually, the Reefer ship and vehicle carrier are both cases where the catamaran might offer major advantages. For example, vehicle carriers really fight against wind to maintain stability, due to their high sides. We have recorded cases where vehicle carriers capsized in high wings, losing all the cargo inside. The catamaran has much higher initial stability and could offer much better safety against those winds. You did correctly identify that all those high deadweight cargoes typically go on monohulls. But I also think there are grey zones, like vehicle carriers. We may find serious innovations just by breaking from tradition. I would definitely try a catamaran for a livestock carrier. Anything where we have passengers (human or animal) is typically a low density cargo. This is because of all the air around the livestock. Think about all that air space over their heads on each deck. Air essentially weighs nothing. That greatly reduces the density. On the other hand, I would not use a catamaran for a semisubmersible transport ship, for two reasons. First is the draft. On a catamaran, we need clear space between the cross deck and waterline. That means the semisubmersible must sink MUCH further down to submerge its working deck. It becomes difficult to find harbors with sufficient depth for that. The second reason is the roll period. As others pointed out, catamarans have a faster roll period. One of the most frequent cargoes on a semisubmersible is a jackup drilling rig, which has truss-legs that stick hundreds of feet into the air. If the ship has too fast of a roll period, those legs will whip back and forth until they break. This is why semisubmsersible companies focus much of their engineering on predicting ship roll motions. You need a very slow roll period for a semi-sub.
@@DatawaveMarineSolutions Thank you for your swift reply and detailed information! I believe catamaran & Trimaran designs promise robust and flexible solutions to the shipping industry well into the future, the advanced monohull designs, im sure will have a bright future aswell! Though I must admit some newer monohull designs are getting quite intrepidly LARGE lately , can the canals & ports world wide keep up with the fast paced evolution of the monohull!🤔😉😁
@@DatawaveMarineSolutions some LNG & Oil Tanker, dry bulk carrier's, Container Carrier's & Passenger ships are getting intrepidly large quite quickly, will there ever be a reasonable & economically sustainable limit to the monohull design!😊🤔 With passenger Cruise ships & Liners, its gotten to the point were there are literally self powered floating cities out there on the Oceans now day's.
@@Blime2913 I hear you about the large sizes. All the major ports and canals are currently renovating to increase their size and depth of their channels. That will happen for years into the future. Great news if you are in the dredging industry. As far as size, I don't see ships getting much larger in the future. I think 1300 ft / 400 m is near our max. At this size, the longitudinal bending of the ship becomes a major concern. It gets so large that we actually need to consider the flexibility of the ship in waves! There are many structural issues that we typically don't worry about at the smaller scale: they become an issue at big scale. That all adds to much more complicated engineering and higher risks for daily operations. Plus, we run into construction problems for these large ships. Imagine a 400 m long ship. That means somewhere in the world, we need a 410 m long drydock to maintenance the ship! For example, the Maersk Triple, one of the largest container ships, only has 2-3 shipyards in the world where it can dock. You can expect those shipyards charge a premium for the privilege, because they have limited competition. In the distant future, ships might get bigger. But we will need to completely re-imagine the ship structure before that happens. We will need something more flexible. Rather than a rigid steel hull, imagine something more like a floating matt of seaweed. Something that contour matches with the ocean waves.
No. I try to add a little drama to keep the videos interesting. I don't think engineers need to be that classic image the stuffy inarticulate lecturer. Though I admit I overdid the drama in some of my early videos. I continue to refine the balance between science and entertainment in these videos.
Lots of space for "low density cargo"....?? What, for my styrofoam and helium balloon collections..??!!! Overload a cat and it becomes a water pig and no faster than a monohull...
Bloody great video, thanks Nick!
Thank you for your useful information!
Great.. now I want to make a 12' catamaran fishing boat. I've just bought a dhingy and started the process of rebuilding it to my liking.
Your rolling action you showed was actually a trimaran. It is very different between a Cat and a Trimaran. Also other disadvantages are bow diving, which is a huge issue with Catamarans and hull slamming in rough water and high waves. Hull design is also very important so you do not get hull slip like Austals - where with a sharp bow and flat aft sections and water jets, the hull's stern can slide from side to side causing sea sickness due to horizontal yaw motion - instead of the normal heaving or roll motion of a ship.
There is also added hull resistance due to wake interference between the two hulls.
Thank you very much.
I like your videos very much =) It would be nice if you made a video series about sail boats. Cheers
Great vids, very informative! Can you make a video about the costs of naval architecture small/med/large vessels.
I would love to, but that is very hard question to answer. It's similar to asking the cost to raise a child. Every ship is different. But to give an overly simplified answer, the engineering costs are typically around 7-10% of the total build cost for a medium to large ship. For advanced vessels or anything that requires new technology, that cost may go as high as 25% of the build cost.
Smaller vessels are really difficult to price fairly because we have a basic level of engineering that we can't cut back on. I once worked on a team to design a small 65 ft fast boat. We had around 15 engineers all working. On that boat, the engineering was probably 150% of the total build cost. Thankfully, the yard was building 50+ copies of that boat, and they could distribute the engineering costs across all the copies.
Smart explanations here!
Mr. Mark Fryer- Great idea, but as Mr. Nick pointed out, you have a weight issue. Drilling platforms like the semi submersible quads and drill ships all use ballast tanks to lower their center of gravity by lowering the vessels deeper into the water. This adds stability, but they also use a very reactive system to hold the vessel in place and counteract the dynamic forces of seas and wind. This system is called Dynamic Positioning. It uses satellite based signals to control a series of thrusters to hold it in position. The sensors on the vessel itself measure the current speed, wind speed, pitch and heel/ yaw angles. These measurements provide feedback to the system which causes the thrusters to react. You'll see vessels like this sunk down when on sight, but during transit to get rid of the added resistance, they have to pump off the ballast. It's actually kind of weird seeing a semi sub out of the water traveling just like a normal boat lol Anyways, not knocking your idea as lowering your center of gravity is always a great idea as far as stability goes. Just providing some insight on these types of systems. I hope the information is useful. Cheers.
Have you heard of the SWATH design?
Seems to be based around placing a catamaran on top of submerged hulls (basically submarines supporting a surface vessel)
It has it's own up and downsides of course...
You don't get the speed advantages of a catamaran, more complex, requires more maintenance, lower load carrying capacity...
But... You get far more in the way of stability and much less effect from waves...
The worlds largest cat was a very large ferry on the Irish sea. Just could not operate in moderate weather. Commercially, a disaster when the regular ferries were sailing and she was laid up waiting for the fair weather.
I was on it in a force 9
Amazing video! Thanks! Will a gyro stabiliser be effective on a cataramran to reduce the rolling motion?
I would not recommend it. The wide hull of a catamaran means the roll motion has much more torque behind it than a monohull. You would need a much larger gyro stabilizer to be effective on a catamaran. A better alternative for catamarans would be bilge keels or stabilizer fins. Both of those become more effective as the ship gets a wider beam, which plays right into a catamaran.
You didn't mention slamming. In heavy conditions the nominally flatter crossdeck is subject to some pretty heavy impacts that can't be dissipated, particularly as the amas can dive more effectively through the mass of a wave.
Less contact with water, but wider flooring for the cab. But in white squall, monohull sailboat is hard to tip over by big waves
I've been looking into those luxury catamaran yachts (like the Sunreef 80) a lot lately, purely out of interest. After your video on hull shapes I noticed that they have an axe-bow. All the weight is to the rear and the amas are very long and sharp. They manage to get those 45 ton beasts to plane as well, as you explained one can do with an axe-bow. I'm learning a lot ;-)
I'm building a 34feet catamaran with out board engines three 350 Yamaha when I'm finished catch me if you can.
you gonna upload any of it?
Looks like Saul Goodman cousin's commercial for boat ! Love it !
i would think a Quonset Lattice, would greatly reduce stresses enough in the crossdeck, where we would have seen that employed in Catamaran design.
( so the crossdeck is more just tensile )
i guess the trick, there, would be craning in the rest of the parts though and around the arches.
but it could be as simple as One Arch-X .... that would reduce stress in the cross-deck quite a bit.
Once rode a catamaran ferry from Denmark to Norway.
First ride was BAD, we had a moderate storm and the ship was moving all over the place.
Up, down, left ,right so bad the plates of the kitchen were flying out of the closed shelves. And half the passengers were on deck feeding fish or on latrine duty...
Ride back was nice.
That was the Fjord line catamaran betweem Hirtshals and Kristiansand. As you you say catamarans are crap even with moderate waves. That is also why they only use it during summer season. Only monohull ships has the capability needed for a year around service.
How about catamarans made using submersible hulls? You only tend to see submersible hulls on large oil search and drilling platforms but they could provide a solution to rolling problem for catamarans.
You are right. This is called a SWATH: Small Waterplane Area Twin Hull. Just as you said, the idea is to put most of the buoyancy in a submersible hull and stick it completely below the waterline. You then have very narrow struts that extend above the waterplane to connect with the main deck. They work very well. You normally see these on vessels that want to minimize seakeeping motions. As you said, drilling platforms are a great example. The one catch is that because these are so insensitive to passing waves, you need to focus on more active control systems. A normal boat may ride up a large wave, but a SWATH will ignore the wave until the main deck gets slammed. Weight is another issue. People love to put extra weight on ships. Spare parts, spare cranes, supplies . . . it all adds up. On a SWATH, those weight changes quickly sink the boat deeper in the water. So you need a larger ballast system to compensate for any weight changes.
Brilliant idea!
Also, what of using Catamarans or Trimarans for large cruise-ships?
These normally rise quite high out of the water, with cabins stacked many stories high: and the extra deck area provided by a wide cross-deck should, in theory, allow for a "flatter" superstructure with less structural material invested in supporting the vertically stacked weight (somewhat counterbalancing the extra structural costs for the wider cross-deck underneath the superstructure...) Right?
Nick I have a boat design, I would like you to review it if the stability of the design is acceptable in your opinion please.
Certainly. Send me an email at sales@dmsonline.us and we can discuss your project.
My favourite naval architect, so I have to respectfully advise how to solve catermaran problems: add a third hull like a lakatoi so its a tri-form hull. I did, it works.
Hi there. I am curious. Does the presence of a second hull mean that the portion of the bow waves between the two amas are smaller due to the two waves cancel out each other?
Actually, it depends on the spacing between the two hulls. The waves from the bow of each hull spread outward. If the hulls are set at the wrong width, then those spreading bow waves can add to the stern waves. That actually increases the waves between the two amas. Or if you get it right, the two waves cancel out to reduce the total waves.
When we calculate resistance for catamarans and trimarans, we introduce a whole separate set of coefficients to deal with interactions between the amas.
Nicholas Naval Architect ok, thanks for the info, nick.👍
Trimaran pros and cons? Can you do a video on that? Very informative videos, thanks.!
Great idea! I'll add it to the list. Short answer for now: Trimarans are good when you actually need to support some weight, and you are governed by stability. The two outer amas of the trimaran add to the ship stability, without adding much resistance because they are so skinny.
Cons: Higher build costs. And more difficult to fit propulsion machinery into such a tiny hull. I'll work on providing a more complete answer in a later video.
Awesome, thanks for the info.
I'm looking for the best hull design for a 25m solar electric boat to cross oceans.
The options I can choose from:
-Displacement mono hull
-Catamaran
-Trimaran
I'm leaning towards a trimaran hull design.
The hull should have the least amount of drag and be as fast as possible with limited power.
Trimaran have the most deck surface to fit solar panels and I think provide the most stability in rough seas. I also think a trimaran looks a bit cooler than a catamaran.
Whats your opinion?
Maybe you could even do a video on what would be the best hull design for a solar electric boat!
I would consider either a trimaran or a catamaran in your case. At 25 m length, stability will not be a huge concern, assuming you are only carrying people. With solar power, I think your main concern will be minimizing your wave resistance. You can always go slower to minimize equipment weights and solar power needs. But you will hit a minimum power needed just to overcome the ocean waves and wind. Anything more specific depends on details of your case. You can email me at n.barczak@dmsonline.us to get into more specifics.
Nicholas Naval Architect Have a look at : www.silent-yachts.com
We offer self sufficient solar catamarans with transatlantic range
4:40 is actually a slender monohull with outriggers (a kind of trimaran) and not a catamaran.
Interesting video.
Trimaranas, logically should be even better from a resistance standpoint, as you can distribute the needed buoyancy in 3 hulls instead of 2 (making for a skinnier hull). Also, the central hull will likely never rise out of the water with a strong side-wave, providing a bit more stability in certain situations, correct?
Plus, trimarans have 2 shorter cross-decks. And, potentially, can ride higher in the water while keeping the ama's thin- leading to more room between the waterline and top deck for a wider (and therefore, boxier/stronger with hatched cross-supports) cross-deck...
It terms of sailing catamarans. They seem to want to pitch in waves. Would control fins help this and rolling? In the pass trampolines in the bow area helped reduce the weight of fiberglass boats but would carbon fiber or aluminum boats theoretically benefit for a solid cross deck structure.
Yes, control fins could potentially reduce rolling and pitch motions. In fact, I found a paper from the 1960s (early days of commercial catamarans) which described how to use a hydrofoil solely to reduce pitch motions. The hydrofoil provided no lift. It was positioned about halfway between midships and the bow, stretching between the two amas. This acted like a door hinge, moving the pivot point for pitch farther forward. Moving the pivot point gave more leverage for the buoyancy of the amas to resist pitching.
As to the second question about the trampoline. I don't think the solid deck would help. I have heard many reasons for the trampoline forward, and none of them completely match my knowledge of ship design. From what I do understand, I think the trampolines exist mainly due to underdeck clearance. We don't want the waves to slam against the underside of the hull. But a high underdeck clearance means a tall catamaran, with more windage and more expensive hulls. The trampoline is a way to reduce the required underdeck clearance.
We need higher clearance forward, because of the pitch motions in the boat. If we put a trampoline forward, the waves can pass through. That reduces the required underdeck clearance. And the problem of underdeck clearance remains true, even if the boat is made from carbon fiber or aluminum.
@@DatawaveMarineSolutions Thank you. Good engineering is creative. The sheer number of variables is impressive and the balancing of solutions brings this field almost to an art form.
You are awsome!
great video
Back in late 2019, I attended a powerpoint party where everybody made a powerpoint presentation about something they were really interested in and knew a lot about but never got the chance to talk to people about. I'd really love to see what Nick would come up with for that that ISN'T in the realm of naval architecture.
Ropes, knotwork, and rigging. . . . It's only tangentially related to naval architecture.
is a 30ft cat stable enough?
could you recommend a powercat brand which could cut wave?
Sorry, I can't make a recommendation for a general catamaran at 30 ft. The stability all depends on the application.
thx.
but which brand of power cat is gd and reliable for rough sea?
my single hull Striper getting too rocky at time.
my parents can't take it at time.
@@zeus-io3hn probably don't date strippers I'd say.
If you place the majority of the buoyancy in the arma BELOW the surface with only small vertical 'struts' joining them to the hull above then it is possible to improve on what you have said..
This also reduces roll angle acceleration, at least until the lower edge of the 'above wave' hull actually pierces or meets the water surface.
Extra loads and bending forces come into play as does height that may be required above the water surface so this is another limitation to be considered. Nothing comes for free.
You can also add underwater foils to the sides of the arma to provide even greater stability, at the expense of increasing the ride height clearance required.
Yes. taken to extremes this is a SWATH design - basically you have the ship above the surface floating on top of two submarines...
Are there ant flow field penalties for multi-hull vessels as there are for multi-wing aircraft?
Yes indeed. The wave systems between the different hulls interact, resulting in 3-5% extra resistance. Only our penalties are based on interactions between water waves. We get both constructive and destructive interference patterns. If you carefully pick the spacing of your hulls, you can get destructive interference and actually reduce the resistance slightly.
This is an interesting discussion as the monohull and the catamaran can have a lot in common and so one prefers to chose the catamaran for various reasons. A single hull where the centre of gravity is always below the centre of buoyancy, well for rough seas and safety, whatever one says, one cannot beat that formula and I would chose it anytime for cruising in comfort and safety.
Those single hulls where the centre of gravity is above the centre of buoyancy well they are stable as their mid section is arranges such that the centre of buoyancy will move out laterally faster than the movement of the centre of gravity. In a large ship this is normally chosen to be about seven second period as any faster would mean that the ship will be hard on the hips of the passengers. In a catamaran the rolling motion and lateral stability is rather fast and while a person travelling fast on a short trip of an hour or two sitting in a rubbery comfortable seat could take that punishment well the joining deck in a catamaran especially in a diagonal action of the waves, that will subject the structure to enormous forces and stresses and one needs to spend a lot of time considering the investments in the cross structure of a catamaran as long heavy journey could play havoc on the structure. Capsizing of a craft that has its centre of gravity above the centre of buoyancy is very dangerous as it will float upside down, so before any long journey such crafts must watch the weather conditions......... but profits and economy and convenience makes a man decide on what is less safe ......... but good engineers minimise but do not solve the risk in question.
So what ever Nicolas Naval Architect says, he has to swallow the fact that catamarans could be very unsafe in certain conditions and a single hull is better. Now with powerful engines and catamarans reaching well over 40 knots, the catamaran may make port much faster than a single hull which needs to face it all alone in the wild sea. I have contact with fast powered catamarans and one must admit that the 7,000 to 9,000 Horse power engines be they jets or pistons well they need constant expensive maintenance as speed is only related to the rate of fuel burn and materials are being pushed to the limit in a catamarans, be they the mid section structure, the exhaust valves on high revving diesel engines or the stator and turbine blades of a jet engine. The manner we are using material to its limit is so scaring and so as a private individual who wants to cruise in safety and in a relaxed manner, one may opt for some weight under the hull and an old fashioned sail shaped to take the natural wind.
I think it really depends on where you are using it and for what.
Carmel Pule, Interesting perspective, and some valid points raised.
Although I respect your individual choice in vessel, a rag powered concrete-dumpling isn't my cup of tea, but then neither are tweed jackets and scrapbooking.
The bit that seems bewildering though, is the seemingly 'tut-tut' overtone regarding any pushing of the boundaries and exploring the limits of materials, designs, construction, and propulsion.
I'm happy to be wrong, but my gut says that the music is already way too loud
Don't monohulls capsize much easier AND they sink because of the ballast?
While catamarans are much harder to capsize and then float upside down as a life raft. So are much safer.
I'm curious about a good comparison of the motions though.
Nick i want to make trimaran out out of existing ship can it be done.
for Cross ocean trips.. does the deck width have any real impact on speed? Since you still have 2 hulls in the water, I assume the deck width only impacts speed due to weight? of course, its riding waves get impacted, but lets just stick to the speed variable. I guess weight is the one variable that impacts the speed in this case?
Weight is one major element. For catamarans, the other impact on speed is wave interactions. Each ama produces its own wave system. As those wave systems spread out, they overlap and interact with each other. They can interact to increase the total resistance or decrease it. We prefer to set the width of the cross deck so that the interacting waves reduce the total resistance slightly.
I want to know about Ever Ace container ship hull design.
Summery of entire video: Talk to a naval architect for actual information, but click the like button even though the video contains no actual information, and he will make more equally informative videos.
Multihull vessel has good performance in waves
2 questions:
* Would X-bows better keep both hulls in the water on larger vessels? (I’m sure the leading face of the aka would have to be shaped to push greenwater beneath and to the sides).
** Do catamarans’ sterns elevate as the vessel makes sharp turns? (On a smaller scale, Ithis happens to the twin-hull Livingstons.)
Has anyone seen the new boat with gyroscope on it stops boat from rolling it’s amazing
I always feel like I'm about to watch some sort of late night B movie or obscure music video on this channel. Like, strong public access cable channel vibes. Anyone ever seen the channel on YT "Whitecastle at Midnight"?
Do smaller power cats like 30-46 feet avoid the cat slap in rough weather by powering forward and coming down on a cushion of trapped air between the hulls?
To the best of my knowledge, no. The opening on the front of the cat is too large. Even when powering forward, it doesn't compress the air cushion sufficiently. When the water rises up, the air just rushes out without offering any major cushion. You still get cat slap.
If you use wave piercing hulls with a teardrop shaped cross section that is narrow at the top, can that help mitigate roll? Or mitigate the violent roll? By the way, why is the connection between the hull and the big cross-platform rigid? I guess the forces are too big to make something like a car suspension? Or if you look at how tank wheels are sprung and damp, why can’t you have many many small little hulls behind each other on each side? I mean Ama, not hull.
Yes, the teardrop can theoretically help to mitigate roll, but not any significant amount. There was an experimental craft that did use a suspension connection between the hulls and cross deck, but I believe it was only successful on small craft.
We don't do multiple hulls like the wheels on a tank because each hull would have its own bow, which produces a LOT of the resistance for the whole hull. Ships are efficient because we get the parallel mid section virtually free of resistance.
@@DatawaveMarineSolutions Thank you for your precise and resourceful explanation.
what is the working principle of catamaran please share with me all details related to catamaran like working principle, hull form, stability, resistance , powering , material, propulsion. i want this all point of catamaran so please help me its my project so i am from india chennai.
Hello, If i may peak your interest regarding this subject of a catamaran and going all out geek.
Would a battleship or a battlecruiser be capable? Lets say the peak era, of between ww1 and ww2
Using 15 inch main gun turrets, triple or double barrels and be constructed with modern day knowledge and science.
If a monohull of that era was like 40-60k tons, what would a catamaran or trimaran be like? Would it be 80-100k?! Meaning adding 2 of the same ship and bridging them? Remember it needs to be armoured and capable of taking the gigantic turrets.
What would be the handling of a multihull versus the monohull battleship?
A video on this subject would be amazing to delve into the fantasy world of what if you were to time travel and be able to decide building one of these in 1940 and fight the germans ?!
The problem with cats is the centre between hulls gets hull slap in heavier weather and can punture or bend of not fully reinfored, this also causes heavy vibration. Checkout the american naval trimarans
they can get slapped when no in heavy wether, all that needs to happen is to surf down a wave a bit too much and the bow waves collide and slap the center
Can you make full speed U turn with catamaran?
I think for the Catamaran to be safe on leaning one Hull should be able to carry the whole vessel without sinking
that's also when they are the most fun
Guys... Does anybody know if seakeepers are good to be installed in sail cats? Is it common to install seakeepers in sail cats?
I mean; I wonder if the cat performance could be affected.
My concern is that the cat design was made to use wind loads to perform to a specific level so I wonder if adding a seakeeper for stabilization purposes could somehow affect performance negatively. Any idea there?
I never been a cat man but I'm going to see a fishing cat that's new and get it altered so I get living space without laying in a coffin hull
'Looking London . . . . . Talking Tokyo' 👀
The secret: get a naval architect. Like meee! :D
I'd love to build me a solar powered catamaran "yacht" houseboat. It seems possible and solar panels have become really very cheap.
EDIT on year later: For got to say thank you for the great videos! This was really educational for me 1 year ago. It's also surprising to see how many negative comments you get. Your videos are really great to get an overview. The complex stuff you want to learn from written texts anyways.
You read my mind. I bought a 50' sailing catamaran a year ago. Short term plan - refit it for sailing + add 5kW solar and travel around. Long term plan - lose the sails and turn her into a power cat. Around 12kW solar, 2 darrius style wind turbines, and either batteries or H2 storage + fuel cell - or both. Then buy or make 2 electric outboards (that's what my cat needs) and it's done, other than a 12-15kW diesel genset for back-up/emergency. I could maybe do the 'loop' for free, although slowly. Check out energy observer, I just saw this video today - but it's close to my plan.
@@michaelyount3843 Oh wow awesome. I hadn't seen your comment until now. How did your project progress?
I'd love to know how you plan to place the solar panel and if you plan to make one big roof. It's hard to fit enough solar on a boat under 50'.
Is there any video or a thread on your project somewhere?
I hit a few snags but I'm still planning to do this. My plan is to be able to live comfortably with lots of power and travel slowly but for free. I'm currently learning and evaluating different design possibilities. From catamaran to powered proa to hydrofoiling and trimaran. One thing is sure, it has to be light.
In the future a kite sail high in the air might also be a way to add propulsion power once you have automatic steering mechanisms and it can also be used for power generation that is more lightweight and cheaper than wind turbines.
Is there a way to make an ice breaker with a cat design? Or is ice breaking a thing for mono hulls only?
There are no physics that stop us from making a catamaran icebreaker. But mono hulls are traditionally better suited. An ice breaker needs a lot of weight, which it uses to ride up on top of the ice and break it. When you talk large weight, monohulls are typically the better choice. That said, I did see a concept design for a trimaran icebreaker. Check that out here:
th-cam.com/video/FjRSgUm03tk/w-d-xo.html
Cat sailing craft, however, are another matter: They have two stable states.
Very true, but there are plenty of monohulls that sit comfortably upside down once rolled also.
In my mind, once a boat is upside down, it's time to pack the lifeboat, I don't care what kind of boat it is.
I've seen what happens when a monohull is rolled, it wasn't pretty. Having 2 ft of sea water dropping on cushions, food, and bedding after dumping the contents of all your cabinets, and storage all over the cabin,... That boat is pretty much wrecked.
He's so cute.
Yes they are ! Up to the already mentioned´s ... But yet I keep on wondering where the 1950 ish fantastic high speed at high seas Hydrofoils went. I dont see any of them around. h-Why ...?! I fantasize the stability of a catamaran combined with 4 point lift would be rapid wonders of angry seas.
Has anyone tried canting amas?
I think the catamaran was a good design i had work in the merchant ship for 6 yrd so i believed what you said
the SUNREEF 80' CABON CAT starts about $8.2 MILLION. I was surprised how expensive they can be.
But look at the Sq footage which likely compares to a 110-120 ft monohull
I am thinking of building a James Wharram design Catamaran in Aluminum because Aluminum is faster , stronger than most Materials used for Boats , no sanding, glue, fiberglass wood to rot no painting is necessary. Building out of Marine plywood wood and Fiberglass is almost double the work and close in price and best of all a hell of a lot less Maintenance and aluminum welding as improved so much and is so much more easy .
It seems you have no experience of boat building. Not a good idea of using alu on old fashion design not thought for alu. The weights will become exponential. Add to the weight of the bare metal hull the weight, work and price of the insulation, mandatory on a metallic hull. You'll be very disappointed.
Oops, missed one item on the minus side... high stability inverted.
Excellent point. I tend to focus on the large commercial cats. If they invert, it just became a salvage operation. But for small recreational cats, perfectly normal to invert and then try to flip it back upright.
Michie TN unfortunately you're right, and Hard to right!
LoL. Hard to right = "salvage operation"
In France, with our long experience of oceanic sailing multis, we have a proverb that says while multis can float inverted and keep you alive, monhulls will always sink upright. (that's for sailing yachts).
In monohull ships a big heel angle is a salvage operation, and beyond a certain angle is a sinking. A capsized motor yacht or trawler monohull will sink in minutes, or at best stay inverted with no refuge for the crew as I have seen while rescuing once fishermen in the sea of Iroise.
Actually, that is a definite plus. A monohull (yacht) that loses its keel and rigging and does not sink is going to be a really really big washing machine, roll roll
Of course, most monohulls that lose their keel actually sink. Great stability sitting on the ocean floor.
Rolling problems. From the smallest to the tiniest. Turn Turtle. Still, I would take my chance with the cat.
what about the TRI CATS?
I emailed Nick about this he says they're experimental
sounds like an oxymoron
THEY ARE PIGS AS SAIL BOATS, FAST IF LIGHT, BUT ONLY IN A SMALL AREA OF WIND ANGLE
Thank you, Polynesians!
Information please. "Get a naval architect" is as annoying as "call now, have your credit card ready!" 😉
以前人们认为宽度大，恢复力更大，乘客不舒服，但实际是错的。当宽度越大，实际上越舒适，500吨的双体船相当于10000吨的单体船。
pitching is another issue catamarans have because of the shorter length.
Excellent point. In fact, we sometimes need to check catamaran stability in the longitudinal direction because of their shorter length. The pitching problem is also why commercial catamarans usually keep themselves 1.5-3.0x longer than their beam. That length to beam ratio avoids the entire pitching problem.
O when I found out sailing speeds up to 20 Knots is possible in a Cat I am sold rather than some big old slow Barge that sways like a tree in the wind , I loved sailing Dinghies then I sailed in big winds and a big boat I did not enjoy sailing any more I think a Cat may be my answer .
@0:55 you claim that the hulls of a catamaran are called "demi-hulls" or "amas". In my 4 decades of sailing, I've never heard either of those terms. I've only ever heard them referred to as "hulls", with catamarans & trimarans referred to as "multi-hull" and traditional sailboats as "monohull".
AMA is the Hawaiian word for outrigger hull.
Is this 2008 ?
put the teleprompter next to the camera
What of trimarans?
See my other video on trimarans: th-cam.com/video/FjRSgUm03tk/w-d-xo.html
What about trimarans?
I did a separate video about them: th-cam.com/video/FjRSgUm03tk/w-d-xo.html
Well well , So interesting I fell asleep !!
Cats are good for tenders, less resistance, good stability and all the disadvantages don't matter.
Yeah, cats are stable. So stable that they can float upside down as well as right side up. In other words, you may have good initial stability, but may have horrible reserve stability. Monohulls can be made self-righting, multihulls never.
How about a cat canoe?
Trimarans?
Monohulls, catamarans, & trimarans will be a thing of the past. SWATH boats are the most stable boats in rough waters, the high the platform is iff the water the better especially in rough huge seas.
those things are monstrosities
There not always great, there are small ones to.
They are great on anchor on a quiet day and that’s about it
So a catamaran would not be good for a hull design for ships like break bulk ship , container ship, Reefer ships, vehicle carrier ships or dry bulk ships, shame the catamaran is limited to small marine industry segments, because catamaran design does an would promote greater cargo capacities! Umm would a catamaran design be good for a Livestock carrier ship & Semisubmersible transport ship other than gas carriers an passenger ships.
Actually, the Reefer ship and vehicle carrier are both cases where the catamaran might offer major advantages. For example, vehicle carriers really fight against wind to maintain stability, due to their high sides. We have recorded cases where vehicle carriers capsized in high wings, losing all the cargo inside. The catamaran has much higher initial stability and could offer much better safety against those winds.
You did correctly identify that all those high deadweight cargoes typically go on monohulls. But I also think there are grey zones, like vehicle carriers. We may find serious innovations just by breaking from tradition.
I would definitely try a catamaran for a livestock carrier. Anything where we have passengers (human or animal) is typically a low density cargo. This is because of all the air around the livestock. Think about all that air space over their heads on each deck. Air essentially weighs nothing. That greatly reduces the density.
On the other hand, I would not use a catamaran for a semisubmersible transport ship, for two reasons. First is the draft. On a catamaran, we need clear space between the cross deck and waterline. That means the semisubmersible must sink MUCH further down to submerge its working deck. It becomes difficult to find harbors with sufficient depth for that. The second reason is the roll period. As others pointed out, catamarans have a faster roll period. One of the most frequent cargoes on a semisubmersible is a jackup drilling rig, which has truss-legs that stick hundreds of feet into the air. If the ship has too fast of a roll period, those legs will whip back and forth until they break. This is why semisubmsersible companies focus much of their engineering on predicting ship roll motions. You need a very slow roll period for a semi-sub.
@@DatawaveMarineSolutions Thank you for your swift reply and detailed information!
I believe catamaran & Trimaran designs promise robust and flexible solutions to the shipping industry well into the future, the advanced monohull designs, im sure will have a bright future aswell! Though I must admit some newer monohull designs are getting quite intrepidly LARGE lately , can the canals & ports world wide keep up with the fast paced evolution of the monohull!🤔😉😁
@@DatawaveMarineSolutions some LNG & Oil Tanker, dry bulk carrier's, Container Carrier's & Passenger ships are getting intrepidly large quite quickly, will there ever be a reasonable & economically sustainable limit to the monohull design!😊🤔 With passenger Cruise ships & Liners, its gotten to the point were there are literally self powered floating cities out there on the Oceans now day's.
@@Blime2913 I hear you about the large sizes. All the major ports and canals are currently renovating to increase their size and depth of their channels. That will happen for years into the future. Great news if you are in the dredging industry.
As far as size, I don't see ships getting much larger in the future. I think 1300 ft / 400 m is near our max. At this size, the longitudinal bending of the ship becomes a major concern. It gets so large that we actually need to consider the flexibility of the ship in waves! There are many structural issues that we typically don't worry about at the smaller scale: they become an issue at big scale. That all adds to much more complicated engineering and higher risks for daily operations. Plus, we run into construction problems for these large ships. Imagine a 400 m long ship. That means somewhere in the world, we need a 410 m long drydock to maintenance the ship! For example, the Maersk Triple, one of the largest container ships, only has 2-3 shipyards in the world where it can dock. You can expect those shipyards charge a premium for the privilege, because they have limited competition.
In the distant future, ships might get bigger. But we will need to completely re-imagine the ship structure before that happens. We will need something more flexible. Rather than a rigid steel hull, imagine something more like a floating matt of seaweed. Something that contour matches with the ocean waves.
literally no one calls them ama or demi hull XD
definitely more of a trimaran or proa thing to say ama
If catamarans and wonderful does that mean trimarans are super wonderful?
You must stop looking at the script. Everything is there.
Well, if Cats are great, then Trimarans must be awesome.
Nerd! 😹
Do you talk like this all the time?
No. I try to add a little drama to keep the videos interesting. I don't think engineers need to be that classic image the stuffy inarticulate lecturer. Though I admit I overdid the drama in some of my early videos. I continue to refine the balance between science and entertainment in these videos.
Lots of space for "low density cargo"....?? What, for my styrofoam and helium balloon collections..??!!! Overload a cat and it becomes a water pig and no faster than a monohull...