Davit mounts for 77 Seacraft 20MA

[Mathertodd]

I am taking my Seacraft 20 ma down to the keys and will be keeping it on davits. What type of reinforcement will I need to the existing rear eye lifts? I will add on a lifting eye cleat on the stern. I assume I will need to put on a backing plate on the transom, but any suggests would be appreciated! Thanks in advance.

[DonV]

The transom U-bolts should be fine. Look at them from the inside (I have to remove the vents to see mine) make sure there is no rust around the threads and the nuts are very tight. The pop up bow eye pictured is a good idea and easy to install.

[77SceptreOB]

Yes, as Don says - inspect the rear U-bolts VERY carefully! I have broken 2 of them in the past due to rust. Both times under load. But luckily only one broke at a time and the other one held

[FLexpat]

If those stern eyes are reasonably new they are probably ok. If they are original - replace them. Where the eyes go through the transom there isn't any way for air to get in there and even though they are stainless, they are subject to corrosion cracking over time (years). Unless they are really bad, it is very difficult to tell by just looking at them until they fail. Both of mine were cracked and one was broken when I pulled them out; it took a magnifying glass to see some of the cracks on the 'less bad' one. They are relatively cheap and easy to replace.

[DonV]

Ditto on what Flexpat said! Most of the eyes are the 18/8 stainless or less and they will break. Peace of mind....just replace. Don't forget to lubricate the threads!!!!! SS never galls until you are in a tight, hard to get to place!

[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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[Mathertodd]

Thanks everyone. I will post some pictures of my boat as soon as it is down in the keys!