I am replacing the chainplates (6 in number for capshrouds, forward and aft lowers) on my Rustler 36. Dimensions:10" x 1 9/16" x 3/8", material 316L. These yachts are still being built and still using 316L as chainplate material.
I have removed and tested the chainplates on my yacht (7 years old) and a sister ship (12 years old), both of whom have spent significant time in the tropics. Both suffered from surface and stress crevice corrosion (SCC) where the chainplates pass through the deck. My test for SCC is to (a) suspend the chainplate with a screwdriver through the bottom bolt-hole and tap in the middle with a hammer, then (b) to repeat the test suspending the chainplate from the hole for the rigging clevis pin. If SCC is present, then test (b) gives a dull "clank" as opposed to the clear ringing tone with test (a).
As I am about to leave for a 4 year sailing "odyssey" I want to replace the chainplates with a more corrosion resistant material, and after trying unsuccessfully to obtain Nitronic 50 at an affordable price, have decided on Nickel Aluminium Bronze (Ni 5%, Al 11%). This material seems to have at least the strength of the austenitic stainless steels and is very resistant to fatigue. It is slightly more expensive than 316L.
Although the decision is made and executed, I should be very interested to hear other views on my decision. I hope not to hear that I have taken a stupid decision, but all views (pro and contra) will be welcomed.
