I want to build a skin-on-frame kayak (pic related), and I'm looking for a suitable (and cheap) material to build the frames.
Usually, marine plywood is used for this. However, this is not locally available, and shipping cost would almost double the price, which is just ridiculous.
So I'm looking for a suitable alternative (if there is one).
One thing I have tried, I kid you not: I glued together three scrap pieces of high density fiberboard to the desired thickness, made a frame from that and tested how strong it was. I put it on two pieces of lumber and jumped around on it. To my surprise, it hardly budged. Now this would be an incredibly cheap way to do this, and it seems to work well enough (I'd have to seal it somehow, I guess), but it also is an incredibly stupid way to do it.
Any suggestions welcome.
>>993815
>high density fiberboard
i'd love to see how this swells when it gets wet
maybe you can treat it with epoxy, or soak it with polyurethane?
>>993818
Yes, I'm aware of that. However, the process of gluing those pieces of HDF together was just some wild experiment I did because there was nothing else around. It's highly unpractical.
I'm interested in alternatives that come in the desired thickness (1/2 inch) and are comparable in strength to marine ply. Water resistance isn't really an issue since I can just treat it, like you suggested.
>>993825
Can you just use regular plywood but seal it ?
>>993831
As I understand it, the advantage of marine ply is that there's no gaps in between. I could go out and try my luck, but it's a gamble and I'm unsure on how this would affect it's strength.
What about OSB? I get mixed opinions on google. Some pages say that it's equal in strength to plywood (while heavier), others say that plywood is stronger. If they're indeed comparable, I wouldn't have to worry about voids/gaps from regular play.
Also, my apologies for knowing jack shit about such things, my questions may sound silly.
>>993815
Its your lucky day op. Boat Wright here! First of all. Do you ATLEAST. have a tablesaw/power drill?
>>993815
Why can't you use real wood? I know you can't make the frames in your pic out of once piece and have the same strength like you can with plywood but you can make it work. I'd make it out of overlapping pieces so every joint fell in between the runs of every other piece. Pic related, black marks being were the joints are. Glue and screw the fucker together and it wont go anywhere. Since real wood is lighter than plywood you would probably end up with something only slightly heavier than something made with marine grade plywood.
>>993815
Pressure treated plywood may be available. That and spar varnish. Prepare to refinish every couple years minimum.
It will work, but more than likely won't last as long.
Also, check Google for plywood distributors and hardwood dealers. Hardwood dealers sometimes have marine ply if they also carry hardwood plywoods.
>>993835
As I understand it, the difference between marin plywood and normal plywood is the voids. In marin plywood, there is none. In regular plywood, small voids are left there, larger ones are patched up. Those voids and patches become ideal host sites for fungus.
Long and shot being you can build a boat with regular plywood, it just won't last as long. In the case of a kayak, which will spend most of its life out of water, this isn't as important.
Ground contact plywood is cheaper than marine grade but still expensive. I'm reasonably certain that a marine grade urethane applied excessively would seal it well enough to work for this since a kayak isn't in constant contact with water like large boats docked in the water are.
ok, first off, you can use exterior grade ply just fine, Cheap ply if you seal it well. Also, this isnt the only way to make skin on frame, the more traditional approach can be made with most regular woods.
http://www.instructables.com/id/Build-a-Greenland-Kayak-8/ <- Traditional method.
Cedar doesn't rot. Try it. Anyone that sells fencing materials should cell Cedar of some sort.
... PVC?.
>>994906
Pvc is too brittle to actually be used for more then a year. And op is kill.. Been waiting for his reply for a few days now.
aluminum tubing
use this as an opportunity to learn to TIG weld.
>>994908
We have used PVC in cheap seaside beach furniture and they hold up for decades of 300 lbs tourists.
Maybe all the sunscreen they leak helps.
>>994914
kek'd
As long as you're willing to accept that your kayak won't last forever, just use whatever ply you can get your hands on. Failing that, getting the marine ply shipped is still most likely cheaper than any reasonable alternative.
>>994914
http://www.amazon.com/dp/0896960870/
kek
How cheap does marine plywood have to be?
http://www.ebay.co.uk/itm/Marine-Plywood-BS1088-Top-Quality-Marine-Grade-Exterior-Plywood-Sheets-/172004402117?var=&hash=item280c42e3c5:m:mCVim9EX9IXg6VnqsQ0NSBg
>>993815
Im trying to understand why it has to be plywood. Any number of solid woods would hold up just fine. Cut finger joints for any connections and your plain wood cross sections wil fail before the joint does.
>>993815
>So I'm looking for a suitable alternative (if there is one).
Heaps, I assume you're in Nth America
Get an axe and/or a saw, go murder the fuck out of some White Oak or Ash trees.
Chop them up to the desired sizes, make a steam bender and some jigs- bending it while its still a bit green will make it easier than kiln or air-dried timber too.
In a pinch and if you're asian, bamboo would work as well with a bit of treatment.
>Fibre glass
>Carbon fibre
>Kevlar
>>993815
Hi Anon, I use a nautiraid (check their website). They use polyethylene for the frames (only for aluminium tube versions). Pic related (not mine, but same model).
>>994852
This - seen shuttering play (lower grade than exterior ply but still quite weather proof) use for kayaks/canoes. Just seal the hell out of it.
Shuttering Ply should be cheap as chips and readily available since it is used by builders for casting concrete shapes, beams etc.
Exterior grade plywood is almost as waterproof as marine grade and is available pretty much everywhere. I've seen a lot of budget boat builders use it because it's cheaper too...
Furniture plywood is more expensive than marine plywood, buy it might be available locally. You can also salvage it from better cabinets if you're lucky. For stringers you can use chair legs and stuff like that.
Red Green taught me everything I needed to know about kayak construction!
>>994908
PVC is brittle because UV degrades it. Give it a good coat of paint and it will last forever.
Just get the best grade of plywood you can find/afford locally, and make sure to seal it well, especially the edges. It'll be fine and still last many years.
Or you can go full greenland kayak or whatever and not use any plywood instead creating the frame from steam bent slats.
>>997398
nope, disagree, I wouldn't trust most glues to hold in those conditions. The best construction method I've seen is mortise and tenon and lashing to reinforce. loose tenon or even dowels would probably work fine as well.
You just have to steam bend ribs instead of cutting them out of the plywood, basically.
>>993815
Go ask your local construction store, even if they don't have it, if they could order you some. They get it for under retail price + shipping and sell to you for retail price. So you won't get assfucked.
>>993815
Dude, you can structure pvc to be stable and provide a full frame. They make angled 4-joins for pvc to make it easy. You can seal it, get some inherent bouyancy out of the frame itself in case your skin is compromised, and everything else will be basically the same. If you want a little additional stability, you can just do a wood x-frame outlining the part right past your feet and right behind your seat, but otherwise it should be fine.
>>1001729
And be a laughing stock. Wood is what manly boats are made out of
http://yostwerks.org/
Any progress?
