by GreenLake » Wed Aug 03, 2016 4:28 am
I had a single bolt bow eye on a '63 DS1. It came apart the second time I used the boat. Presumably after decades of service life. The fault was stress corrosion.
I replaced it like for like, and before long, the new bolt will have reached decades (plural) of service life...
On my DS, the fiberglass appears anything but a weak link. Particularly at the bow, the sharp angle stiffens it, and the laminate thickness is probably one of the highest anywhere on the hull. If you find a single-bolt eye loose in the hole, then the cause may indeed be a piece of wood backing suffering from dry rot. I don't recall such a thing from when I did my repair, but it's a long time ago by now.
Anyway, a better backing plate would be the answer.
The little plate shown for the U-bolt isn't substantial enough to really help prevent the fitting from tearing through the laminate. (Practical Sailor just had a review of backing plate dimensions and materials that's highly instructive - subscribe and get access to their online database of test reports).
I also don't think that having a double bolt helps in case of stress corrosion. Once one of the bolts breaks, the fitting is liable to pull open under moderate loads.
However, I fully sympathize with anyone who just prefers that design. Whether it is because it cannot rotate, or for any other reason.
~ green ~ lake ~ ~