Interesting question. I would think if the wood has been sufficiently dried and you coated it fully with epoxy (top, bottom and sides) that the piece would be stable for a long time.

Saturating solid timbers with epoxy will reduce the movement but not eliminate it. Depending on how wide and thick the plank is also a factor. I have had a solid 3/4 " deck of mahagony split open with movement after thinking epoxy would seal it. Don't get rid of the plywood deck. Mill your pine to an 1/8" - 1/4" thickness and cover the plywood with them. If you want thicker planks without ply backing I've had good luck using 3/4 X 3/4 strips edgenailed or glued. Will still move around a bit though - but not much. Wooden Boat Magazine recently had an article on decks.

Recently built a Wherry.  This boat design is tight- once you've got the boat built there seems to be essentially no flex or twisting action under the normal forces during use.  I suppose you could invent a machine to torque it, or just drop it from a cliff or something like that.  Otherwise I don't think you are going to see the forces that would crack that wood- unless you made it just too thin.

I like Roberts idea of essentially using the Tasmanian Pine as a veneer over the ply, though.

Hickory

Plus one for the veneer idea.  A sheet of solid King Billy (particularly one that is thin enough not to cause a weight penalty) would very likely buckle/crack etc sooner or later.

I put veneers of book-matched Tasmanian Sassafras on my Sassafras 16 decks (and recessed the decks into the inwales to hide the ply lines.  It looks great (humility isn't my strong point :)), and is dimensionally stable.

Love that Sassafras veneer job.

Hickory

Thanks to one and all.  Very interesting thread.  I have decided to use the ply supplied for the fore and aft decks with the possibilty of fitting some veneer on top if I feel inspired to do so.  

Was there a photo of the sassafrass veneer job supplied by David Warren?  If so I was unable to see it.  I was in Tassie recently and tried to get my hands on some purple-hearted sassafrass but was unsuccessful.  Very sad. Beautiful timber.

Scott

Hi Scott. Not sure why you can't see the pic. Here's a link to the source picture: http://img.photobucket.com/albums/v160/Davdoodles/CanoeLaunchDay1-1.jpg 

If that doesn't work, send me an e-mail address and I'll send you a .jpeg...

It's an awesome wood - distinct stripes from black to almost white, and rich ambers and browns between. Mmmm, shiney!

Hi David,

Your deck looks stunning.  I've had the pleasure of working with sassafrass in the past and was hoping to source some for the future while on holiday in Tasmania last year.  The wonderful colour is a result of spalting and other fungal defects, but there's no way of knowing what is inside before you fell the tree.  Quite often a tree is brought down and when milled the damage (from rot, spalting, etc.) is so extensive that the tree is virtually worthless.  Not very cost effective and too risky so they're not  felling very much.  Maybe the Tasmanians just want to keep it all for themselves (who could blame them?).

I love the way CLC builders take a great boat  and customize it to personal tastes.  Well done.