Best material for kayak/canoe

[joebagodonuts]

Alright so I have the plans drawn up and have built a 1/3 scale model for my boat out of cardboard. So far I like the overall design and shape so now I can get on with the build. It'll be about 10' long with around a 30" beam. This is where the questions start...

I've never dealt with fiberglass before or built a boat, but that doesn't worry me too much. My plan is to stitch it with zip-ties, glass just the seams on the inside and epoxy the rest, then cover the entire outside hull in a sheet of fiberglass. All I need to find is a cheap, flexible material to make it out of. I was planning on using thin plywood. Does this sound good?

Thanks so much for the help...

[Fanie]

The best would probably be to make a mould for it. Since it's a small boat, you could even make a clay form and glass that over. If you do it like this you could cover the wet clay with wrap and glass over that, then remove the clay before it is dry which could take a few days.

The wood in the canoe may not be the ideal thing, you can just as well just use fiberglass to save weight and add a bit of glassed in closed cell foam to maintain buoyancy.

[joebagodonuts]

I've thought of the foam and glass method but isn't the foam pretty expensive? Thanks for the help.

[Fanie]

Doesn't have to be... If you go to the manuf or a user then you may be able to scrounge some offcut pieces, you can glue together, then file/saw/grind/cut to fit in where you want it to be. I prefer to use a 35kg/m^2 PE foam... light and doesn't absorb water. Glass in place and you have proper long term buoyancy. It could be too little, but never too much. Fill unused spaces works best.

Good luck with the build !

[ondarvr]

What type kayak are you going to make, or what do you plan on using it for? This will make a big difference in what size it should be and what it should be made from.

[joebagodonuts]

I'll probably mainly be fishing from it and just cruising around with just me and not a lot of gear. If I can get a hold of a camera I'll try to take some pictures of the model I made. It's nothing exciting, just a little summer project to keep me busy.

Thanks

[ondarvr]

Normal fiberglass will be fine for this type of Kayak. Most aren't cored with foam and have a thin laminate, they do use blocks of foam inside for floatation and support though. You can make a one off mold from plaster for a low cost and it's faily easy to work with.

[joebagodonuts]

Thanks for the help! So the stitch and fiberglass method should work? I assume you leave the zip-ties in until the fiberglass has set and then you cut them out.

[ondarvr]

I think I would skip the stitch and glue method and make some kind of a low cost, one off mold. Fiberglass kayaks are thin and light, with S/G you may end up with something much heavier than it needs to be.

[joebagodonuts]

Thanks a lot ondarvr! Would it work to make a S/G kayak and then use that as my mold? I was thinking I could make the S/G and then cover it with the wax and release agent and stuff.

I guess I need to research how to make and use a mold. I'd never thought of doing it that way till now. Thanks

Edit: I looked around the site and I guess I could make a mold out of super thin plywood and then cover it in a sort of plastic and then a 'quick release' agent? Sorry for all the questions, I feel like my brains about to explode with all the different ways I could do it. All of them are new to me....

[Petros]

The lowest cost way to test a hull design is to built your intended hull design in what is called "skin on frame". This is actually the ancient and traditional way kayaks were built by native builders, it uses very few materials, is light and comes together faster than other methods.

You built a frame from plywood ribs or frames with wood stringers that is lashed together. If you build a "quick and dirty" frame from scrap wood, you can wrap it with plastic sheet and tape, then go out and try it out. It takes only a few hours of work. Then if you like the design you can build one by stitch-and-glue and fiberglass.

IF you use better quality materials and more durable lashings the skin-on-frame method makes perfectly good kayaks. You seal the wood frame with marine finish, cover it with 10 oz nylon or polyester cloth and seal it with polyurethane finish to make a pretty durable and light kayak. I have built 8 boats this way using salvaged lumber and most only cost $40-60 to build. Most weight about 20 to 35 lbs and about 80 hours to build including ripping and planing the lumber. Do a Google search for "building skin on frame kayaks" you will find lots of hobby sites with instructions and suggestions.

This kayak I built for my wife. It is made of cedar stringers, steam bent ribs, lashed frame, with 9 oz nylon skin and polyurethane sealant. The complete kayak only weighs 18 pounds. It is about 15 ft LOA,




Here is how the frame comes together, this is the frame for a 14 ft sailboat I built using the same method. A kayak would be much simpler with fewer parts. In this case I lashed the ribs and stringers, and used screws on the frames. It uses steam bent oak ribs with doug fir stringers (all salvaged lumber), heavy plastic "skin" and a Tyvek sail to test float it. The finished hull cost less than $35.

[ondarvr]

That looks nice, light too. I was only into making all glass kayaks and I could whip one out fairly fast, even a one off design. I never had the patients to do a lot of wood working.

[rwatson]

Your best bet is to get some smooth surfaced bench space (lay plastic over an old door frame) and make 1/4" fibreglass flat panels.

Either pour them in the correct shapes, or cut the shapes out with a saw, and stitch them together with copper wire, and tape the edges.

you can use a design for any small stitch and glue canoe plans.

I dont think its a better way than plywood - weight for stiffness, 1/8 plywood is a far better and cheaper option.

[joebagodonuts]

Thanks so much guys! Makes me want to be a boa tbuilder so I can try all these ways out.

[joebagodonuts]

Alright another question: what's the best to use to hold the seams together, fiberglass cloth or fiberglass mat? I would assume the cloth since that's what I've seen everywhere else. Any advantages to either? Thanks again I'm getting closer!