Transom help please.

[Karl]

My brother is working on a 1973 26' Tolly. It had twin omc's that were frozen, so he removed them and is adding twin merc cruisers.
Here are a couple of photos of the existing transom. It had some rot that he has taken out. He is planning on filling the holes and then adding an additional 3/4 ply to the interior side to get the total thickness up to approx 2 inches. His question is, will that be enough support for the merc I/o's? Any suggestions would be great.

[John Nelson]

Is there no way he can find a donor inboard boat and forget about the outdrive mess. He has to remove wood and fiber glass from the inside till he gets to a bare hull side to side, then install the new transom. Ask him how he plans on keeping water from soaking back into the plywood where the outdrives are. Consider using coosa board.

[Bflaherty]

Unfortunately the Tollycraft 26's were rarely set up as direct drive, there were a few that have V-Drives but to convert from I/O to V-Drive would require a lot of new/used parts and heavy structural modifications... Not to mention the extreme challenge of creating a perfectly aligned shaft log for two motors!!

I think the better route is to do what he is doing and convert to newer I/O models and just build the transom as strong as possible.. Like John alluded to, there must be special attention paid to sealing the cutouts so the new transom doesn't turn to mush... The Bayliner command bridge cruisers of similar size are notorious for soggy transoms cause the builders didn't understand how to seal the holes!