Outboard mounting bolts

[Captain PartyMarty]

hey guys

I am starting to think about mounting my new motor and notice that the old bolts seem a little odd. They are 1/2 in fine threaded stainless bolts with brass lock nuts. If the fine thread standard practice? And what about the brass nuts? I want to replace them, but do I stay with brass or go to stainless.

 

[wolf]

Use stainless way stronger then brass with BIG fender washers and lock washers and re torgue after a few trips, as for fine or course thread dont think it matters much

 

[1marko]

fine threads hold better in extreme
vibration applications. either way
you would want to check periodically.
if you find they are loose but have not
backed off there could be transom issues.

 

[Captain PartyMarty]

Thanks guys the brass nut had me confused. Going to replace with stainless

 

[noluck]

remember to lube the threads when stainless to stainless, or you will gall the threads

 

[Canso]

They are probably Bronze nuts, which is compatible with stainless, and prevent thread galling.

Like noluck said, lube the threads you should be fine with stainless.

 

[TheBigGuy]

If you think the transom could be getting soft because water was entering through the loosened bolt add a backing plate of starboard and just use some longer bolts. Seal it all up with a goodly amount of Silkaflex. My transom is aluminum in my boat and obviously won't rot, but I added a backing plate this summer when I changed my bolts. I just figured if I'm swapping out the bolts anyways it's always nice to strengthen up an important area like the transom. Starboard won't rot, and on an aluminum boat it's always good practice to insulate dissimilar metals like stainless bolts and screws from the aluminum hull.

 

[windsurfer]

The problem with stainless nuts on stainless bolts is that they frequently do gall. If that happens the nut will not come off and you have to cut or break the bolt off. That's not really a problem though if you have easy access.

 

[Reel Gone]

You want to stay with fine thread as mentioned they hold much better in vibration ares. Definitely bronze nuts that you were looking at, if you want to be able to remove them again it's a good idea to go bronze, if not stainless will be just fine.