Unless you have to hollow out the interior faces to insert some kind of hardware, like nuts, bolts, ballast, etc., it's always better to use the single full thickness instead of laminating two half-thickness sheets. The plywood manufacturers have much better bonding equipment than amateur boat builders. Their interior joints use wonderfully strong toxic glues bonded under high heat and tremendous pressure, things that you can't do at home. The glue lines are even and the grain alternation is continuous. The resulting piece of wood is much stronger than one you laminate yourself.

Reasons to laminate your own, besides needing to put something inside, are mostly economic. Buying and shipping one small piece of double thick wood can be a lot more expensive than laminating a spare piece from a sheet that you have to buy anyway. If the use can handle the lower strength of a home laminate, it could be worth it to do it yourself.

Laszlo

Mike,

Congratulations on starting your build.  You may be able to use the 3/4 ", but there is a little lip/ rabbet on the inside of each of the 2 pieces in the kit. When you put the 2 pieces together it creates a place for the lead to go in when you pour. It is there to hold the lead in. You would probably need to come up with an alternative for that. 

Also,I invite you over to the PocketShip.net forum. There are a few active builders including me and former ones that frequently post. 
thanks

Ron
 

   Great,

Thanks for the info.  I have a router bit meant for biscuits that will work well to make the recess for the lead pour.  Looking at the forum, there was some discussion about the original kit size of the opening being too small to hold the recommended weight.  I'll have to look into that.

Mark

So at 3/4 thick.  9KG = 20lbs.  I get 64 square inches for the opening at .41 lbs/cubic in   

>>>>So I'm finally working on my Pocketship kit.  I need to start over with the centerboard. Do I have to laminate 2 3/8" layers or can I just use 3/4" plywood?>>>>>

I'd rather you laminated two 3/8" layers to create a 3/4" centerboard.

Assuming you're using marine plywood, you'll end up with 14 veneers in the finished board instead of 9, so the board will be QUITE a lot stronger.

A single layer of 3/4" plywood also has much more danger of warping. If you glue two layers together on a flat surface, any warping forces tend to cancel each other out.

John,

Thanks, will do... just changed my plywood order at home depot :)   I built the keel 4 years ago.  It took quarantine to keep me home enough to get this going again.