Converting to and Fabricating Bronze Chainplates / Tangs

[blahman]

Hello all,

I just spent a while searching through past posts concerning this, but have some more specific questions.


I have a 32' Westsail and would like to replace my 30+ year old stainless chainplates with bronze. Initially I planned to have PTF fabricate a set, but it is fairly cost prohibitive. Instead, I believe I can do it myself, but I would like a bit of help deciding on the particular alloy and form.

My current chainplates are 24"Lx2"Wx1/4"T 304 stainless, and boomkin/bowsprit tangs 16"x1 1/4"Wx1/4"T. Talking with PTF, they mentioned wanting to increase the thickness to account for bronze's lower tensile strength and to leave room for polishing; how much thicker is necessary? 5/16", 3/8"? 3/8" is the only bar I'm finding and that seems REALLY thick!

As for the actual fabrication: would I be better off trying to find strip in the correct width, or buying a sheet and having someone chop it with a torch? Most of my strips will need a slight bend - about 15deg; what is a good way to induce this bend? I have not worked with metal this thick before, but feel I should be able to do an acceptable job.

I know to stay away from "bronze" brasses, leaving phosphor, silicon and aluminum bronzes. Which is best and/or most practical for chainplate fabrication that is not on the waterline, keeping in mind that I don't have a whole machine shop.

Lastly, my current chainplates have square holes for the carriage bolts; I've read in many places to stay away from squares due to cracks forming at the corners. What is the best method for fastening the chainplates/tangs to the hull?


Thank you for your time!
Aaron N.