Securing my outboard to an insecure transom

[checkeredflags]

I have an old (1974) 16" aluminum boat and my 25 HP mercury is bolted into the wood transon. Because of its age, there is a risk of thre trasnsome giving away as the engine (25 horse engine mercury 180 pounds) is placing a great deal of strain on it. I want to to drill two additional holes through the thin aluminum below the wood transom 1/2 " in diameter in order that I can install two extra bolts in the engines mounting bracket. There are two bolts going through the transom above the water line that go through the wood; however I need additional reinforcement and this will require that I drill two holes through the thin aluminum below the wood transom to bolt the lower portion of the engine mounting bracket. I thought I would use a thin steel plate on the inside of the haul and drill two holes (1/2 " dia) through the thin aluminum haul below the wooden transom. I'll then run 1/2" bolts through the aluminum and the reiforcement plates and bolt it down. My concern is leakage since this will be right at or below the water line...not sure what to do. Is this practical and if so what type of sealant should I use to prevent leakage......Pleasae help as I do not want to loose my engine

 

[JB]

Re: Securing my outboard to an insecure transom

Your other post is in the correct place, CF. Duplicates are not welcome.