Davit mounts for 77 Seacraft 20MA

[Capt Terry]

Hey Mitch- You are quick, before I could retrieve this Bushwacker post from 2007, you had responded.

On my '76 Seafari I have removed the transom u-bolts probably three times to examine and have replaced at least one due to corrosion. They are difficult to remove and found a slide hammer (a weight that slides on a bar with a hook attached at one end) worked well. I also found the "legs" of the u-bolts (even new) were sometimes not parallel and used a pistol grip clamp to improve parallelism initially to get them back in the holes.

From Bushwacker in 2007
Gillie's right - crevice corrosion is a very common failure mechanism for those transom eyes. Anytime you see rust streaks from them, that's what's going on. Stainless has to be exposed to oxygen to maintain the protective oxide layer to remain "stainless". When it's buried in a thick transom away from the air but not sealed well enough to keep moisture away from it, that's the perfect environment for crevice corrosion. Silicon bronze doesn't have crevice corrosion problems and is often used for marine fasteners and sea cocks for that reason, but I haven't seen any u-bolts made out of it, maybe because they wouldn't have the strength of SS. Monel is a very corrosion resistant (and expensive!) nickle alloy sometimes used for prop shafts. A friend of mine that bought a Moesly 21 new in 1965 replaced the threaded rod attached to the bow lifting eye with a Monel rod on his boat because he kept it on davits and was worried about corrosion.

Best bet if you redo the transom is to seal the towing eyes with 5200 or a good polysulfide caulk such as Life Caulk that remains flexible. Drilling the holes oversize, filling with thickened epoxy, and then redrilling to size would also help by keeping moisture-retaining wood away from the stainless material.
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