Here were the parting words of my rigger, which I kept for my records:
"Regarding your rig; you want to pre-stretch the wire to about 10% of its breaking strength. The tensile strength can be found online (even West Marine's catalog) for each diameter of wire, these calculate 10% and look for that number on your gauge. The inner forestay will get less (5 to 8%) and the backstays
can have more (12 to 15%). Don't be a total slave to the gauge, keep the rig happy. You can also just snug the leeward shrouds while sailing. Count the number of turns, tack the boat and take up the exact number on the opposite side. You are trying to keep the rig in column and relatively stable. And remember, it is not designed as a race
boat! Treat it as two panels
, upper and lower, separated by your spreaders. Lower shrouds control the lower panel, caps and intermediates the upper. You generally tune from the top down. DO NOT forget to re-pin the turnbuckles when done!"