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How thick is the okoume plywood you used to build your spindrift ?


Captain Tim

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I have the plans to build a Spindrift 11' and have started to source the plywood. One supplier lists 6mm weighing 18 lbs. 7mm weighing 21 lbs. Alan at B & B told me okoume plywood weighs  .1lbs per mm per sq. ft.. This would mean 6mm should weigh 19.2 lbs. So the 18 lb sheet would be

5.625 mm and 21lb sheet would be 6.562. I'm thinking the lighter ply would be the right choice as long as it is strong enough.

So the question is, How thick is the okoume plywood you used to build your spindrift ?

 
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Kennneee thanks for the reply.

How long ago did you build the spindrift 9' ? Is it nesting ? Sailing ? Do you feel the bottom is strong enough to stand in ? Any oil canning when under way ? How light were you able to make her ? 4mm seams a little thin to me.

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Tim-Graham tweaked the Spindrift design slightly for me to optimize it for rowing. I don’t plan to sail it so it was simplified a bit. We started calling it the “Kendrift” to differentiate from the standard design. It is not a nesting dinghy and there is no hint of oil canning or any other weakness. I stand in it all of the time. There is plenty of structural members such as seats that add stiffness. She came out around 66 pounds before I added oar locks and fendering, etc. She rows beautifully. Recently bought a EPropulsion electric outboard for her.

Here is a link with more info:

 

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Tim,

 

You just need 6mm okume ply for the S11n.

 

Tom came up with the 1# per mm per sq. ft. rule. It is handy when we are roughing out a new design for estimating the weight. We have weighed a lot of ply over the years and it will vary from batch to batch, not to mention different species.

 

I have never seen 7 mm okume ply. We used to be able to buy 5/16" back in the day. You would not be able to fold a 7mm Spindrift into shape and 4mm would not be stiff enough for the bottom, as you had surmised.

 

We had an issue folding Spindrifts into shape when I was teaching boatbuilding at the local community college. The bow would sometimes crack, even days after it was folded, whereas it never happened at our shop. We realized that the CC shop was air conditioned and heated and was a low humidity climate. This dried out the ply making it very stiff. We started wetting the forward bottom panels before folding and eliminated the problem. If you are lucky enough to be building in a climate controlled environment or you live in the desert I strongly recommend wetting the bow areas before folding.

 

We live in a high humidity environment. Occasionally it will be so damp, it feels like you can drink the air. We have had an offcut of okume ply which was so limp that we have tied it into a knot. The same piece a week later would have broken.

 

Good luck with the build.

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Hope I'm correct in thinking Designer = Graham.

Graham thanks for your input. The reason I started this subject is I have not heard of 7mm plywood either. I plan to go see the plywood first to make sure it is the real deal (okoume) before

I buy any.

I'm in New Hampshire so it does get humid but right now it is cold so progress is a little slow.

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