by talbot » Wed Dec 21, 2016 6:43 pm
250lbs? Yikes! The original Johnson stay adjuster for 3/32" wire only had a breaking strength of 1000lbs. That would make the stay tension 25% of the breaking strength, even before any loading or shock. Most people have upgraded to 1/8" wire and bigger hardware, but 250 still seems like a lot. I would look at some other sources. Try North Sails.
In past discussions of rig tension on this site, some prominent racers have argued that there is no one perfect setting. Most people start with the mast tip about 6" aft of its base, measured by the main halyard hanging slack. All the wires should then be adjusted so there is no wiggle in the rig. The idea is not just tuning of the mast shape, but minimizing the shock loading during tacks and gybes. Don't try to get all the tension out with the turnbuckles; you can freeze up the screw threads. I would get the mast angle where you want it using the forestay, then fasten the main halyard to the end of the boom and tension the mast with the main sheet. With tension off the shrouds, you can tighten them by hand a few extra turns. When you releast the sheet, the wires should be tight. You can sight up the mast to see if you are still straight, and readjust as needed. (I guess you can also do it in reverse, setting the shrouds first. But you don't have as convenient and powerful a tensioning system in front of the mast. You would have to really crank on the jib halyard.)