Transom motor mounting

[jerry123]

I have a 17 ft. Deep v aluminum hull bluefin sportsman that i removed a 1989 merc. 80 hp with power trim. My question is does anyone know if a 90 hp yamaha with power trim would have the same mouting holes ? Transom seems strong but i picked up 2 peices of 1/16 stainless plate to mount on both sides. Good idea ? And whats the proper 3m type caulk?

 

[Chris1956]

Re: Transom motor mounting

The standard bolt pattern is four 1/2 fine thread bolts. If the Merc has this, it will very likely interchange with theYammie.

I use any silicone caulk

 

[j_martin]

Re: Transom motor mounting

The standard bolt pattern is four 1/2 fine thread bolts. If the Merc has this, it will very likely interchange with theYammie.

I use any silicone caulk

Bolt pattern should be industry standard for both.

Do Not use silicone. Silicone (Bath tub) caulk is the reason most transoms from the 70's and 80's failed, including mine. Use 3M 4200 marine sealant instead.

While the bolt holes are open, poke around to see if the wood is rotten at the holes. That's the first early warning of transom failure.

Fine and course bolt threads don't make any difference either. You can't fully torque a fine thread bolt without crushing a normal transom anyway. Use stainless bolts, and wax the threads when you put on the nuts. An old candle, furniture wax, or anything else wax laying around will work fine.

 

[jerry123]

Re: Transom motor mounting

thank you jerry123