This is a reference photo page to illustrate different maintenance issues facing saltwater boaters
Crevice Cracking Corrosion in stainless steel:
(Below) What’s happened to this stainless steel sailboat shackle is called “crevice corrosion cracking”. I’m using this as an OBVIOUS case, but the cracks can be nearly invisible and weaken the structure the same amount as these have obviously done. This phenomenon occurs in the ABSENCE of oxygen, in other words, on the back side of your chainplates, mast tangs, and other critical boat metal hardware.
(Below) Same shackle; I pulled it apart with my bare hands. You know what’s funny? I took this shackle off a mast I’d bought for one of my family’s boats; the previous owner had been using it right up til he put the boat on the rocks and didn’t need the mast anymore!