Chesapeake 17 & marine ply ...advice please

Hi all, Please note that i live in Scotland. I'm an experienced woodworker, but first time boat builder. I've bought the plans for the Chesapeake with the intention of starting construction shortly. Unfortunately i've encountered a problem - i can get marine grade ply ok, but the smallest thickness is 6mm. I can't find anyone within driving distance who can supply smaller and having it delivered would double the construction costs of the yak. Question - can i get away with building the boat completely in 6mm or should i use thin exterior grade ply for the deck? Thanks, Marc

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RE: Chesapeake 17 & marine ply ...advice please

G'day from sunny Australia, Marc.   Having built a Chesapeake 17LT earlier this year I feel qualified to answer this, so here goes - you should re-double your efforts to obtain 4mm marine ply for the hull and 3mm for the deck.   Try the internet, kayak clubs and their members, etc., for info on sources.

If you build out of 6mm several things will happen: you may find difficulties with the ply taking up the correct shape of the hull, especially at the ends: you will NEVER get the 6mm to take up the heavy camber of the deck in front of the cockpit: and above all it will weigh a ton.   Over and above all this, I think it would spoil the building experience for you, depriving you maybe of the joys of going on later to build other designs (the Chesapeake is a fine first choice).

If worst comes to worst, I'd be inclined to use carefully chosen exterior grade for both hull and deck, if you can get 4mm and 3mm respectively.   At a pinch, 4mm for both would be OK, but it's a bit of a test of brute strength getting the deck ply to conform to the camber, despite the fact that 4mm is the recommended deck material.   Most Chesapeake builders use 3mm for the deck - I did.

I know of many builders here who use exterior ply for S&G designs for many reasons - availability and cost being among them, and often they seem to be able to achieve a nice clear varnish finish anyway.   If not, a paint job can often look just as nice on the hull with varnish on the deck (that was my choice, even with marine ply all round). 

An alternative suggests itself since you are apparently an experienced woodworker - if after all attempts you cannot get the preferred marine ply, why not think about a strip-plank build?   Usually I'd suggest first-time builders should get their hand in first with a stitch-and-glue craft, but your case seems a little different.   It comes down to your confidence in your own abilities, I guess.

But stay away from that all-6mm barge!

Keep us posted, won't you?



RE: Chesapeake 17 & marine ply ...advice please

Weight aside... you can bend ply wood.  Here is a picture of my SOF where I used 6mm for the coaming, steamed it and bent it.  The cockpit bend was actually done courtesy low pressure weather system that brought high humidity.  This bend is much more tight than the deck C17.  Since it will be impractical to build a steam box to hold that, you can always pour boiling water over the wood as you work it.  It will be tough and the flexibility is as much the type of ply as the thickness.  I have two pieces of 6mm, one Meranti and Okoume, the Okoume is 100% more flexible but more so on it’s with and not it’s length.  Go to the yard and have a look at the ply they are selling, check out its flexibility.

Coaming using 6mm

As for the weight, I googled and found that the weight is about 50% greater… kinda makes sence since 4-6 is 50% thicker… big question is how much of the boat’s weight is wood… let’s assume that you end up overall 50% greater, then the 17 goes from a 45lb light weight to a 67.5lb middle weight.  Is that a weight you are prepared to live with?  More importantly, is that a weight you are prepared to hoist up on top of your car every time you want to go for a paddle?  I am really appreciating my 30lb SOF yak every time I go for a solo paddle.  The C18  (once she's done) I think I will save for when there will be a helping hand available.

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