JEM Watercraft

Before you go to far you might want to go to Sparkys forum and read are we building our boats inside out.
Ron
http://www.neilbank.com/phpBB2/viewtopi ... +backwards

While it's obviously possible to build a boat of glassed balsa, practicality is another question. It is difficult to match the strength that plywood brings to the game. Pretending that the inner core between glass layers can be a soft, weak, or spongy material may sound intuitively appealing, but I wouldn't risk anything important on it. Like, my Life.

Even cedar strip boats go to a thicker material than 1/8" or 4mm plywood. It simply is not as strong as plywood.

jlparsons wrote:I've thunk on this all morning and the decisive question is this - how thick a covering of glass is required over balsa before it's puncture resistance becomes acceptable?

Jack brought up a thought , when I was a kid I made model airplanes and the Ambroid Glue sure soaked into the wood and made a tight / Strong bond. Those plains did handle some ungraceful landings at times.

Thinking about the glue , if a person was to epoxy saturate the balsa that would make it less spongy and a lot more solid , epoxy does get hard when it cures , then glass the boat for additional strength. The wood should be epoxy saturated so there is a good bas for the glass and epoxy to bond with. Might say , killing two birds with one stone by doing that.

Between the two ... the epoxy saturation and then the glass it should be rather puncture proof , not bullet proof.

Chuck.

I think you're correct, Chuck, in saying that epoxy saturating balsa would strengthen it. A guy, or gal would have to experiment to find out about how much weight of epoxy it would require to get, say, a 1/8" or 3/16" thick strip of balsa to equal the puncture resistance of plywood. There would be a strength to weight ratio here.

I wonder if it's even possible, no matter how much epoxy is soaked into a strip of balsa, to get it to equal the strength of epoxy saturated plywood? Recognizing that most plywoods would not soak up as much epoxy as would balsa, those cross plies add a lot of strength.

Another thought occurred to me - there's no reason why you couldn't hybridise to make weight savings but keep impact resistance where it's needed. Looking at the weights people have achieved, I'd say it'd be possible to shave quite a few pounds off the sabalo just by replacing internal and upper panels with balsa core. You could then do the main hull and cockpit bottom in plywood as normal, or be adventurous with balsa and kevlar if you want to go nuts.

I'm happy that balsa core will be very strong and stiff, so using it in places that aren't going to get thumped looks like a good idea?

Also, for panels which don't need to be bent like the internal structures and top panels for the sabalo, you can buy pre-laminated balsa/glass panels. This would cut working time too, and eliminate some of the uncertainty of working with a new material.

With the amount of rosin and glass you are going to have to apply to the balsam I would just about take the bet that 4 mm ply will be just as light at the same strength.
The way I use a boat the balsam would be firewood in a short period of time, also where you step in and out of a boat catches a lot of stress.
Personal opion here but I think you are trying to reinvent the wheel.
I have been known to get outside the box a few times myself
so have fun with it.
Ron

Ron...

You just don't get outside the box , you get way away from it. I could say you are in Texas and your box is in Alaska. But I will be nice and not say it.

Chuck.

Box? What box? Nobody ever told me about any box?