OCSS-059 The Fastest Way to Build a Foil - For a Rudder, Daggerboard, Skeg, or Keel

[@donovannagy4303]

I love what you're doing and joyed that you're putting this out for everyone to see your progress and inspire others. You have another subscriber.

[@CopperCreekCuts]

That ASMR foam cutting at the end would make a killer short. No music, just the sound of the cutting turned up a bit.

[@ocean_capable_small_sailboat]

Good idea, some shorts might help me meet my subscriber goal a bit faster.

[@jimwoods9551]

Light water spray while foaming helps set it off and keep up density.

[@Garryck-1]

Something I've forgotten to comment on, Cap'n Perry, is your inspired use of jigs for tricky tasks. Speaking as someone who loves nothing more than making a good jig to simplify a task, I must say how impressed I am with your solutions throughout this build. More than once I've gone "Damn.. I never would have thought of doing it *that* way!" Kudos! 🏆😎👌👍

[@ocean_capable_small_sailboat]

Hah thank you very much! When working alone you rely on those jigs as extra hands for sure.

[@erickramlick2079]

Lo-Fi remix of Debussy was an excellent music choice! Awesome as always!

[@ocean_capable_small_sailboat]

Ayy, thanks Eric. Appreciate the visit.

[@catherinesecula5287]

i love that his work shop is top clean , .

[@knolltop314]

Welcome home!

[@markthomasson5077]

My thoughts on making foils. Make a half (side) female mould. Form two pieces. Turn one and join together. Of course only works for straight parallel edge foils.

[@theGrowStudio]

Another great video, Perry!

[@diogod1801]

good job!

[@christophe6065]

Thank you for this vidéo. I was suprise to see that you were filling the whole skeg with froam ! But you said, later on, that you could have filled only half of it.🙂 Please excuse my english (call from France...).

[@polderfischer8565]

Very well build👍 As i saw the amount of foam i thought: Captain, that stuff expands😮 Wenn well in the end😊

[@ocean_capable_small_sailboat]

It was pretty comical in the moment. Lesson learned!

[@markgallagher1376]

I was thinking the same thing. Lol

[@johngrant1337]

great info ,thanks

[@jacktyler7599]

Nice to have you back in action, Perry. Yet more watchmaker action!

[@quinntalley1681]

Nice job on the foil. Love the Total Paycheck reference 🙂 Guess they are not going to sponsor the channel.

[@ocean_capable_small_sailboat]

I tease. I actually have ordered almost all my fiberglass and peel ply from them. But all this stuff is expensive. Anyway, once KZbinrs get heavily sponsored I lose interest in them. I'm not too interested in becoming that.

[@OMIF1]

I purchased a Great stuff pro gun a few years back. I highly recommend the system to anyone working with this kind of build.

[@Stupha_Kinpendous]

Man, I love EPS foam. It's so satisfying to use, and super versatile.

[@georgewashington7444]

Just in time for me to consider this technique on my Paradox rudder build! Thanks

[@DarrenMalin]

very clever well done Sir :)

[@ocean_capable_small_sailboat]

Thank you! Cheers!

[@michaelspooren9213]

Very informative and interesting. It's progressing step by step.

[@Centerlinefawnstudio]

Interesting project and well done. From SV_Holly13

[@samijokinen6923]

Nice work!

[@crawford323]

Hoerner, a famous aerodynamics and drag expert in the early 50's tested many shapes and airfoils. In his book he has the width to length ratios listed. For example a good width to length ratio is 3.71 to 1 which results in less drag. This ratio can change depending on the length. Surprisingly a big creators of parasitic drag is how the airflow is affected by how the airfoil of course called hydrofoil is connected to the ship or fuselage. Pretty fascinating findings actually.

[@leo169]

Total Paycheck... Nothing like boat building to test a budget out. I see on the 3D model you showed at the beginning, your keel weights extend forward. Would be interested to hear your reasoning for that? I would have thought you would want no catching points below the waterline. Hooking a line or net on such a short light yacht would be a whole lot more excitement than I would want. Like your skeg construction there Cptn Perry, are you thinking the same for the keels?

[@ocean_capable_small_sailboat]

A friend/viewer put the boat in CAD and drew the keels that way. Steel construction with lead bolted on. I think he was going off some Class Globe 580 keels he found. I agree with you though, I think the final design won't have the keel weights extending forward at all.

[@leo169]

@@ocean_capable_small_sailboat Fair enough. Nice to have a 3D model to play around with...

[@PineappleAdrift]

Really cool technique! I need to try that.

[@mndad2201]

cool episode! I like how you mix up the work to keep it interesting. :)

[@LEGOWENTV]

An alternative method would be to cut a bunch of templates in foam and glue them together…like a bunch of cake layers where the layers are the perfect shape of the template. Then glass the whole thing when done. This method would insure your shape is not corrupted.

[@ocean_capable_small_sailboat]

The problem with that is the foam sheets are really expensive. I'd rather have the PVC foam stringer inside, along with expanding foam. Strong and cost effective.

[@toroddlnning6806]

@@ocean_capable_small_sailboat are you going to build some kind of diy windvane?

[@washy934]

@@ocean_capable_small_sailboat I don't think he was inferring that, you could use exactly the same mm^3 of PVC but preformed contours, layers effectively on the other axis to your method, and still fill the void with expanding foam - the question maybe over the wastage creating the voids vs solid pvc...

[@ocean_capable_small_sailboat]

@@toroddlnning6806 Yes, looking forward to it. I will make a trim tab wind vane system.

[@rogerharrison8355]

Hi from the uk. Perry's videos are fantastic but what impresses me most is seeing perfectionist in action, and such a great guy, I wish him well. I wonder where he got his plans from and how long it took to build?

[@ocean_capable_small_sailboat]

I started the build in Oct 2021. Going is a bit slow bc I juggle the build with a full time job + little kids. I drew the plans for this skeg. I started with plans I bought for a 14' boat, but ended up re-drawing a lot of it to my liking.

[@DowneastThunderCreations]

👍👍👍

[@peterb9038]

Hello Cap'n Perry,, welcome back. Just wondering why didn't you make it into a full skeg to protect the rudder,? As you are going to be offshore it would give more piece of mind.

[@TheMadSqu]

Make an expanding foam ASMR channel!

[@homemort2265]

Nice. But I thought you would add some ballast to the hollow space of the skeg, instead of foam

[@ocean_capable_small_sailboat]

I'd prefer to keep weight in the stern (and the bow) down. Neutrally buoyant / slightly negative buoyancy is all I want for the skeg. There will be plenty of weight in the keels.

[@kaisailor1]

I think it's more of a skeg than anything. Maybe even a directional strake or a balance strake.

[@cornishhh]

That's a good way of building a foil. Might it be easier in future to draw the outline of the foil. then put nails on the line and fit the foam within them? I noticed Yann is modifying Baluchon with a more balanced rudder. Would you consider twin lifting keels? I like the option of being able to run on to a beach and dry out like a dinghy, and to be able to get on and off the boat whilst floating in very shallow water. .

[@ocean_capable_small_sailboat]

I don't like the lifting keels due to the added complexity and loss of space inside. My idea was to be able to dry out the boat on the twin keels if I want. The two keels can rest on the sand. I haven't quite figured out the 3rd point of contact with the ground yet. Maybe a removable simple beaching leg on the transom, just long enough to be longer than the rudder. Still thinking.

[@John-Nada]

Yann built twin skegs now but I don't know why because I can't understand French and the translation feature doesn't work. If he did it you should probably do it too. Your boats are nearly identical. When his boat was heeled over it used to look like he lost a lot rudder control and even with a new larger rudder he didn't think it was enough? Maybe these boats need twin rudders.

[@ocean_capable_small_sailboat]

@@John-Nada Yeah, I'm not so sure. I'd rather go for less water resistance and stick to 1 skeg. It may very well be better to have twin rudders but I'm going to try it with just 1. It's much simpler and less build time. We'll see how she sails in the sea trial phase. 👍⛵

[@tonysutton6559]

As your skills and knowledge are increasing so well as the build progresses, are there any things that you did early on in the project about which you now think "I wish that I'd done XYZ instead of ABC?"?

[@ocean_capable_small_sailboat]

Yes. The main one is the jig and bottom panel. I would have built in 4mm ply base integrated into the jig for the boat to sit on. And I would have put 2 layers of 1708 over the top and bottom of the bottom panel of the boat from the very start. I put the bottom panel down and only fiberglassed the top of it. It'll be bare foam until I flip the boat over. Just would have been nice to have it very protected from the start.

[@tonysutton6559]

Did you consider filling the void with stones or scrap metal held together with liquid epoxy to add some weight at the lowest point of the boat to help prevent it going completely over in a knockdown situation?

[@ocean_capable_small_sailboat]

No, because it's not very deep and I don't want a bunch of extra weight on the stern. I used high density foam, and overall it's already pretty heavy. The twin keels will have lead attached and that will do the trick for righting.

[@james-gn9cq]

As built the shear web is dependent on the tensile strength of the foam. It probably fine because the foil is such a low aspect ratio but there should be a strong fiber glass connection between outer skins at the sheer web. If you use canned foam you’d be better off using door and window doesn’t expand as much and is therefore denser.

[@ocean_capable_small_sailboat]

Thanks for the foam tip, I'll remember for the next one. Since the rudder will be a much longer foil I will include a more reinforced stringer in the inside.

[@Garryck-1]

*"As built the shear web is dependent on the tensile strength of the foam."* Nope.. not in the slightest. The foam contributes nothing. All the strength is in the fibreglass. The foam is only there to tell the fibreglass what shape it should be.

[@james-gn9cq]

That’s my point. The stringer the foam is bent around is a shear web. It acts like the center flange in an I beam. There should be direct structural connection between the foils fiberglass side walls as the foam doesn’t contribute structurally.

[@ocean_capable_small_sailboat]

It is structural foam board though, with 90lb/sq inch compression strength. With all the layers of fiberglass I think water force on one side just gets evenly transferred around the perimeter of the foil and into the hull, and some can transfer directly through the stringer to the opposite side as well.

[@Garryck-1]

@@james-gn9cq - There *IS* direct structural connection. At both ends of the foil. The fibreglass sides of which are curved. And as we all know, curves are one of the strongest shapes around when it comes to distributing force. Whether your shear web is there, or entirely missing, will make absolutely *zero* difference to the foil's ability to resist pressure or impact.

[@jamesmorton7881]

lol, score the foam crosswise to allow the leading edge outer surface to lengthen. Better yet just get some 0.0315 ( 1/32nd ) inch G10 sheet for the surfaces. No messing around to get it perfect with no sanding.

[@ocean_capable_small_sailboat]

Why score the foam when it bends so well with heat? There are many ways to do this. Thin G-10 works too, but I don't have any in stock. I do have a lot of foam sheets however.

[@macrumpton]

I think using a hot wire to cut the foil shape out of thick insulation foam would be a lot easier.

[@ocean_capable_small_sailboat]

Just my opinion, but, I don't see how. It would be tricky to get a uniform and smooth shape. And you have to build or buy a hot wire tool. Epoxying the leading edge and bending the panels around a stringer is a dead simple way to get a great foil.

[@m1kalD]

Hot wire cutting works well for rc wings. But there is alot of technic and trial and error that goes into a good cut... for a few pieces I wouldn't be using it for the first time...

[@paloureiro]

I have a question about the strength of the skeg. As I understand, fiberglass has lots of tensile strength, but it`s not designed to counteract compressive forces or shear stresses that would occur when hitting something something, for instance.

[@ocean_capable_small_sailboat]

Another question is, do you really want your skeg SO strong that it tears the boat in half instead of just breaking where it is? I think that, sadly, just no matter what if you hit something hard enough it's gonna be a bad day.

[@DrSurf-fx4gf]

I thought that you were going to place twin keeles on this project? Just asking😎

[@ocean_capable_small_sailboat]

Yes we will get there eventually. Twin keels are coming.

[@arnekvinge6073]

This will give some boyancy down low. I was thinking of 3 improvments: G10 in the front as well and fill it with concrete. A shape that will not hook into lines, rope and so

[@ocean_capable_small_sailboat]

It actually already feels heavy enough now I think it may have neutral buoyancy, or at least I don't think it adds much buoyancy. I don't want concrete in there because I don't desire more weight that far aft. Even more fiberglass will be added later when it's attached so that will add weight. The leading edge is only 60mm, I don't think it catching lines will be an issue.

[@gunnarfernqvist4896]

Very interesting! Are you using polyester resin or epoxy? Since we on the other side of the pond they call the Atlantic Ocean can’t get Total products, it’s great to see other products here on KZbin that work and that we can get our hands on.

[@Garryck-1]

The answer (available in earlier episodes), is that the entire build is 100% epoxy all the way.

[@Hotzenplotz1]

As the foil is not tapered from the bottom to the top here it would have been easier and far more precise just to cut one or two horizontal profiles and use thinner layers of foam. Foam is also sold for bending purposes. The leading edge is way out of naca form and will therefore not be as efficient while the trailing edge is far to thick.

[@ocean_capable_small_sailboat]

I made the trailing edge a bit thicker to be stronger. moving a bit away from a "perfect foil" shape is an acceptable compromise for me. We won't be traveling mach 1 here 😉. Thanks for watching and commenting. Hope you stick around.

[@grandmajosephine383]

What kind of foam are using for the structure and is it stronger than plywood?

[@ocean_capable_small_sailboat]

PVC foam core is 90 pounds per sq inch compression strength. 4lbs/cubic feet in weight. Using foam sandwich construction method, you add fiberglass to each side and can certainly get it stronger than any plywood. Stronger by weight than even steel.

[@raytruck5799]

I would have used a template to cut out layers and sanditch layered it with glass between layers.. a router would have made quick work of it. Shape it after attached to hull and covered it with glass. That looks far too fragile.

[@ConfusedSoul24]

If you heat it up this way, you'll never have perfect symetry. The simplest way is printing a foil shape you want, transfer it to two pieces of wood, nail the two pieces to opposite ends of a foam block and just use a hotwire. It's faster than this and you get a perfect shape.

[@ocean_capable_small_sailboat]

Perfection is the enemy of progress.

[@GOAFPilotChannel]

Total paycheck 😂

[@ChimeraActual]

E glass and polyester or epoxy is very strong in tension, much less so in compression. A low aspect skeg, yes it is a skeg, should not be a NACA foil, but essentially rectangular. You are doing a lot of work for less strength and performance. A nice wedge shape piece of oak would serve you better. BTW, shaping a solid piece of anything to a NACA foil is easier and more accurate than any built up section. Why are you foaming the inside if you are certain it will never have moisture?

[@ocean_capable_small_sailboat]

Why would a rectangle shape have better performance than a foil underwater?

[@ChimeraActual]

@@ocean_capable_small_sailboat a skeg like yours is essentially the very low aspect ratio extended leading edge of a portion of the rudder, and while you might think your skeg/rudder is like a wing/flap it really isn't. Truth be told I don't know exactly what effect your skeg will will have on your boat's performance, it may have none. But if the skeg is asymmetrical it will probably cause a bit of a yaw in such a short boat. and who knows what it will actually do to the turning moment, in any case it will not improve the performance. Better to have a solid piece for the boat to rest on with rudder pulled and centerboard lifted. Easier to rep[ace in Tahiti anyway. BTW, I'm not down on your project at all, I think small boats are great. I raced 14' - 15' boats most of my life. In my misspent youth I was a boat carpenter for about 25 years with a speciality of shaping NACA foils. Back in the Early 80's, as I recall, while working in Miami I ran into a gentleman from Maine who had crossed the Atlantic, then recrossed it in a nine foot sailboat. He was in Miami to pick up a small outboard that someone had donated. He was a pretty big guy, and I was amazed. Unfortunately he tried to cross the Pacific and didn't make it. Best wishes.

[@ocean_capable_small_sailboat]

Thanks for the detailed comments. It's symmetrical, my thinking was I want water to flow around it with minimal turbulence behind so that it hits the rudder as a relatively clean water flow. And I want it to add minimal drag to the hull. I'm still learning though, we'll see how it all works out. Keep watching 👍.

[@ChimeraActual]

@@ocean_capable_small_sailboat Making one or more template(s) to insure accurate dimensions and to compared both sides will make your job much easier. Here are the numbers to create a NACA 0008 foil template. The first column is the percentage distance along the length of the cord for each half height (half of the total thickness of the foil). Multiply that by your chord length to get the location from the leading edge of each half height. Then multiply the second column by the length of the chord to get the half height at a given percentage point. Note that the maximum thickness point of the half height is at 30% and is approximately 4% of the chord length, x2 = 8% the full thickness of the foil. Example: Chord length = 950 mm. At point .15, the position of the point is 950 x .15 = 142.5 mm from the leading edge. Its half height mark is: 950 mm x.03564 = 33.858 mm. Complete the table and make a centerline the length of the chord on some appropriate material, Mark each % of length point along it horizontally, then mark the half height vertically at each point. Fair a line to the marks and remove the convex part. Use the template to check the dimensions along the length of the foil. 0.000000 0.000000 Leading edge 0.012500 0.012630 0.025000 0.017430 0.050000 0.023690 0.075000 0.028000 0.100000 0.031210 0.150000 0.035640 0.200000 0.038250 0.250000 0.039610 0.300000 0.040010 Max thick 0.400000 0.038690 0.500000 0.035290 0.600000 0.030430 0.700000 0.024430 0.800000 0.017490 0.900000 0.009650 0.950000 0.005370 1.000000 0.000840 Trailing edge While I could have got those numbers from Theory of Wing Sections, getting them from airfoiltools.com/ was easier.

[@sdcofer52]

Never say "this will never see any moisture" when building a boat. You are probably right, but you never really know for sure.

[@ocean_capable_small_sailboat]

Hah! Too true.