Transom Question

[Rodnator]

Hello all. I am about to build a new transom for my 21' I/O with a 5.7l mercruiser/alpha 1 sterndrive. It appears that the old transom was 2 pieces of 5/8" with CSM in between. The fiberglass at the transom is exactly 1/2" thick.The plywood before destruction measured exactly 1.5". I have 1708, 18oz, and 24 oz roving availiable to me. I am wondering, between plywood, the thickness of the glass lamination, and bonding to the existing transom what would be the best use of materials. I have both 3/4" and 5/8" plywood to choose from. I guess the maximum thickness for the drive is 2 1/8" I am using west system epoxy if it is relevant. Any advice would be appreciated. Thanks in advance.

 

[thrillhouse700]

Re: Transom Question

Check the manual for the engine and drive combination that you have. These are located in the sticky of the engine forum. Stern drives have a min and max thickness of the transom. When you build your transom use 2 pieces of 3/4" exterior grade ply. When we did ours we laminated it with one piece of 1.5 ounce csm. Then shaped it and encased it in fiberglass. Then we PL'ed it to the hull. We are still 3/16" too thin on ours so we are going to get a piece of aluminum plate to take up the difference.