Thread: hollow timber surfboard question (pix)

I will watch this thread with great interest. I have not even seen a hollow board built so will not offer any advice. I have sold strips to a number of people to build hollow boards and Kayaks. Most required planks 4.5mm 6mm thick and didn't appear to have the problems you are encountering. I felt they were attaching the planks one at a time directly to the framing. I the case of a hollow board the glassing, if specified in the design, was only on the outside.

i should include these shots of my last board so you can get an idea of what the finished product will / should look like....

Hello Shiftomatic,
I think the problem you have is due to the glass on the inner surface. To explain, to create the curve even a small one the wood must compress slightly on the inside of the curve. So because the glass and epoxy creates a tough/strong inner surface there is very little or no compression. Result the force must go somewhere hence splitting which starts on the outer surface.

An alternative is to epoxy inner surface to protect the wood (3 coats)
then glass the exterier for strength after it has been fitted.

A suggestion, post this thread in the Wooden Boat Forum here or ask a Mod to move it I'm sure there will be some help from those more qualified than I .

Good luck with it the board will look fantastic.

Cheers
Mike

Originally Posted by m2c1Iw

Hello Shiftomatic,
I think the problem you have is due to the glass on the inner surface. To explain, to create the curve even a small one the wood must compress slightly on the inside of the curve. So because the glass and epoxy creates a tough/strong inner surface there is very little or no compression. Result the force must go somewhere hence splitting which starts on the outer surface.

An alternative is to epoxy inner surface to protect the wood (3 coats)
then glass the exterier for strength.

A suggestion, post this thread in the Wooden Boat Forum here or ask a Mod to move it I'm sure there will be some help from those more qualified than I .

Good luck with it the board will look fantastic.

Cheers
Mike

thanks for that mike.
i was wondering if the glassing of the inside was the problem. what your saying makes good sence...

OK you have built boards previously glassing inner surface without problems? Wow it is a masterpiece.

Maybe this time there was a large change in humidity after you glassed the inside surface which caused the wood to expand.

Maybe!!!!

Mike

Top looking board

Originally Posted by m2c1Iw

OK you have built boards previously glassing inner surface without problems? Wow it is a masterpiece.

Maybe this time there was a large change in humidity after you glassed the inside surface which caused the wood to expand.

Maybe!!!!

Mike

mike,
i didnt glass the last board on the inside but after surfing it i notest cracks. so this time i thought glassing it on the inside would solve this problem.
also, the last board had half the rocker and half the roll through the ribs so bending the timber was no big deal...

Originally Posted by shiftomatic

mike,
i didnt glass the last board on the inside but after surfing it i notest cracks. so this time i thought glassing it on the inside would solve this problem.
also, the last board had half the rocker and half the roll through the ribs so bending the timber was no big deal...

Interesting, are you building to plans? The build method as Whitewood said is very similiar to strip plank kayak and canoe construction where the strips which are fairly narrow about 12- 19mm are glued onto moulds one by one often after beveling or cutting a cove in the join faces. The boards are then sanded and glassed on the outside only. Have a search in the boat building section.

Perhaps thats the answer in getting the curve without splitting.

Have you considered 3 or 4 mm marine ply as a substrate and veneer to get the great timber affect.

I will be interested in comments from others on this one as I am about to start a canoe with a curved deck and was thinking strip planked rather than ply.

Mike

Originally Posted by m2c1Iw

Interesting, are you building to plans? The build method as Whitewood said is very similiar to strip plank kayak and canoe construction where the strips which are fairly narrow about 12- 19mm are glued onto moulds one by one often after beveling or cutting a cove in the join faces. The boards are then sanded and glassed on the outside only. Have a search in the boat building section.

Perhaps thats the answer in getting the curve without splitting.

Have you considered 3 or 4 mm marine ply as a substrate and veneer to get the great timber affect.

I will be interested in comments from others on this one as I am about to start a canoe with a curved deck and was thinking strip planked rather than ply.

Mike

i think the difference between a kayak and a surfboard is you stand up and put your full weight on a surfboard's deck. where as on a kayak you dont. i think i need the glass on the inside to sandwich the timber.
i have thought about using ply then a veneer but i think its kind of cheating in a way.
people always say, "oh, is that just a veneer?"

As an officiendo of timber surfboards ( although I have not built a hollow board. I build solid timber chambered boards) & a qualified Carpenter/Joiner, I would steam & clamp bend all my timber planks to somewhere near the rocker shape for both bottom and deck before lam glassing the inner side of them ( the idea of laminating the inner side of both bottom & deck seems to me good for added strength & waterproofing) With planks for the deck as well as steam & clamp bending them to the rocker shape I would also plane a chamfer down the entire length of each plank edge so that the joint was as perfect & tight as possible as they roll down the ribs from centre to rails. All very tedious, tiresome work but the end result would be the payoff. Always good to have a couple of projects on the go at any one time. I am building a 6'4" fish & a 4'4" paipo (belly) board from recycled radiata pine & what used to be a mahogany school teachers desk at the moment. If I get bored with chambering the planks for the fish (chambering is also tedious) I go play with the paipo outline or fins!!! Have fun!!