Rotor Sail Boat?
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- Äas pĆidĂĄn 5. 06. 2024
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I've already built a Magnus Effect Plane, so how about now I make a Magnus Effect Boat? I designed the boat on Fusion 360 CAD and then printed the parts with my Ender 3 printers.
00:00 Intro
00:40 Build
02:04 Ad
03:21 Test 1
05:55 Modifications
06:15 Test 2
08:37 Conclusion
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Keep up to date with what I'm working on: / jameswhomsley
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Project Air is all about building DIY aerospace engineering creations, learning about the science behind them and testing to the limit. Make sure to check out the rest of the channel to watch projects on RC planes, drones, rc boats, hydrofoils, hydroplanes, seaplanes, rockets and more. Project Air was started in 2017 by James Whomsley đ
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andrewapplepie.bandcamp.com/ - VÄda a technologie
What do you want to see me build next? Comment suggestions below! đđ„âïžđ„ïž
build a modified ornithopter
or build a swashplate quadcopter
it would be better to use two sails with dimples
Make IT autonome
I want you to build a V2 of this. Iâm a former sailing instructor - look up the term âweather helmâ. It will help steer you in the right direction (pun intended). Continue with the sailboat design - just model your boat after a known working setup (international A class catamaran could be a good starting point - note the location of the daggerboards). Good luck!
DIMPLES! You need dimples on the magnus surface to increase the effect. About the density of golf ball dimples.Also have it lower and more squat in shape to reduce toppling moments. It may also help matters when thrusting if you actually TILT the magnus rotor; not sure which direction but I believe it will definitely help with stability.
Dimples limit drag by creating boundary layer turbulence. Wouldn't you want more drag and thus thrust from this smooth cylinder? Seems to be what's used on large "Rotor Ships" if you look those up.
@@daveeckblad Nope, dimples add energy to the flow allowing it to 'stick' to the surface better, so in theory a dimpled magnus rotor would be able to 'hold on' to the air longer, giving it more opportunity to divert the air for the perpendicular 'thrust' force
There is less wind near the surface of the water, a squatter rotor would be slower.
If you add dimples, is it still the Magnus effect?
Show me an existing large scale rotor ship with a dimpled surface. Comaxel is a good example with lots of photos available. They're all smooth far as I can tell.
From Sci America: "Dimples on a golf ball create a thin turbulent boundary layer of air that clings to the ball's surface. This allows the smoothly flowing air to follow the ball's surface a little farther around the back side of the ball, thereby decreasing the size of the wake."
Obviously golfball spin stil imparts a magnus effect. I believe the effect is lessed by the dimples but obviously not cancelled out.
The purpose of a golfball design is to move through the air with the least amount of friction wheras a rotor design relies on as much friction as possible to create the most thrust.
Real sailboats/catamarans have big centerboards, that are simply big ass vertical fins in the center of the hull, this helps to reduce the drift caused by the wind
As well they need to be centered under the center of pressure of the "sail".
I think if you scale up your cat hulls x2, add centerboards and maybe try a slightly bigger diameter cylinder but possibly shorter you would have a great craft! It would be cool to have your centerboards attached to standardized holes as well so you can move them forward and aft along with your cylinder to get it all balanced and keep the hulls from digging into waves. Choosing a hull design like a Hobie 16 cat may be better suited to this experiment.
as these big rudder act like a fin, i belive the centerboard can be also in front of the center, but as they are very back, the bow will always go down wind.
also i would use long and thin hulls, lenght to beam ratio at least 10, as this is very effective, for ex. like all the military vessels.
plus some dimples and maybe a wider and lower drum an it should go great.
but anyway big effort and awesome speed, just nice!!!
@@flyingfamily1203 spot on. Also this will increase the distance between the rudder and the point the cat rotates around. Now the keels are fighting the rudder since they are both behind the center of pressure. So it would also increase maneuverability.
@@dropjesijs Came here to say precisely this.
A piece of string makes a wonderful recovery device, when you attach one end to the boat, and the other to the shoreline. This is best accomplished prior to sailing
Or, a Fishing line, on a Fishing Rod & Reel! đ„Ž
Unless u want to get wet
Being belt driven, options to add a double rotor in tandem or side-to-side. Might assist efficiency, balance and stability...or make it all worse :( Hope you have another go! Great channel!
Could use 2 motors tho to make it equal weight . belts tend to be kinda dense
definitally needs a trimaran design to stop cap sizing especially if he does 2 Cylinders
Gyroscope time
Yes was thinking the same thing, if you have them close together it may create a bit of Venturi effect making it even more efficient
If you do one with a double rotor try it with one clockwise and one anticlockwise to see if they help each other.
I loved your prototype. What drew me to this video is my passion for sailing boats and the idea of a rotor sail.. a few things I've learned about sailboats that could help improve its performance; in a traditional sailboat (mono or multihull), the boat moves forward using wings in the air and wings underwater acting in balance to generate a specific motion of the hull. The center of effort upon the wing in the air (sails) has to line up with the center of lateral resistance on the hull, the center of effort can be imagined as pushing a stick from its side across a table. Directly in the middle of the stick it will move straight forward, to either side it may spin on the center . For this reason , the two wings are aligned perfectly so that the boat doesn't "spin" upon those axis.or in seamans terms, go to weather or fall offwind.. sailboats are also ballasted with weight at the very bottom of the underwater wing , a keel. This is to keep them from becoming top-heavy and capsizing. On a catamaran there are two rudders that act in unison on each hull . Having only one can cause you to spin. There are also two keels on a cat. The keel and the rudder are always in line to ensure the boat sails straight (in most vessel designs). I loved this video and I hope you improve on the design and make a boat that actually sails very well with with the magnus effect!
Great video. I'm glad you're experimenting with the magnus effect. It's just one of those things that tugs at my imagination and wonders if there isn't more we can with it.
It says the comment was posted a day ago but the video was uploaded half an hour ago
@@kshitijpatil639 Patreons get early access :)
@Dave Doherty A cone halves the effectiveness ,for a problem that could be solved by leighter rig and better hull righting moment.
@Dave Doherty Lower cg is good. His rotor was waaaay to heavy per scale. But whether you contra rotate in one mast or two, you STILL negate the lift from the other "spin"
Its strictly one direction or the other with the spin orientation.
@Dave Doherty Yes, the whole concept relates to the Bernoulli effect, but cone shapes are waaay less efficient than a cylinder, as the speed of the outside surface is higher at bigger diameters.
Its height isnt as critical as its out of scale weight. he should be using thin mylar for the cylinder walls.
Iâm so glad youâve uploaded again- Iâm really looking forward to the next super speed boat video too.
Thanks! It's currently on my workbench and is being rebuilt for the winter months.
two parallel rotors(to vectorise the thrust/lift)
or
one flap (as in conventional wing) will be helping in further development if you are planning to approach Version 2.0
and the Sam guy is mandatory for your future project's susses
Actually one rotor is enough, as the rotational speed of the rotor affects the amount of bending of the airstream. I am not sure it was considered here which might explain the control issues.
I thinking two rotors and counter rotation so lower center of gravity and no crabing
@@aurigo_tech i will try to do some elemental analysis.. if I get some time after my college
@@Shreyam_io Please share your results!
Awesome work, James! đ
Looking forward to see the improvements you come up with!
Stay safe there with your family! đđ
This little rotor produced way more thrust than I expected
That's so cool! It's similar to the ones being tested for full scale ships
The fact that I landed on this channel is not thanks to the CZcams algorithm, but rather the recommendation of DIY Perks.
Very interesting channel with wise advice in the comment section according to the motto tinker and think along.
Conclusion: subscribed immediately!
If you add the keel in the centre it may help it track more in a straight line and if you add a weight at the bottom it will make it less likely to flip over.
Sam's a true champ for jumping into the lake to save your capsize, not once, but twice!
I don't have anything to contribute, but I love to watch your creations. I'm loving wherever curiosity takes you.
I think that part of your stability issues are from the rotor being placed behind the center of hydrodynamic pressure on the hull. Eg when the rotor produces a forward thrust, it is pushing behind the point at which the hull wants to naturally pivot in the water. Itâs currently a positive feedback unstable system. Itâs analogous to trying to drive with a trailer in reverse and keep it straight, rather than towing it, where the trailer naturally wants to stay aligned.
Perhaps a vane to direct the airflow coming off the rotor could be used to enhance directional control
That would work, but adds complexity and weight to the rig. Better hull direction, and slowing the rotors as the wind moves off the beam, would be the most efficient method.
@@dnomyarnostaw I would have thought a vane fixed at top and bottom and driven by a servo wouldn't be any more complex than a water rudder fixed at one end
@@benosborne7890 It more complex because it would hsve to be adjusted for every little change in wind direction, snd boat course. It would potentially be and difficult to cope with ad a 360 degree boom on an ordinary yacht. A rotor alone handles wind change automatically because its is perfectly round.
A shroud or vane may be useful when the wind is more in front or behind, but then you might as well make it a sail, as the windflow to the rotor would be all broken up and sliwed down.
Look promising. Thanks for sharing what you use to seal you boats.
Great video. It looks like there is some promise using the magnus effect in place of a sail. The hull design really should be a catamaran or trimaran. With the amount of surface area and the need for the rotor to stay near vertical, a cat or tri is your best option. You need to look at your center of effort for the rotor and try to balance the keels and rudders(make two) so that the underwater resistance matches(but a bit toward the back of the boat to ensure rudder authority) the rotor generated side forces.
Swath
I don't particularly see how spending energy in rotation nets any gains over a traditional sail
I think you need to move the Keel forward closer to where you want the Cp, that would prevent the boat vaning into current and keep it more on track.
"I've see other people struggle a bit with their 3D printed hulls." Haha, a cool shout out to RC testflight.
Haha, yeah he has some pretty cool stuff. Especially the autonomous aircraft
@@Robot_Child_Productions solar catamaran tugbot isnt all bad either.
Fair
I love this, please continue exploring
Really enjoy your films man... just remember it's not failing its learning and funny ....
Cool work! Looking forward to more innovations
Absolutely one thing you proved to me, that you have a good friend any friend that would jump in a lake with nothing but a nickers (I think itâs you call them) is a friend indeed
What you call a keel is in a fin centre board and is like an under water (symetrical foil) wing. It is there to counter the leeway force vector generated by a sail or rotor in this case. The fins needs to be placed in a fore/aft position that lines up the foils centre of pressure with the rotors centre of pressure. So basically in a similar fore/aft aft position as the rotor. Where you have the fins, is just inhibiting the rudders from being effective.
Sails are designed to reduce healing moment in strong winds but to use the wind gradient effect in lighter winds by exploit the faster wind aloft. Sailors make adjustments to sail shape, camber, twist and effective area to match the conditions. It's complicated, Your rotor, can't do that but you could make it conical so that you have more area down low than aloft. This would lower the magnus reaction force reducing the heeling moment (reduce risk of capsize). Also make the top of the rotor very light weight so that it doesn't overbalance the boat like it is doing when it heels.
Also, your fore/aft weight distribution needs to be on the centre of buoyancy. Even with moving the rotor aft, it isn't aft enough this is causing the boat to capsize by tripping over the lee bow.
Better success next time.
Version 2 please, I have always been interested by the magnus effect.
ProjectAir seems to become the channel of failed experiments. âOh no! The rudder fell off!â. But somehow it makes this channel stand out. I love it. Keep up the fun stuff. đđ»đŹ
I really like the channel because it doesn't just shows the finished and functioning project but also the fails
From a pure scientific point of view an experiment is not failed if it produces a clear outcome and the procedure is sound and not compromised by outside circumstances. The success of an experiment is not dependent on whether the outcome is expected or favourable.
Hypothesis: clamping the rudder on with a maggot screw without filing a flat surface into the rudder shaft will do.
Results: rudder falls off
Conclusion: Nope!
Not failed at all.
Sam's the man, well done you guys, bet a sequence will follow in the near future.
Full sized catamarans have a rudder on each hull working in tandem. A keel on each hull will also help with directional authority. More hull volume forward will also be of benefit (as someone else suggested). Nice project. đ
Great job, keep up the fine work.
I see quite a few comments on putting the keel more central. They're all partially right. It's a question of center of effort and that's both with regards to effort generated by the rotor and the aforementioned keel. Clearly this can vary depending on the wind angle with respect to vessel heading etc... I hope that helps and I hope you go for MK2.. for what it's worth I think you should stick to the catamaran but with larger hulls for more buoyancy. You can maybe put them further apart for more stability...
Sick!!! Looks so cool
The boat was fine. It just needed to be wider, so the boat won't topple over. Maybe add a flywheel spinning opposite the rotor to oppose the spinning force.
or add a second rotor
Really impressed. Definitely outside the square innovation. Well done sir
Excellent work! Very promising.
Always great to see Flettner-Rotos popping up again. Anton Flettner would be proud! Also good to see more and more commercial applications for them.
You didn't mention it so I don't know if you did consider this: the optimal speed of rotation depends on the direction of the wind (and perhaps windspeed as well?). As it essentially bends the stream of air more or less. So considering this could solve the control issues and provide more thrust.
I don't know about the math behind the optimum rotational speed, but a series of tests for different angles of attack against the wind could give insight.
Put the keel further forward, the water pushes the nose in the wind atm. I sail myself, and i think that might fix your problem. Keep going! đ
Also, the lift on the Rotor tend to pull the short hulls towards the wind.
Nice prototype, the simplest way to gain stability would be to use a truncated cone instead of your cylinder.
Using a small slope, the bigger base downward will produce a differential in the thrust pushing the down side (bigger base) stronger than the top both against the wind and using the magnus effect.
Having a quick swappable module with a regular sail and another with the rotor would allow an interesting comparison.
Your channel just showed out of nowhere kind of like stuffmadeheres did and I see huge potential. Your explanations and overall ability to keep the video entertaining is extremely professional. Love the stuff you're doing. I will be once work dies down starting a channel on lasers much like the legendary StyroPyro
Years ago I used to have an "RC Aircraft" group in an international website, before I handed it off to another member. Being the son of a scientist, this channel is extremely interesting to me.
For V2 Add a second rotor, rotating in the opposite direction it should help stablilty and direction catrol, a lot of the ships disingles i seen this on always had two.
A Finnish cruise ship was the first passenger ship that had a Magnus effect sail installed. It had it on for a few years as a test to see if it improved fuel efficiency. Apparently it does improve fuel efficiency "up to 20%". You can google "Viking Line Grace Magnus" to find some info on it.
I wonder if you can gain efficiency by also having a bearing up at the top of the rotor and holding it in place with some carbon fibre rods.
Certainly if you decide to ever scale this up I'd recommend it, those bearings are probably losing a lot of efficiency dealing with torsion.
Looking really cool!
Definitely need a bigger boat though. It's top heavy. Your boat has to have the right dynamics to countermand the effect of the mast leaning so it rights itself. Lots of ways to do that.
Maybe put the outriggers out farther on each side than the mast is tall and give them a little ballast... and a bit bigger. The idea is that when the boat tilts, you want the downward force on the outrigger out of the water plus the upward force on the outrigger in the water to be greater than the downward force on the mast.
This is pretty cool! The real world applications are already happening! Large bulk carriers and cargo ships are starting to be outfitted with the Magnus effect masts to make the vessels more fuel efficient.
Great video as usual!
They're called "Flettner rotors" en.wikipedia.org/wiki/Flettner_rotor
A wind-powered boat. What a splendid time to enjoy modern technology.
Lowering the centre of effort of the âsailâ would have been a good improvement
You need; two rudders, two centre boards or keels, further aft placement of cylinder to reduce pitching moment and enough righting moment to counter-act the roll moment of the "sail". The cat is a perfect platform but the height and width are issues. Less height to reduce roll and pitch moment, more width to increase righting moment (stop it getting blown over) and more length to increase pitching stability (stop it nose diving) - or a smaller cylinder. Centreboards (well placed) are essential otherwise you'll mostly be blown downwind. Happy to talk.
You also need a keel/centre-board to stop of from going sideways.
When you undertake experiments on the water, a bit of pre-planning is in order. Namely, a recovery device for the experimental craft. Here in the states, what I have used in a very similar situation, is a children's fishing pole. It is only about 1 meter long, and it comes complete with a preloaded reel and a casting weight. IIRC, it was only about $10 at Walmart. On it's first outing, I used it 4 times, big success. Truthfully, it was the only success on that first outing. On the second outing, I simply attached the fishing line to the boat and set the casting release. The line just spooled off the reel as the boat made headway. When it needed to be recovered, it was a simple matter of picking up the fish rod and working the reel.
I do not know if fishing is as popular there in the UK as it is here in the US, so I don't know if a child's fishing rig is easily obtainable over there. However, I'm sure you could print up a simple reel on your magic 3D printer. Just make sure it has a provision for holding enough mass (perhaps a stone) to keep it on the shore as the line pays out.
About the magnus rotor, I would like to offer some suggestions. How about a dimpled surface, like that of a golf ball. I seem to remember reading somewhere about that improving the performance of the rotor. Also, you might like to experiment with rotors of different diameters. I believe there may a correlation between diameter and efficiency at different airspeeds. Think larger diameter for lower speeds, thinner for faster speeds. I've also seen a drawing in which the wind was also the driving force that spun the rotor. There was a vertical windmill arrangement deployed around the center of the rotor, at a considerably larger diameter. There was a means of reversing the pitch of the paddles in order to reverse the rotation of the rotor. I only saw the drawing, I do not know if such a thing ever came to be tested. I'm just offering up some ideas here. I really enjoy watching you tackle the different designs that you do.
Oh, and don't forget your Wellies next time! đ
You should widen the gap between the hulls and put long heavy keels at the longitudinal CG of both hulls.
Actually thought you brought a child with you that started screaming when it tipped over lol
đ
"Ohh, no, my rudder's just fallen of"... Best summary of this channel that I've ever heard!
Much respect to the flat mate retrieving the boat.
See the January 1984 issue of _Popular Science,_ I remember this from reading that issue, and looked it up.
Extremely cool.
you really do need to make longer videos i really enjoy them just wish they were longer. đmerry christmas
Good job experimenting young man!!
Crazy cool!
I am surprised it generated as much thrust as it did. A good demo, for sure.
With two separate Rotors not only the drag would be more directed, but you could also provide steering by different rotation velocities or directions.
Version 2. Yessssssss!
good job man! and some suggestion, 1. shift the centerboard close to the c.g. of the boat. 2. possible to have some sort of flap/rudder down stream the sail to have some wind steering? (the reason need centerboard to balance lateral force). 3. how about a conical sail to improve stability?
Stumbled across your channel. Interesting project. I would definitely go larger on the hulls and more keel area. A Turbo Sail would be a cool project as well.
Love this channel!
I have been into RC's all my life, grew up on the water and had many rc boats, the one thing most important if your going to be on the water is this, have a chase boat, like a blowup boat or rowboat, very important, especially if the water is to cold to swim in, or a chase rc boat with grapple hook on a fishing line and float, therby eliminating having to watch your boat float away and not being able to retrive it. have fun and good luck on your project, very interesting, I once had a cat sailboat, was very fast and fun, went like a bat outta hell lol
the technical term for a such a sailing device is Flettner rotor invented by the German engineer Anton Flettner.
and as mentioned a katamaran is not the optimal choice here. the boat can neglect internal volume for cargo or passengers a hull desing like the one used by J-class racing yacht would be the optimal. It features reduced drag compared to a ccargo ships hull and would have different to a katamaran self righting properties once the "sail" is "reefed".
This is a great video đ
nice vids love them keep up the good workl even though i feel stupid watching your vids
Ah, cool project dude and didn't know you were in sheffield! I was at Bolehills the other day kiting!
Yes make a version 2!
This was the perfect video and was most interesting
A few notes about the lack of direction control. I am a young man in Canada that does a fair amount of sailing, on primarily a prindle 18. The hull designs firstly are a-symetrical, therefore meaning that in theory that would eliminate your need for daggar boards. The real issue I see here is that you dont have your center of pressure in the right spot. from the looks of it the boat keeps moving straight into the wind, therefore meaning that your center of pressure is too far back. Also It seems that the issue was worse the second time after you had moved the rotor back, supporting this theory. Theres a lot of science behind this, but looking into exactly where the center of pressure is might be a helpful idea. I have a feeling that making the boat longer to counteract the torque applied by the forward force at the top of the rotor while simultaneously getting the rotor in the right spot might help. On a side note adding another smaller rotor toward the front might do the trick similar to the way a jib or the front sail on a boat generally works. Just my thoughts. Anyways, great video, keep it up!
A lot more ballast on that. Not just the wind's effect once any force is exerted, but the rotor drum is also heavier than any sail. Other than that, may need to compensate for any gyroscopic force too.
Very cool! I'd love to see a profile for a kite driven "sail boat".. If you have a with spreaders at the top of a mast (so that the lines are spaced apart appropriately and don't tangle), you could run the kite on a very short retractable tether, so have good control over it.. Then all of your "sail" is in the higher loftier winds.. Should be much more efficient.
It would be interesting to attach the mast to a slide circling the boat so that it's always pulling from the leeward side of the boat, instead of the centered, which should decrease heeling, though that would effect any plans for routing the lines.
Very cool! for sure worth another try. Hope to see the Rocket plane fly. Maybe a Space Shuttle with with full booster , external tank ?
Well done. The boat swamped over because the catamaran hull was not large enough to handle the effect of the wind on the vertical cylinder. Maybe weighted keel fins would also help keeping it upright.
the center of lift of the rotor and the center of lift (resistance) from the combination of keel and rudder need to be in roughly the same lateral position on the boat in the direction of travel. With the keels so close to the rudders, the force of the rotor easily overpower it. The keels should be in front of the rotor. while the flat plane of the keel and rudder will work, you would really benefit from a true foil shape as they will generate relatively free lift to overcome the side force from the rotor. Last point....the further you place the combined center of underwater lift (resistance) behind the rotor, the better the boat will tack into the wind but at the expense of controllability at slow speed until the underwater lifting surfaces get enough speed to overcome the offset forces.
My wife and I were talking about your video and she asked about a collapsible rotor. The thought occurred to me that it could be built sort of like the old Tunnel Fun toy, a coil of springy material (maybe fiberglass) covered with fabric, set on end, with a rotating mast inside to drive it.
Another thought I just had is that if the rotor were tapered, there would be less lateral force aloft, where the moment arm is greatest, and the boat would be stabler. Also, slightly less weight aloft. Somebody must have thought of this, as it seems so obvious. Regular sailing vessels have sails that taper upward, either approximately triangular sails or, on square riggers, smaller sails aloft.
As the magnus effect depends on friction between the surface and air, you should be able to increase the efficiency of your rotor by covering it with a felt or some other material that causes lots of friction with air. Something close the surface of tennis ball could be optimal.
Needs ballast. Would love to see v2. Keep up the great work.
Keel needs to be at center of pull from the sails to increase sterling. Move keel forward to turn easier. Great video. thanks mate
Very nice project
Longer pontoons along with a wider mounting may help with stability. Perhaps a trimaran configuration. Some fins and ballast as low as possible would help with straight tracking and balance. Even if the fins are nice and heavy to help.
As a sailor, I think what you need is to move the keels forward so they are directly in line with the rotor when looking from the side of the boat. The purpose of them is to counteract the lateral forces produced by the rotor which try to drive the boat sideways. Also if the boat ever points directly into or away from the wind, stop the rotor as it's force will be directly sideways causing the boat to capsize.
Also, the keels and rudder on a sailing catamaran would normally be significantly larger than what you are currently using.
Sam is the real hero of this video! That look very cold!
Wow, we have drone delivery stuff here in Finland đ«đź? Didn't know. Pretty cool.
I will not let the inventor of these fascinating sails go unmentioned:
Herr Flettner
I would expect to see more vertical wind turbine sail boats. The turbine isn't affected by the direction of the wind at all, and it is linked to a drivetrain that powers your typical props.
Tests show the Flettner rotors produce waaau more propulsion force, which is ehy over a dozen modern merchant ships use thrm, and none use vertical rotors, excepa few experimental private small craft.
You should definitely attach a thread or something to retrieve when testing in open water mate. Great work. Cheers!!
I think building the hull much like a standard monohull sailboat might help with the direction it goes in and stability.
This is a flettner rotor and I did this 20 years ago at school. It worked too!!
Check the Flettner rotor ships. That was a decent sized commercial cargo ship attempt with two large Magnus effect rotors. A former colleague of mine actually saw this ship in the Mediterranean when he was a boy.
A wider beam would help counter the toppling effect of the rotor. The rotor is basically too big for the beam and has made the boat "tender". Larger fin keels more centrally positioned along the lengths of the hulls would also help with directional stability. The rudder will work fine if you have more speed. It would help being centrally positioned between the hulls, but its efficiency directly correlates to the amount of water flowing past it. A tiny rudder would work just fine if the boat went fast enough, and a huge rudder would be fairly ineffective with very little forward motion. Hope this helps. Good luck.
If you build another catamaran hull, you should consider making the hull much wider to give more stability. Remember, when you have that large cylinder spinning, you have to consider gyroscopic precession. When you have the wind coming in from the side and your cylinder generates its forward pulling force, gyroscopic precession will occur and your boat will try tip over into the wind.
Thank you Sam!
Boats are intended to rotate around their keel, as that part resist the hardest to sideway movements. You put the keel at the back of the boat that cause its rudder is barely effektive due to the very small leverage, however it give very high leverage to the wind to turn it away. If you want good control and stability, move the keel about to the center of gravity, or a littlebit even further to the front!
Silly as it sounds you might have done fine with a larger mono hull and multiple Magnus spinners just make sure you put some ballast in the bottom. Using two or more you may be able to use them to not only provide propulsion but steering as well. Set them up like on a traditional sailing ship and you'll probably have quite a bit of luck.