Propeller Killer? High Efficiency Paddle Vs. Propeller
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The paddle needs to be more hydrodynamic, like a duck foot
One word- Yuloh.
You might benefit from "Nighthawkinlight"'s recent video about how to experiment with multiple variables at once to decrease the number of required tests
Just ordered Factor for my parents using your code!
@rctestflight One thing that would be cool to test is to have multiple paddles that go around like a tank tread that goes around over the top of the boat then into the water
You should try a paddle that tightly hugs the hulls, almost like a ducted fan. The efficiency on that that would be interesting.
A ducted paddlewheel sounds like an interesting proposal.
I'm not an engineer but I agree. Energy is lost when water moves sideways around the paddle.
Came here to say this, it seems you beat me to it.
Yup, all I could think about aswell :)
Maybe a conveyor belt of paddles so they really get some good time pushing the water before coming out.
@chrislivengood7350 Ditto!
two ideas come to mind:
- use the rudder (extra long) as a drive like fish movements
- use sails
Sculling
Why not use a MHD?
Would be interesting to see sails, kites and rotor sails (magnus effect) on these craft. Although I do wonder about efficiency and the scale of the craft.
Also, rudder that is not lower than the floating platforms.
Tank track with pattle attached so that the pattle stays in the water all the way down the hull?
I love your videos.
I love your videos.
I love your videos.
He's not the best at anticipating problems though is he.
Time for a Destin / Daniel crossover video!
@@CockatooDudethat's how a lot of engineering is
Have you considered moving the air props closer to the middle of the hull to minimise them hitting the water? It would move them closer to the pivot point and reduce the amount of up/down swing.
Also try a ducted prop or one with Q-tips (see aircraft props for examples.)
15:26
not the same thing @@Phoen1x883
Wouldn't it start to push the bow down more as you get closer to the centre though? creating more drag and reducing efficiency as it tries to rotate around the pivot point rather than push forwards
@@Phoen1x883 The comment suggested moving them forward. The 15:26 suggested moving them up.
Check the tide tables - a slight breeze and an opposing tide can set up a nasty chop on the Salish Sea. Also, paddle efficiency tip - once the paddle passes vertical, you are pulling the bow down. To reduce that effect, offset the tip of the blade 15-20 degrees forward relative to the shaft. (almost every marathon racing canoe paddle and most SUP paddles are set this way)
yep thats how we learned to paddle. its a hawaiian thing.
@@pezpengy9308 Watermen know!
Isn't that a response to the limitations of the human "mechanism" though? The paddle blade should ideally remain vertical throughout the stroke. The most advanced paddle steamers had a linkage inside the wheel which kept the paddle blades vertical.
I think the answer is a guarded 'yes'. The optimal stroke for a paddle would indeed be to put the blade in vertically, and hold it vertically throughout the stroke. With a circular motion (paddlewheel), this is very difficult without a fairly complex mechanism (cams, followers, crankshafts, etc).
Paddle kinematics have been subject to more than a few PhD dissertations, but here are a couple of thoughts:
1. You are trying to insert the paddle quickly and vertically and remove the same way - without cavitating or pushing the boat downward
2. You are pulling the boat past the paddle, not the paddle past the boat.
3. Air time is slow time. The only time the blade is working is when it is in the water.
4. A clean blade with no nicks or thick edges will cause less cavitation.
Rather than me trying to explain it, here's Jimmy Terrell - former USA Olympian and founder of Quickblade breaking down SUP strokes. th-cam.com/video/e3uxyS-art8/w-d-xo.htmlsi=7W6IAyFTHYov2x6N
@RCTestFlight - I've got a broken marathon paddle with a perfectly good blade and partial shaft I'll be happy to donate to the cause. DM me if interested.
@mnswamp
You are spot on with your recommendation to check the tides. Just from the man’s description, it sounds like there is an opposing wind from the tides. In this scenario a very light breeze can form a pretty good chop.
Your response to:
„Ohh and its remote controlled“ killed me completely! 😂😂
Absolutely love that quirky paddle mechanism - I'd love to see that do the mission. Even if it's not as efficient as the air propellers it seems like it'll be a lot more reliable.
Also it’d be cool to see dual paddles to get differential steering or quad paddles to nearly always have propulsion
Yeah I feel like the air props lose efficiency as soon as it has to drive into the wind lol.
@@powellfilmmaking If you can combine paddles and air props and can have one drive the other you can get free power from the speed of the wind relative to the water though. A tacking sailboat would likely still be more efficient however
Just commenting to say that I agree. Would love to see the paddle mechanism have a go!
Keep iterating the paddle stuff. It's suave
Oars is a great propulsion option. And not so outside reason. It is reminiscent of a the Adventure Galley, Captain Kidd’s hybrid ship that combined square rigged sails with oars to give her manoeuvrability in both windy and calm conditions. It gave her advantage when enemy ships were dead in the water.
Oars also mimick human swimming, as I was taught: arms into the water ahead of the body perpendicular to the surface, arms push straight back, and then out of the water and begin the cycle. Very efficient
Before watching the whole video, the efficiency seems like it would be low with the single paddle. Half of the cycle time there is no propulsion at all while the paddle is out of the water. Adding a second paddle on the opposite part of the cycle seems like it would drastically improve the efficiency in my simple brain. That’s why props are efficient is because there is no wasted motion. All movement is providing thrust.
Also, a flat paddle is pretty inefficient. Designing a more efficient paddle shape would help to even the playing field a bit more.
Just watched the video, interesting the props were the lowest. You compared the surface area of the paddle and the water props and said that explained the difference in the efficiency of them, but you then glossed over the same issue with comparison of the air props vs the water props. With a larger and better designed water prop, I can’t imagine them being less efficient than the air props. Am I missing something?
The paddle uses basically no energy while moving through the air, so it doesn’t reduce efficiency. There’s no “wasted energy”
Maybe invent some kind of paddeled wheel?
@@sam-rs8wgthat’s just not the case at all! It certainly is using less energy on the top part of the cycle with the paddle out of the water, but it is definitely using a measurable amount to lift the paddle and overcome any aerodynamic drag to push the paddle forward. Throw in a headwind and the aerodynamic drag would also increase on the paddle.
Try hopping on one foot forward, then try walking forward with both feet. I bet you’ll notice some differences in power consumption between them.
@@sam-rs8wgyes there is. Motors drop in efficiency if you force them to apply high torque/speed and when you force them to fluctuate by large amounts in torque/speed. You also encounter a large amount of air resistance when you move what is effectively a huge sail in the opposite direction of boat travel.
With a paddle, there isn't much you can do about the air resistance problem short of making the paddle non static which is a challenge that we saw in this video. You can however do something about the motor efficiency by doing something like using a flywheel to even out power draw or multiple paddles at lower power so you don't have half of every rotation exclusively generating drag.
Boat designers have long since fixed these issues by using paddle wheels instead of singular paddles
I would like to see you try the paddle again with another catamaran design. If the dimensions of the paddle are as close as possible to the distance between the port and the starboard hull very little water can escape around the edge of the paddle increasing efficiency. Alternatively putting a single big paddle wheel in the middle of a catamaran would also be an interesting idea.
Just a thought, but instead of moving them mid hull as many have suggested… maybe move them up front with props angles slightly downward. This does 3 things,
1: it pulls the front end up slightly, countering it’s own weight, thereby reducing drag.
2: Air pushes partially against the water itself, which may help it to gain a little speed.
3: Makes steering even more efficient, slightly increasing the overall efficiency of the vessel over the duration of the mission, due to less energy being required to execute each turn.
I hope you try this, I’m sure it’ll be much better.
I can only see that being worse.
1 You don't want to counter weight directly by expending power. You want all of your thrust to be opposite to the direction you are trying to move. If anything, you want a slight downward angle so that the props are perpendicular to the water level even when the hull friction causes the boat to tilt upwards. This would make the craft optimized for one specific speed though unless you make the props adjust their amount of downward tilt as the boat speeds up.
2 Speeding the water up and slowing the air down will increase the propellers efficiency but also increase drag on the hull. But even if you do move the hull and props far enough from each other, this won't counteract the negative effect of 1.
3 How does this do anything specific for steering efficiency? If anything, I see it creating an asymmetry in hull drag that counters the way you are trying to turn.
I'd also like to see more paddle development. There are some tips from the cycling world you could try, like taking mass out of it, as well as an elliptical gear that puts a more constant amount of force on the motor throughout its path. And I second the folks that mentioned tip recurve for less drag, and that more width might also have an efficiency boost (if you can control the flex)
By recurve do you mean bended tips on the vertical sides of the paddle (English is not my mother tongue) ?
I really want to see the long mission with the paddle. From the short test you did, it looked quite promising
Yup, and it definitely would't mind getting wet. The only question is: if the waves are high will it travel forward high enough to not cause a drag.
I recently had the pleasure of taking a river cruise on an old paddle steamer that had been converted to diesel. It was equipped with feathered paddle wheels so it would be more efficient.
Very interesting challenge. I guess a fish inspired propeller that that creates a wavy motion would have both very high efficiency and anti clogging properties
Exactly what I came to comment about. Nature developed tail fins! Why aren't we replicating that?
@@seanhoude because it's not a circular motion.
Circular motion is very efficient and easy to replicate and generate, especially with electric motors.
Yet any living creature can't create circular motion because flesh can't create ball bearings.
As seen even in this video, converting circular motion into reciprocating motion comes with transmission losses.
That's what prevented tail fin "propeller" to become economically viable.
@@Shishou_Shi Historically, we have created linear motion and turned that into circular motion (with losses). Why not use pistons to drive tails or wings instead?
@@seanhoude because it's very inefficient.
Yes piston engines are inefficient.
That's another factor on why electric motors are getting so popular again.
A fin tail prop is perfectly doable, it just doesn't make sense to do it.
Not to mention that it's low power, whales might create enough power to move a boat, but most fish put out very little energy, relying on small scale efficiency being slimy skin and scales with a tiny frontal area.
None of which is useful for boats.
@@Shishou_Shi I suspect all of those things could be very useful for boat and especially submarine. Many fish, even large ones like tuna and shark, travel very quickly, with great power, all very efficiently. Whale are a prime example of how this could be scaled upward.
That human-powered hydrofoil boat with the big propeller was a project that my Dad worked on while he was a student at MIT! Still hasn't been beat after 30 years!
If you design your rudders with a tapered skeg directly in front of the rudder's leading edge, you'll get better steering authority, better straight-line tracking, and the weeds will just slip right off. Then you can mount your propellers farther forward and maybe keep them out of the water a bit better?
Do you think mounting the props on the centerline would make any difference? I feel like the front and the back go up and down a lot with the waves but the center kinda stays the same.
I canoe and I suggest that you take a lesson from marathon canoeing. A classic straight-shaft paddle is inefficient because the paddle is pushing down in the first third of the stroke and lifting water in the last third. It is only efficient in forward motion in the middle third where the blade is vertical. Efficient modern paddles are called "bent-shaft paddle". google it to see what I mean. I think with a bent shaft you will see less bobbing up and down. In your video you can see the big paddle lifting the water at the end of the stroke.
A bent shaft with a smaller blade but a higher stroke rate would have several advantages. A smaller blade with have less air resistance in recovery. Love your videos. Thanks for sharing your journey
That's very interesting, I'm going to look into it.
Is there a video on optimal paddling techniques you can recommend?
It would be cool to see a linkage modeled after a real canoeist stroke as well, and with some feedback control so it can adjust to different speeds. +1 for the bent shaft paddle, they definitely feel more efficient in my experience.
This is why I love youtube, for the creators actually creating things and exploring the world around them. There are still efficiency gains to be had on the paddle I feel. As it tilts and pulls out it's lifting the water rather than pushing. If you look at rowers they have a really efficient paddle stroke (as efficient as a human can make them). they put in vertically and pull out vertically. I doubt it would make anywhere near enough difference to beat the out of water prop though.
Props to the lady giving you footage, that you actually used in the video!
Props, hehe
Another propulsion technology you may want to look into is something some pedal powered kayaks have, which are two fins/wings that swing back and forth in alternating semicircular paths to propel kind of like how penguins swin
Hobie Mirage drive? Seems very seaweed prone
Google dolprop!
Sometimes it's one vertical fin.
@@rctestflight I'm curious about the efficiency on the mirage drives. I think it's less than a propeller but is has the added benefit of folding up to the hull in shallow water, being retractable, and easy to add two propulsion units. You also get to use your legs which have more power than a kakak paddle with your arms. More moving parts then a prop and doesn't solve weed problem as you noted.
The feathering paddle wheel was patented in 1841.
It does what you are trying to do, make a paddle wheel more efficient by keeping each blade perpendicular to the water. It uses a rather simple mechanical linkage on the wheel to accomplish this.
Example, many videos of SS Waverley, a very fast sidewheel steamboat.
Both my mother and mother in law traveled on fast paddle wheel steamboats with feathering paddles.
on that paddle - you could probably reduce it's weight substantially by pocketing out the front side (depending on how fast you're going...) some but leave a waffle supporting set of ribs for stiffness - and on the area where it's mounted there's some excess material there - might be able to pull some crescent shapes from the next out to the sides... great video - love seeing guys experiment with things.
2It would be interesting to see if an "optimized" paddle shape was significantly more efficient than just a flat one. Curves, scoops to direct water inward, upward, downward, or outward, ducting, angle of attack, etc. Paddles for racing shells are usually slightly curved with interesting shapes to them.
That's what I thought, maybe stop water spilling off the paddle by having curved ends.
Paddle "plan form" matters as well. High aspect ratio blades feel more efficient (might be subjective) but are less effective for acceleration (so actually transmit less power?) and inferior in shallow water. Many canoeists carry more than one type of paddle and use them like switching gears on a bicycle.
Interesting. I suppose, were curved paddles more efficient, it would have been discovered by now. Seeing a paddle steamer tossing up lots of water looks a waste of energy. @@highloughsdrifter1629
rather than moving the propellers up just move them forward, keeping the weight closer to the centre (for and aft) will reduce hobby horsing, there's a reason many catamarans put their outboards close to the centre, it prevents cavitation from hobby horsing.
Also maybe look into using a youloh for a paddle (similar to a sculling oar), your paddle mechanism turned 90° would be perfect for the side to side motion and you only need to rotate the youloh oar to control forward or reverse, one on each hull still gives you deferential steering
Two possible ideas.
I know you said you made the paddle as wide as possible, but it really seems that there are a few inches on each side of the paddle left.
Second, high end canoe and kayak paddles are made with a buoyant material to lessen the amount of force needed to pull it back up from the water. Making the paddle thinner and lighter would be great as well, and I’m sure a higher quality/more hydrophobic coating will help.
I love how you do your prototypes. Just slap everything together and get it working. No worries about if it tipped over or anything, lol. I wish I had that attitude I could get more done, not worrying about making everything look perfect or trying to account for any predicted failure.
Hi,
if you reduce the distance between the paddle and the hull, you may be able to achieve even greater efficiency.
Nice video as always! Have you ever heard of the Voith-Schneider-Propeller? Its not the most efficient propulsion system (based on a cyclorotor) but highly maneuverable and definitly a unique design. Would probably be a great fun video!
Very cool, had never heard of this, tnx!
Someone on youtube made a long horizontal one as a means of lift and propulsion for an aircraft. Tricky getting it to work, but it could hover as well as manoeuvre.
Hey Partner - I was walking around Seward Park about 2-3 years ago when I got a semi-novel idea for a watercraft propulsion system that I think you might be able to realize:
You know the "organic airship" design in Studio Ghibli's "Howls' Moving Castle"... with those weird 'wings' popping out of the airship recurrently to provide thrust?
So... basically that, but for water. The essence of this idea is to mechanically produce a semi- (or later, fully-)parallel-to-water-surface rowing motion:
This simplest version wouldn't be very Ghibli-like at all - just a mechanical row-boat, in essence:
1. Minimum two 'oars' in water, one each side of the boat.
2. Both oars would be connected to a gearbox via direct drive, which would manipulate them such that the tips move in a vaguely triangular shape: One side of the triangle would be the extension into the water, one side would be the thrust stroke, and the other side would be the retraction from the water in preparation to repeat.
3. In this simplest version, i believe the geometry would work out such that if the oar handles were above the waterline, angled into the water, this triangular path would necessarily remove them from the water in the retraction stroke, eliminating the drag that would otherwise obviate this idea.
>> I can sense that steering could be gracefully accomplished by some kind or gear-box which would donate additional speed to one side if the other has brakes applies to it (a basic differential would accomplish this), but that would increase complexity. This could be done electronically if either side were driven be their own motor
Given that a two-oar system may probably be pretty janky in its movements...
1. The next-most complex version of this would be the addition of two more oars....
2. ...or ADDITIONAL oars to make a Crew / Caterpillar version. Like analysis of an animal's gait, research would have to be done to tune in the best timings for each oar to fire.
However, my FAVORITE version is the following:
1. Take the entire system you develop above, and put it **under the waterline**, and parallel to the water's surface (i.e. no angle needed anymore).
2. Then, adjust the shape of the oars such that they fit in a custom rubber / silicone sleeve. This would provide a larger thrust surface, and seal the oar's interface to the hull without the usual friction of tight axle seals.
>> The oar-travel geometry will need optimization, but what you'd essentially get at this point is a bunch of "fins" which scoop through the water, penetrating it at travel-speed, scooping the water backwards to generate thrust, and then retreating within its housing in the hull to repeat the stroke again... like a frog or human swimming through water.
>> Naturally, there would be absolutely no way for this system to gather seaweed.
The seals and the geometry feel like the most complex parts... beside that, I can't see any serious flaws in this design.
Have you heard of the experiment the British Navy conducted in 1845?
They built two virtually identical ships with the same displacement, engine size, and hull geometry. HMS Rattler had a screw prop, and HMS Alecto had paddle wheels. They tied the boats together stern to stern and had a tug-o-war battle. The screw prop won the battle.
You could do a similar experiment!
Interesting. The Rattler crew was probably buying many drinks for the Alecto crew the night before! Essentially a bollard or static test which is quite different than underway conditions.
I think you could squeeze some more out of the paddle idea. Your first attempt went pretty well, compared to the highly engineered air propellers. I'm thinking two paddle linkages mounted on the a centrally located drive gear 180 degrees apart, with the vertical shafts on the outside of this assembly right up next to the hulls. Each paddle and shaft would have to be L shaped like a flag, so they could pass one another. The circumference of the drive wheel might have to increase too (bigger gear is probably better for the forces at the teeth anyway). Then there's the idea of curved paddles rather than flat ones. Real kayaking paddles are not flat.
Right, there are many opportunities to alter paddle design that should be explored.
"Plus one" for two paddels, otherwise half the time is spent with no power being transferred and 100% of power used to move a paddle through the air.
I'm thinking two symetrical linkages mounted 180° apart too with the same paddle area but halved.
I liked the paddle the most. Please take that for a long cruise.
haha yeah that was awesome.
Next hull option: trimaran. Carry 90-95% of hull displacement in the main hull, at length to beam ratio of about 14. The longer hull should reduce the pitching problem at this small scale, ideally you’d have -6ft length or so. Single air prop near center, center of effort slightly forward of center of drag for directional stability. Steering by side hull yaw if you could do it, to eliminate the need for a rudder. Side hulls should be toward the stern, gap from side hull to main hull should be about the width of the main hull beam. Would love to see what you could do with that!
Some ideas:
-Sails. (Sorry couldn't resist it)
-Scullying oar. This is an ancient propulsion technique where you use a single oar from the stern of the boat, wich is moved from side to side with a special technique.
Modern engineers and amaterur tinkerers have developed this concept quite a bit, and modern scullying oars are surprisingly effective.
When I see the dual paddle mechanism, it reminds me of how ducks and other swimming birds paddle with their feet.
The big difference is that they fold their toes on the forestroke, to reduce drag, then they spread their toes again on the backstroke.
There was a model of scuba diving fins developed by Mares, that tried to mimic this. They were sold back in the early 00's if I remember right.
Extreme free-divers otherwise tend to use very long and floppy fins, apparantly those are the most effective for the human body.
For human-powered crafts, rowing with oars is far more effective than using a paddle, and the double-sided kayak paddle is way more effective than the one-sided canoe paddle.
I think the key is getting as long a stroke as possible. The effort you spend with the oar or paddle out of the water is minimized by having it counter-weighed. An oar is balanced so that if you let go of it, the blade will sink just enough to where it dips in the water and floats there. You don't need to use much energy to lift it out of the water. The double-sided kayak paddle is held so that it balances in between your hands. But again, these are techniques based on the human physiology. Muscles and bio-mechanics are not as effective as rotary motion, or we would have running cars.
When you steer a boat, you either utilize the hull speed, and the rudder will create a difference in pressure by altering the waterflow around the hull.
With a propeller craft, you can use a much smaller, and simpler rudder, because you are only re-directing the waterflow from the propeller. Single-hull, displacement-crafts have the rudder as an extension of the hull, so they won't catch seaweed.
Catamarans and dingy's are non-displacement hulls, (ride on top of the water) and they need to extend the rudder down below the hull, so they will inevitably catch weeds. I don't see a way around it with a traditional rudder design.
A longer hull is more course-stable, and you need to excert less energy to make course-corrections.
Just looking at your prototype boat, I think it struggles in the waves because it is too short, too top-heavy😢 and it is a bucket-shaped catamaran. It's deplacement isn't very progressive, so the pitching makes it dive in each wave. If your hulls had been more V-shaped, they would carry over the waves instead of dipping into them.
Another propulsion type that would be cool to explore is a bellows based water jet.
I have no idea of how to build it, but maybe start with a gusher-type bilge pump.
When in 10 years or so every large ship is running paddles instead of propellers. We know who to blame. 😁👍 Merry Christmas and a happy new year. 🎅🎆
Do you take into consideration the weight changes, and the center of gravity? Both could influence the drag significantly.
@rctestflight If you really want an energy-efficient ride by a watercraft, there are two possibilities: a) Nullification of water-drag and water-friction by using _supercavitation_ (pyhsical details see Wikipedia). Technology is simple and already used on big transport ships: Realease compressed air through a grid of holes in the part of the hull below the waterline. This works even for submarines and torpedoes (look up the the term «Shkval» and take a look at the achievable speeds). The second proposition sounds a bit outlandish at the first glance, but is even more effective, since water- and gas-resistance is completely taken out of the equation. It is gravitoelectromagnetism (GEM). The US-DOD uses this propulsion method since July 2011 (end of the STS-programme) in their TAV (trans-atmospheric vehicles) and AMV (all media vehicles, that can operate within the atmosphere, under water and in deep space; volgo USO). The physics behind this propulsion system is sound, the technology is simple and reliable.
Thanks Lady! I think that just proves that you have built a very interesting machine. I'm always amazed by your clever ideas and solutions.
Paddle with closer tolerance between the paddle and the hulls. Propellers mount them further forward, say 3/4 aft. Love your projects.
yeet the beet so it beet to the yeet
Great video. Just some notes: (please correct me if I'm wrong) I believe to accurately measure the efficiency of the propulsion methods the speed of the boat must be constant over the different tests to exclude the effect friction has on the efficiency. The faster you go the more energy you waste. So an inefficient method might seem more efficient if it travels at a slow speed compared to a more efficient method going at a higher speed. The effect of different speeds on efficiency can be dramatic as, if I remember correctly, the drag force increases quadratically with velocity. The best way to measure the efficiency will be in a lab setting where factors such as wind, water friction and waves etc can be eliminated. An example of a lab setup would be rigging your propulsion system to a load cell in a bath, controlling it to push against the load cell at a fixed force, running it of a fixed time and the measuring the amount of power it consumed to push lets say 200 grams of force for 10 minutes or something similar. This method still is not accurate as the efficiency of a propeller increases as the speed of the craft increases and in this setup it would be standing still. On the other hand I think that the efficiency of the paddle would decrease as the speed of the craft increases. Measuring and comparing efficiency of different system types is extremely hard as you easily run the risk of comparing an inefficient method running in an efficient way with an efficient method running in an inefficient way. To eliminate this you can try to find the most efficient operating point for each method for example taking into account prop size/paddle size, rpm, vehicle velocity etc and then comparing the most efficient case of both methods. I realise that going this deep is not the intent of your video so it is just for interest's sake.😂
Great video as always!
I think the boat is still usable .. What if you raise each mast and move them to the middle?? From the middle of the boat it would be almost impossible for the props to hit the water! Give yourself about an inch of clearance from the deck.
I think your next boat should be a larger scale autonomous sail boat! Saw the ones that now go around the ocean mapping and can stay out for a year.
I'll second the move of towers idea. Theres no reason that they need to be at the back.
Nah, I think the boat is too short and have the wrong shape. There is no way around the pitching.
Any mechanical propulsion system that uses leverage instead of a propeller, will use the hull itself as a counterlever, and any non-continuous propulsion system must rely on mometum or it will hop like a frog.
What about a corkscrew propeller?
Make the propeller blades continuous with shallow angles so there aren't any corners for sea grass to catch onto.
Edit: if you want to be fancy, you could try a golden ratio turbine.
th-cam.com/video/BxNHOMJGcj0/w-d-xo.htmlfeature=shared
That was tested by the first guy to develop the propeller. It snapping and working better broke is where the idea for a modern propeller came from.
I forget his name but his steam powered boat is now in a museum in Britain.
Racing propellers are half-submerged and maybe that's enough to throw away the seaweeds during the upper part of each revolution.
Highly enjoyable and inspiring video!
I think, there are many more parameters, that might boost efficiency: First question might be, what theoretical limit or reference might apply = some car? On the other hand, transport by ship is said to be way more efficient than trucks and trains, though, on the other hand: You don't go for payload (by now).
My ideas for the paddle solution are to
1.) try some shovel shaped paddle and additional vertical "walls" (what is called "fences" on airwings) to minimize vortices
2.) optimize the inner shapes catamaran body (maybe even like a jet propulsion-like tunnel and different intake/outbound diameters (maybe +/-25% ?))
3.) add 1 or 2 paddles diving in in an interleaved pattern over the length of the hull for steady water flow
And I'm really curious about the bionic/toroidal propellers, which are said to be twice as efficient.
the paddle wheels in our old german steam driven ships on the river Elbe in the town Dresden do constantly adjust the angle of the blades, so the keep beeing amost vertical all the time they are in the water.....with an very easy linkage system
I love your paddle design. The angles entering and leaving the water are almost perfect. Feathering the paddle parallel to the direction of travel would be most efficient on the return stroke, that is what you do with a canoe paddle. But the mechanism to do that would probably not be worth the small mechanical advantage.
The main problem with paddle wheels is that half the wheel does nothing, the front quarter tries to push the boat up and the back quarter tries to push the boat down. Only the blade at the bottom is pushing in the desired direction. But, what if you made a tank tread instead of a wheel. A larger percentage of the paddle would be pushing the boat forward and half the paddle would always be in the water instead of a regular paddle which is out of the water half the time. Just a thought.
That was solved in 1841, the "feathering paddle wheel". Look it up. It was widely used on large fast steamboats. The paddles are turned to be perpendicular to the water throughout the time that they are in the water.
Another great video. I’d be happy to watch another one with the same catamaran and the propellers up and more centered instead of on the back. I like scientific method in these videos. Thanks! 🙏🏻
Fantastic stuff - thanks. I was wondering about putting the propellers halfway along longer hulls - always clear of the water and hull length is related to max speed.
That album y'all put up comes up while I' driving. in the shuflfle and it's really a nice set of jams. Thanks for that. Sick paddle.
Very inspiring and I must ask about the paddle. Would giving it a scoop shape make a difference? It make quite a difference in a water wheel when it is a Pelton wheel.
If you look at competition paddles they are scoped, so this slight modification is clearly worth testing.
Why not doing a Pelton inspired thingy that has straight edges into to the water, not a cup.
Also using a heavier wheel storing the energy so that the motor is used more evenly in the stroke is worth checking out.
Fantastic! I would love to see you try a 'whale tail' propulsion system where the whole paddle stays underwater and pivots up and down.
Or left to right like a fish. The whale tail has a weaker stroke flapping up because there is less water and it can be lifted above the surface. whales are more efficient at depth. but fish stroke is less variable near the surface.
All the evolved natural propellant techniques are worth looking at like squid squirt or the cuttlefish rippling skirt. which is great efficiency at low speed and very controllable like a tank track. th-cam.com/video/GDwOi7HpHtQ/w-d-xo.html
Love the test, fail, test, fail, test, success! This is so cool to watch the constant striving for efficiency. Thanks for sharing!
The flipper-style 'mirage' drive some kayaks use would probably cut down on weeds with added speed. it's a pair of side to side paddling flippers that are opposed, to mostly balance out the lateral movement.
I had a couple of Hobie Mirage Drive kayaks and that drive could out-pull two regular kayak paddlers in a tug of war.
Being that airprops have the highest efficiency rating so far: Perhaps having them mounted closer to center for whatever boat you do next would help.
Also, there's another comment that mention caterpillar track paddles. That would be interesting to at least see, maybe with the paddles in a crescent shape too.
You can get more efficiency by mounting the propellers more to the front of the vessel. Bow waves increase in height with the speed of your vessel and cause the boat to dip at the back. This increases drag and messes up the thrust vector of the prop.
Edit:
This would probably also help with your water hitting problem.. The would be raised higher above the waterline...
Great project. You seem to have covered all the bases. My observation for what it is worth is regarding the position of the airscrews. Maybe consider, positioning the pylons at the longitudinal centre of flotation (LCF) - I feel this may reduce the effect of the thrust on the hull which at the current location (aft) may be inducing longitudinal oscillations on the vessel.
PS: The LCF is at the centroid of the water plane area (at the working draught).
Cool idea! I would like to see the way-point mission’s data.
Maybe just put horizontal flat or curved hull extensions under the props so the water always stays below them. They could be above the normal water line and only touch the water when a wave comes.
I really like the idea of supersized air propellers and electric motors. On real boats they could be used to extract some power from winds, maybe enough to meaningful on recreational boats that are only used occasionally.
Maybe you should explore wave propulsion.
I think that Mabe using 2 paddles that alternate when they are in the water could help with the slowdown between strokes and making them a little more snug against the hulls
"Plus one" for 2 paddles
If you observe Olympic rowers, their oars are above water for quite a while before next stroke.
It helps synchronising of course but also reduce the amount of turbulent water the rowers are pushing around, because their boats keeps gliding in between.
Of course I don't know if the same would work with your 2 hull paddle setup... their boats are very long and narrow, which is a clear advantage in fluid dynamics (like comparing an arrow with a ball).
1) Wind direction is a more important variable in wave height as is wind speed. The longer distance the wind gets to work the bigger the wave for the same wind speed.
2) For the paddle design, try experimenting with elliptical drives to max efficiency. Also if you want to test a folding paddle design use a coordinated solenoid hinge mechanism.
3) On an unmanned vessel, it shouldn't matter where you put your propellers. I would put them amidship offset (èasier turning)from the hull to accomodate larger propellers higher off the water at the mean stable point of the boat.
your paddle boad might work on land, if it is mounted a little lower. Would be a cool amphibious vehicle.
Would be interesting to try a caterpillar track system for the paddles. Would be similar to having multiple paddles
or maybe... a water wheel xD like... in old ships xD i mean multiple paddles on wheel... simplier than what he have here... ok i checked it's called paddlewheel xD
@@bartoszcabaj8761 I think there are some inefficiencies simply using a wheel with the way the paddles enter and exit the water which is why this is such a cool method and why a continues track designed to enter and exit efficiently might be a good idea
@@stocky9218 yeah the inefficiency from the paddlewheel comes from the entry and exit angle. the paddle is more efficiant casue the pushes on the water nearly liniarly. best way would acually be something like tracks where the majority of the travel throgh the water is completle sraight. however the losses on the gearing, trackchains and rollers would be too much.
The old paddle wheel steamboats had paddles for a reason. Some in the rear and some on the side at the mid point. Perhaps a little research might help.
Unfortunately, track systems are generally a bit less efficient overall, due to the greater amount of friction they're dealing with. The tracks are pulling hard against the bearings of the inside wheels, producing increased friction. Each link turning and changing directions every loop produces friction. The paddles on top are causing air drag.
The wave issues out on the sound could be examined as a function of hull length vs. wavelength. On a different sized hull the lever action of the waves would just pass under the hull unnoticed or perhaos you could tune a short hull to cause destructive interference with the 2-knot wind speed wavelengths.
Interesting video. It reminded me of the story of Isambard Kingdom Brunel. I don't know if you have heard of him. I live in Bristol UK and he is very famous here. I think he was responsible for designing the first iron ocean-going steamship. He is known for an experiment to decide which was more efficient a paddle steamer or a propeller-driven craft so he staged a tug-of-war between the two, The propeller craft won and that is what he used for the SS Great Britain. The hulk was towed back from The Falklands and somewhat restored rests here in Bristol.
Great videos! It was super cool to see the efficiency of the fans over the paddles and props. But one thing: those aren't puffins; they're some kind of duck.
Buffleheads, I think.
@@mschmidt62 Yes Buffel heads for sure
I studied and tested a concept a while ago that basically used two rudders or flaps moving like the tail of a fish, but with their movements mirrored across the center so they would move inward or outward at the same time to not steer the boat like a single flap would. It would be interesting to see that tested again
I put a RC plane prop on an electric trolling motor and mounted it to my canoe. I trimmed the prop down some and was very impressed in how fast it moved the canoe.
I would create a waterproof sheet on the bottom half of the hulls with the same texture and aerofoils as shark skin. Idk how small of details a 3D printer can print but maybe you could research the shape of the individual shark skin foils and make some thing similar you can wrap on the bottom.
Anyways if it’s possible to get a similar scale “scale” pattern (I think they are called placoid scales) to cover the parts you want the direction of water to flow your efficiency would increase dramatically.
Nice video ! I hope one day you can test out contra-rotating props !
Coaxial props? They are less efficient
@@rctestflight Dual props that spin in opposite way on the same axis. Probably less efficient because it needs some kind of gearbox, but it would be interesting to see how they perform, at low and high speed. Some people put them on their speedboats, must be pricy so there has to be a reason for them being sold.
Yes, thats called coaxial props. Less efficient but higher peak thrust for the size @@eugenef4579
I don't think you have milked this subject dry yet. I'm wondering if a surface penetrating propellor might reduce underwater drag enough to be an efficient option. Thanks for the videos !
*Parallel Conveyor/Belt Paddles,* 1 above the other.
The paddle arm is connected to both, so the paddle is always vertical, no angle when it enters or leaves the water, or during the stroke, the paddles always pushing the water directly backwards.
The vertical distance between the 2 conveyors determines how far the paddle is inserted or lifted in/out of the water.
Longer stroke means less energy lost dropping and lifting paddle in/out of water.
*Single Conveyor/Belt with Multiple Paddles,* paddle on hinge with extended hinge pin with lever at end, use cam or similar and spring to position the paddle so it is always vertical.
As others have noted, *Widen Paddles* to be closer to hull, decreasing water lost around the edges of the paddle.
Omg! I grew up on bainbridge. I live in NC now. This is my first video of yours. I cant believe this!
I think for these longer waypoint missions with the larger props, you might just be better scaling up your hulls. More room for batteries while potentially resisting larger waves better?
At least scale the hull length as the back tipped into the water. sideways it's quite stable already. also longer hulls tend to be more efficiënt for a number of reasons so yeah i'd agree
If you added a flywheel to the motor it would even out the current spikes mechanically as well. This is awesome btw!
+1 to the flywheel idea, I think its sound especially on a boat where weight is less of an issue.
good for you!! 1% inspiration 99 perspiration!! with the resources you have, now Id like you to try tyhe efficiency of an hidrofoil moving into a sinusoidal wave pattern like the propulsion of an "aqua skiper or pogofoilor or water bird" depending who copied it, I've tried it in real dimensions and it works!! but what I think it would be the best efficiency setup would be the whale like tail propeller, no doubt, I´m into it
I like the use of herringbone gears, usually when being used in situations where liquids are involved, to reduce fluid lock, we cut a gap the center of the V.
This is what people in 1870s thought electric boats would be like
Wouldn’t it be better to mount the props in the middle of the boat (lengthwise) to a) minimise the height difference they experience when the boat is rocking front to back and b) for more effective differential thrust cause the center of rotation would be in line with the props?
my thought exactly.
If you put the props in the middle of the boat, props in the water are going to try to force the bow out of the water which reduces efficiency because you'll be breaking waves with the bottom of the hull instead of the bow. Putting an air prop in the middle will force the bow into the water which will cause it to break waves deeper into the bow, also decreasing efficiency. You avoid both of these problems by putting the props at the rear of the hull
@@user-jm8sy5ox2j good point. Didn’t think about that.
Very very cool. I do like the dual propeller design I think if you Where to lengthen your hulls to about double the length and move the propeller closer to the center of the Craft length you would get away from hitting them on the water
Sometime in the 80's or 90's I remember some F1 powerboat competitor experimenting with a very high speed paddle wheel instead of the regular propeller used on the competition boats.
I have no idea what the results were, but at least it shows that people has experimented with paddles relatively recently. I'm also uncertain if this was before surface cutting propellers were developed or not. Surface cutting propellers can be run at much higher revolution than ordinary propellers without suffering from cavitation causing performance problems or propeller damage.
I really like the paddle idea and the large high efficiency prop ideas! I'd like to see further refinement!
I love the lady who sent the video she's so enthusiastic! Anyways, I hope I'll see you around Seattle while working on these sorts of projects (I'm at UW lol)
Put the props at the longitudinal center of the hulls. You could put rudders behind the props like airboats use to alter thrust vector and steer the boat. Also, put as much weight as you can towards the center rather than the ends to help with the hobby horsing when you encounter waves.
The paddle mechanism was pretty cool.
Back when ships were transitioning from sail to steam the British had a tug of war between two near identical ships ,one was a paddle steamer the other a screw driven vessel, the result of this tug of war was a win for the screw driven ship which was able to pull the paddle steamer at 2.5 knots. This resulted in the British navy adopting screw driven ships over paddle driven due to their better efficiency. Just a thought.
Check out how the implement prop/s into the hull of the newer fishing kayaks. Basically they are recessed into the bottom of the hull. Although to repletely negate prop fowling you could also incorporate a mesh, cage as encapsulating the prop. However this ideally is flush with the bottom of the hell. Just a thought. Watch the videos they have made on these fishing kayaks. I know a fowl proof prop can be employed.
I like your videos. On this I would like to give you some of my thoughts.
1) in dragonboat racing teams are starting to rotating their paddles 90° to reduce drag on the forward stroke.
2) when comparing efficiency. There is a great influence of hull drag in regard of the achieved speed. Unfortunately I don't know what it is called in English. In German it's called "Rumpfgeschwindigkeit" that describes the effectiveness of hull length to desirable speed. It has to do with the produced wave ... Sorry I'm no pro in that area. But I suggest it could have an impact on the way you test efficiency.
3) the best solution is not always the most practical one. There is a reason why traditional Propeller underwater are so commonly widespread used. But I do like your creative approach to discover new possibilities.
Keep it up.
Awesome! Some friends and i were toying with the idea of sending an autonomous boat across the ocean (a big loop of the Pacific, passing by Hawaii). I imagine the chances of survival would be low.
As someone who spent a fair bit of time paddling on the ocean with Polynesian style outrigger canoes, one thing I noticed is that the path of your paddle stroke is pretty inefficient.
Ideally you want to put the paddle in about vertically, drag it through the water, and then raise it out vertically (perpendicular to the water) and repeat.
As it is currently your paddle is dragging your boat down at the recovery of its stroke, increasing drag on the hull.
It might be worthwhile taking a look at how (good) human paddlers move their paddle in the water, following the path of the paddle blade and then changing your linkage (you'll need something a bit more complicated) to replicate that stroke.
My solutions for weeds jamming up underwater props, is either using fans like a swampboat, or long, flowing bio-mimicry tail fins, from like a fish or whale. Swimming tail fins are also my solution for noise, if the back & forth mechanism is well sealed up & lubricated. Inside a shin maybe. It would be fun trying to mimic fast fish, like marlins/swordfish or mako-sharks.
Multiple paddles to remove the wasted part of each stroke and smooth out motion.
Caterpillar track with multiple paddles/cups to give continuous drive.
Oscillating fin that goes the length of the hull, like an eel.
Retry the air fans with them mounted at the centre of the pitch axis so they don't hit the water and give them a cowling/duct to improve efficiency.
I love everything you are doing. I am a techy as well. Great Video. Thx
You have skills man!
It's fun to watch!
In human propulsion, one of the recurring footnotes is that the Chinese yuloh oar allows someone to propel a very large boat or even a barge with tens of tons displacement at several knots for well under a hundred watts (one woman, one hand, not breathing hard). It's a similar oar motion to how animals swim using their tails. I am curious if you could replicate it in a motorized dual yuloh design for your cat.
I think the floppy paddle could be improved some, though it's hard to say if it'll actually affect efficiency. I was thinking if i didnt hinge right at the top, it might recover faster, so what if it could bend along its length (like flippers) but only one direction?
Think like a snap bracelet or a measuring tape, but hold it curved so that it can flex when needed, but doesn't rely on little elastics to recover, and instead on the flexibility of the material, and curvature that you design into the mount.
You should use a cam style shaft and have 2 paddles so one is constantly in the water. Similar to the guya bicycle set up in the canoe 🛶. But still in the center. But even if you don't. The paddle still need to be cupped or concaved like a snow shovel. You're losing thrust efficiency with water going around the outside of the paddle while it pulls the boat forward. And on the return stroke water would move smoothly off of the blade as well. You could also try thinner hinged blades around the entire diameter of the paddle (in the water) that flip back during the return stroke to eliminate drag. Just some recommendations\ideas.
I had a flying buddy who made a 100' long reproduction of a paddlewheel steamer type ship, and used it giving tourists rides on the Green River near Moab for years. He said it was amazingly efficient, suprisingly so, powered by two Detroit 3-53 diesel engines.