Hello Ken, I once needed to change my boomkin stays in a location that did not have a rigger. I used plated chain, not galvanized. Regrettably, I do not recall whether I used 5/16 or 3/8". At any rate, I sailed on down the coast to San Francisco , across to Hawaii, and then back to Portland, Oregon. I pushed the boat a bit hard and flew the Spinnaker most of the way across. This put max load on those stays. I had no problems and see no problem. I changed those stays back to 5/16" SS wire after I found some money. Good luck, Dave Edit: I found the chain I used for that trip and it is 3/8"
