It's only a bumper David. The stainless bolts will be going into plain steel threadsh. I can't see any reason at all not to use stainless in this situation.

Mr Fenner wouldn't like the offshore weather buoys I'm helping to make - aluminum with 316 stainless fasteners :)

alistair

On 2013-08-01, at 1:31 PM, David Beierl wrote:

> At 04:09 PM 8/1/2013, Alistair Bell wrote:
>> Probably ss fasteners if only just to bug David B. who will point out the electrolysis problem between stainless and aluminum :)
> 
> I'll just point out that if you do you'll save yourself grief and broken bolts when removing (or burst fittings down the line in the case of for example a cleat) if you make your holes generously oversize.  Our main halyard cleat on Scamp (mounted with 3/8" bolts, I think) split right across one of the two mounting holes because the white corrosion products built up between the bolt and the hole in the cleat.  I wasn't there when it happened but I'm told it made quite a bang.
> 
> Wisdom from Keith Fenner, a marine shafting specialist and machinist on Cape Cod (he's got good stuff on YouTube) is do not use s/s fasteners when working with aluminum, use steel instead - at sea or on shore.
> 
> My other bad experiences have been twisting off s/s bolts threaded into aluminum, again because of prominent buildup of white corrosion products jamming the hole.  So I'm inclined to go along with Mr. Fenner at this point.
> 
> Yours,
> David