Originally Posted by Gray
Could it be that the gel coat has cracked and water has managed to seep into the wood structure under the glass.
I can't think of any other explanation. You're always going to get water in the boat... rain, spray, so the fact that the boat recently filled with water is only one of many instances of when there will be water on the deck.
Ben - bear in mind that it's not just the static weight of the new engines that would be important - the pushing/twisting force on the transom (effectively pulling the top of the transom outwards) would be greater with any increase in power.