I hardly ever use 1/8" for anything structural. The alloy isn't a strength problem for your application. There's no place for any wood in a boat.
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I recently put a new transom and cabin on my son's boat. Coosa board is my go to for a transom, it's pretty much indestructible when you put fiberglass on both sides.

Last edited by TrueGrit; 05/11/21.

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