Bolting to the transom

[Douglasdzaster]

Hello everyone. Looking for more advice from the wise here on my favorite forum.
The Monark I’ve been working on has a 40 hp Yamaha held on with clamps. I’m wanting it more secure and would like to put a couple of bolts. My question is what kind of bolts for the transom are best. I want strong but don’t want to start a reaction with the aluminum. I’ve never put a bolt through a transom before so any advice is greatly appreciated as usual. Thanks.

 

[maintenanceguy]

Stainless bolts will be fine.

 

[Douglasdzaster]

Wow! Thanks for the quick reply. I appreciate the input. I intend on using sealant as well.

 

[MrGiggles]

Stainless with nylocks is best. Make sure to lube them with grease or anti-sieze, stainless will gall, and no power tools. I also like to back them up with some very large, beefy SS fender washers. You can buy those on eBay.

Unless you have a right angle drill, you may find that the bolt holes are obstructed by the motor, preventing you from drilling with it installed. May need to mark them and remove the motor.

Use a good marine sealant that is safe for aluminum.

 

[Douglasdzaster]

Thank you sir. Sounds like a good reason to purchase a right angle drill. Lol I do have access to some extra long bits as well too.
I have some good marine anti seiz with no metal properties. I didn’t know that some marine sealants were bad for aluminum. I’ll be careful with that one. Thanks again.

 

[turbotodd]

yamaha supplies a kit that comes with all of the smaller motors. Really high quality bolts, washers, but they don't use nylock nuts. They use regular nuts, but then you have to double-nut them. Ain't going anywhere. Mind you I'm speaking of the BIA patterened motors (old style F25's, F40's etc). I can't see your pics but you may not have the BIA pattern on that 40.

Sometimes dealers will sell a jet motor, which is a short shaft outboard with no lower unit-and the jet foot comes in a separate box. In the jet box, there is a second set of mounting bolts for the motor. So, with all that said, you might check with a dealer and see if they have an extra set laying around that they aren't using.