Kite-powered proa (boat) collaboration/comments

Added 5/26/07: Please read the comments below to see how the project is evolving. Design specs, goals, etc, have been modified after discussion.

Hi Folks,

For several years I've been wanting to build a kite powered proa. A proa is a kind of boat with a narrow hull and a smaller outrigger. These Instructables are about building a proa with a traditional sail:

These are kite-powered proa-like vehicles for land and ice:

Goals for the project:

1. Make at least one good boat.

2. Publish a good Instructable.

3. Work with interesting people.

I am definitely going ahead with #1 & #2. #3... anyone interested?

The Boat:

Generally it should be appealing/attainable by as wide a range of budgets and circumstances and skill levels as possible.

a. It should be fun to mess around with starting in about 6 or 7 mph of wind (3 m/s).

b. A beach boat, not an overnighter. Should be able to carry one or two people, a paddle, personal flotation device and maybe a sandwich and a water bottle.

c. Storable in a typical apartment (maybe even a dorm room?). I'm thinking a 2-part bolt-together hull like Wade Tarzia's above. Two halves, each under 8 feet long so they can be stored on end, maybe used as bookshelves as suggested by TimAnderson. What is a typical ceiling height? Mine is about 91"

d. Possible to build on a restricted budget ($200? is that possible? $400?). I'm budgeting about $500 but as a cheapskate packrat scrounger type I am hoping not to spend it all. Should also avoid necessitating rare and expensive tools.

e. It should be possible to make a "good looking" version if the builder chooses.... sort of financially and chronologically(?) scalable. Someone might want to build something as quickly and cheaply as possible, and another person might want to spend all summer working on the fine details and finish. The boat should be worth building in either case.

f. Should be able to take a passenger (is that possible if we rely on weight-shifting for steering?), but be sailable single-handed.

g. Possibly be adaptable to a traditional sail? Would this be hard? This is something I don't need for myself, but I bet someone will ask that question as soon as we publish it. If someone doesn't already have a kite, is it easier to build a kite, or a sail and associated mods to the boat?

h. Probably plywood stitch-and-glue construction main hull, but maybe carved from a couple of Styrofoam billets with a plywood stringer and/or deck? Leaning towards all plywood. If we fiberglass the whole boat can we use 1/4" interior luaun at $9 per 4x8 sheet? Is that more practical and cost effective than something like occume at $60 per sheet with glass on just the keel and joints? We'd need 3 sheets. Need to do some calculations on this.

i. Usable in flat water, chop and small waves (and bigger waves?). Mine will be used mostly at an ocean beach.

j. Steerable by weight-shifting, i.e. moving towards the front or back of the boat. No rudders or daggerboards. Maybe paddle-assisted steering when carrying a passenger/helmsman?

The Instructable:

a. Should be a good read, even for folks who won't undertake the project.

b. Doubles as an Instructable on how to collaborate to make a great project and a great Instructable.

c. Represents everyone involved in the project in some way.

d. Gives the potential builder a rough "how to sail it" as well?

e. Presents the reader with several options for materials and/or construction.

f. All the regular "what makes a good Instructable" things.

The Interesting People:

a. Everyone is interesting in some way or another, right?

b. Some people like to do research on the web.

c. Some people have built boats.

d. Some people some know about wood, or glue, or paint, or kites, or sails, or writing, or...

e. Maybe someone will build the boat concurrently so we'll have pictures of two or more versions at various stages when we publish the Instructable.

Let me be the first to sign up :) I have been using kites to get around fields, beaches, frozen lakes and the ocean for 10+ years. I make my own kite boards and have made my own kites (I use commercial kites now but still love my homemade plywood boards). I've done a fair amount of web research on proas and plywood boats (and some on tarp boats, canvas covered canoes, surfboards, etc.) but I have never built a boat. I experimented with a busted up, rudderless old hobie 14 for a while, but my homemade foot-steerable rudders broke almost instantly, and shortly after that I had to abandon the boat because I moved to a place where it couldn't be stored. It was enough to get me interested.

I'm pretty confident I could build a usable boat as a solo project but I want to see how much better it could be as a collaboration, or at least having a few folks commenting on my ideas.

I have a small assortment of cheap power tools. I've used epoxy and fiberglass a few times and I have some on hand.

I have permission from my lovely bride-to-be to use part of the kitchen, part of the time, as my workshop (that's true love). I also have a small are outside where I can work but I can't leave anything there.

The pictures are my initial hull ideas. For each hull one pic shows the hull from 3 angles and the other shows how the side pieces would fit on two sheets of plywood. A third sheet would be needed for the deck and a fourth (of thicker stuff, I would guess?) for the frames, bulkheads, etc. I'll attach the files for the hulls too. You can get the freeware to view and edit them at

The simple V hull would mean less cutting and joining. The other one looks better (in my opinion) and can float more weight with the same amount of plywood.

Could instead go with a flat bottom like Wade's.

Let me know what you think.


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hi there, I am currently studying at Portsmouth university, for my dissertation i am designing and building a kite boat that can use a old windsurf board as the hulls. It is in similar design to . i would be interested in talking to you about what your doing and likewise help you out if i can. please email me at thank you and good luck Nicholas Harvey
flywoodkb (author) 10 years ago
Here's what the first third of the hull looks like so far. Red frames in the third pic are corrugated plastic, placed there temporarily. I think I'm going to cut the frames down from 3 to 2 on the end sections and 3 in the middle section. There will be a deck for additional stiffness and strength. Any comments on that plan?
Looks great! The sections seem short -- is this a three-piece design? I missed some discussion, I think, after I cleared out my cookies and the Instructables robot stopped sending me notices of new posts. I like that V-bottom, something I am considering for my 19-foot proa. As far as sections go, I am not the judge. I generally build things too heavily. However, I guess I would leave this as it is in the third photo. The hull will be light enough as is, so don't remove any more bulkheads, which are important in the strength of a thin hull. The gunwales will take a beating, and also help with strength, so consider using a strap of quarter-inch thick oak for gunwales (available in the moulding section of comemricial home improvement places).
flywoodkb (author)  Wade Tarzia10 years ago
Yes 3 sections. I am using 5' x 5' panels. I thought about joining them into (2) 7.5' panels, but it seemed sort of redundant... all that extra gluing, glassing and sawing. I'd probably rather have a 2-part boat, but I think I'll keep it assembled on top of my truck for most of the summer so the extra bolting-together time doesn't bother me too much. I have enough 3/8" for 3 frames per section, so I'll take your advice and go with that. Oak for gunwales sounds good, too. Must say I'm very happy with the bottom shape. It looks very boat-like. Very satisfying to see the form come together while twist-tying. I think it will look better in my living room in the winter than the two-panel design I was originally considering, too. Maybe I'll rig up those deck hatches so that I can mount speaker cones in them for off-season use, heh. Speaking of missing discussions... off topic, sort of, but have you found a way to receive notifications for comments on Instructables and forum topics that you didn't create yourself? In other words, do you have a way of being notified when someone posts something to this topic but not in direct response to one of your comments? I put in a request for that capability but I still kind of wonder if there's an existing feature hiding somewhere.
OK, 3 sections can be good -- more manageable if you travel with your proa --airplane cargo-hold friendly, I mean. Also, the proa's biggest strain will occur in the middle section, so for that you have a one-piece module to distribute the stress better (at least I think that is what will happen). I have an enduring fantasy of bringing a 3 or 4-sectional proa to cruise around the Blasket Islands in Ireland, which I visited once by tourist boat -- fantastically rugged and beautiful terrain, and islands you can sleep on with few problems. Not sure what I did to get automated messages, and what I did to lose them for a while.
flywoodkb (author)  Wade Tarzia10 years ago
Brief update: Frames are cut. Made from 3/8" baltic birch. Frames for the section ends temporarily hot-glued into pairs and planed to the same dimensions. Considering what to use for gasket material between sections. Maybe craft foam? Foam board with the paper stripped off? Thin pink or blue styrofoam? Some kind of weatherstripping? A couple of beads of Great Stuff or sIlicone caulk on one side? Some kind of automotive gasket-in-a-tube?
On my take-apart dinghy I used 1/4" stainless bolts with fender washers and chunks of old bicycle tube as gaskets, which worked well for a while but eventually started to leak. Wetsuit material sounds like it would work better, but what would work better still would be to not drill any holes and instead attach the 2 pieces with stainless draw latches below the waterline. I'll be trying it out this summer and will let you know. If it works I'll put recessed pockets in the hull to reduce drag.
Sorry for delay. I cannot reply to Instructables from my home computer and had to get to office; don't know why this is. Any way, I used NO gasket between my sections. I built "wells" so that the water could leak through bolt holes up to the waterline (so the well-bulkheads are taller than my waterline). In fact, I rarely had more than a couple of inches of water in the wells since the wood swelled around the bolts and sealed off. But I used "real wood", and playwood will not swell like that. Gary Dierking (you have seen his Wa'Apa design I guess) uses wet-suit foam washers on both ends of the bolts, whioch works fine, he reports. If you cannot get wetsuit foam (and my old scuba suit has just about disappeared over the years from scavenging it for foam ;-) you could try sleeping-pad foam from a camp store. You might also try a bead of flexible stuff around the edge of each bulkhead (silicone or polysulfide boating sealant) but I do not know how evenly it would compress once you tighten the bolts (try a test section?)
flywoodkb (author)  Wade Tarzia10 years ago
I think I have a couple of old wetsuits around, mostly unmolested thus far. That sounds like a good option. I've been to Dierking's site, but I don't remember seeing a split hull design... I'll have to make a visit there tonight, and one to your site. I suppose if I made wells small enough I wouldn't have to worry about this, but one reason I wanted to go with a sort of sealed hull was that I won't have hands free for bailing. Also thinking that my waterline might be pretty close to the gunwales if I take a passenger.
Reply to myself ;-) I really did mean "plywood" and not "playwood" but the error makes an interesting subconscious slip, perhaps! Also, note that my wells were rather large to be used as wet storage for anchor and line, or even to keep canteen cool. Also, I could put a paddling seat on top of one of the wells: no wasted space! But the wells can indeed be made very small, just large enough to get your hand/wrench in to tighten the module bolts. Also, you can fill a large well with foam flotation, and then you have option to make well a wet storage and a support for a paddling seat, etc. Look at a top-down photo of my old proa in the "proa comparison" photo, which I think I posted at wtarzia(dot)com on the photos page. I say 'think' because I had some trouble updating my site and I now have to check if the changes went through. I can just e-mail the photo though if you send private e-mail address to wtarzia at nvcc dot commnet dot edu.
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