Generic Tuning Guide

1/4" Breaking Strength = 8,200 lbs
5/16" Breaking Strength = 12,500 lbs

It is suggested that the initial settings are about 10-12% of breaking strength of wire

Selden masts has a very good tuning guide

http://www.seldenmast.com/_download.cfm?id=6740&download=9445082&filenam...

On Pages 34 & 35 is the mast guide for our style rig (Masthead with single spreader and forward and aft lower)