Having successfully removed four of the eight keel bolts
on my 1978 Pearson
26, I am ready to replace them. See my other post about it if you like: Replacing Keel Bolts, One at a Time
One of the old bolts was being eaten away by water
intrusion, but three out of the four looked very good. I'm leaving the other four in since after all this I'm confident they look good as well.
On the P26 fan site, they have a link to a black alloy steel
bolt as a suitable replacement on the McMaster Carr website (I bought one, see picture). Although this bolt is the perfect shape, it is not high strength steel
and has no resistance to corrosion
, so I'm not sure it's the best choice. I can get a Grade-8 Steel bolt with a salt water
galvanized coating on it, but only in a hex head
, which would not spread the load out as smoothly as the beveled heads on the original bolts.
I have read that stainless steel bolts are out of the question with a cast iron keel
, since they can suffer catastrophic pitting when deprived of oxygen and since SS can react galvanically with the cast iron. I'm assuming this is true, even though people still keep suggesting stainless to me.
Having shopped around at a number of companies, the best thing I can find with the same dimensions is a Grade-8 Zinc plated bolt. Nobody seems to make it in galvanized, which is what the old one looks to be. (See picture) I'm thinking of putting a little anti-seize under the beveled head
so that it doesn't bond with the cast iron, using life-calk to waterproof from under the head up the shaft of the bolt and under the washer, then capping the exposed bolt end and nut with epoxy
on top. I'll epoxy
over the top of the bolt in the keel
recess and fill the recess with faring compound, then epoxy over that again to keep the water
So, is this Zinc-plated Grade-8 Steel bolt going to be an acceptable substitute? I'm hopeful that I can keep the new ones as dry as they have been for the last 25 years, but I would hate to replace them with inferior metal and have four rusty bolts a year after I'm done with this.