I can tell you from years of working on clean room equipment and toxic
gas systems that 316 stainless is the only way to go. I've always
bought the highest grade stainless fasteners I can find for above and
below the waterline, in salt water, and they hold up great. I seldom
use bronze, so I can't compare it to that.

Watch out when you buy a "stainless" item from the mail order or chain
marine supplier. If the description doesn't specifically say 316 grade
stainless, it's a good bet that it's been "watered down" with cheaper
metal. I once bought a chart light that plugged into a cigarette
lighter. It was "stainless", but you could have fooled me because it
was totally rusted and pitted in just a few months from the ocean air.
I had to get pretty assertive to get my money back on that pricey piece
of junk. If the price seems unusually low, it's a good bet the grade
is inferior. But you'll find high priced junk too.

One thing I've noticed about good stainless is that it will have a very
slight (if at all) attraction to a magnet. The cheap stuff, depending
what the metal content is could be drawn to a magnet in a much stronger
way.

There really is a huge difference.


pete wrote:
Hi, I need a forestay attatchment for my boat, someone has proposed
304 stainless steel instead of 316. As its a pretty important part of
my rig, I'm a bit dubious, but I don't know if its any more likely to
be corroded. A lot of it will be buried in the stem, but a lot of it
will also pop out above deck to take the forestay.

Any advice? I feel uneasy about 304.

Cheers, Pete