My beautiful boat has transom rot

3 Years ago, I replaced the rotten plywood transom boards with 3/4 inch pine board as I thought it wouldn't rot. Today I went out to run the 55 Evinrude and get ready to take the boat out. That's when I discovered that the board inside had rotted to the point it was crumbling. I varnished and painted it over the years so I thought it would last. After reading other transom posts on here, I know not to use plywood but are pine boards no good too? Would oak be better? The funny thing is that the wood on the outside that the O/B rests on is still hard. The wood transom has a metal plate over the top that mates with the outboard securing plate over the wood. Did I trap the moisture in?

By all means use plywood, but NOT pressure-treated plywood!

Look up the 16 foot Sea Nymph in my signature (#3), as it has a new transom, 2 pieces of plywood epoxied. It is still going strong with zero rot and used in salt water, attached with stainless steel hardware (properly insulated from the tin).

Thats a real nice job but my boat has reinforcement piece going from the hull to the transom. So i am limited to a piece maximum of 7 1/2 inches deep. still hoping to use one piece of 3/4 inch cedar

1960 yellowboat said:

Thats a real nice job but my boat has reinforcement piece going from the hull to the transom. So i am limited to a piece maximum of 7 1/2 inches deep. still hoping to use one piece of 3/4 inch cedar

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There is another active thread here on this same subject.

I would think the pine wood available these days has little to no rot resistance.

You can cut plywood to any size you want. I can understand why you might not want to waste an entire sheet of plywood for a 7.5" piece. Every home improvement store I've been to has a bin of cut down sheets for sale. Check to see if they have B-CX in the thickness you want.

I personally would opt for exterior plywood, but if for whatever reason you want to use solid wood, I would pick white oak over cedar. Whatever you use, seal the heck out of it.

3/4" Exterior grade CDX is $37.95 at Lowes here in the Northeast. I know, I just went through 3 sheets of it in my boat re-decking project.