Well, I measured it today, and the hogged-out hole and surrounding corrosion is about 3/4" in diameter, so I don't think that going to the next-size larger rivet will help that <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" /> Shall I just leave that corrosion, and drill/rivet an inch or two away?

Hobienick, you referred to a rivet "cover", and WindyHillF20, you referred to a "sleeve". The closest thing I could find was what Murray's Marine calls a "Rivet Casing": 6-10 (3/16 x 1/2) Part #19-5020, @ $0.70/ea. Is that what you are talking about? Looks to be for re-riveting a 3/16" rivet that has suffered minor hogging out of the hole, instead of going to a 1/4" rivet, and sounds like exactly what I need to replace all the other suspected weak padeyes (but obviously not the big one!)

About Monel metal, looking at the galvanic series, monel is much closer to stainless steel than it is to aluminum, so I don't see how monel rivets will cause any less corrosion than stainless. I've seen references to installing rivets "hot" or "wet" (what does that mean?), or with some "Goop" as an insulation barrier, but I don't know where to find that.

Thanks for the reassurance and advice, guys.
-Alex