by craig on Tue Aug 16, 2016 4:21 pm
You want turnbuckles that can handle at least the safe working load of the weakest point in the system the designer has specified. That could be either the 5/32 wire or the Padeyes -- I'm not sure which is weaker. I would just go with the safe working load of the wire (700 pounds I believe) and get turnbuckles that can handle that load.
For what it's worth, I read somewhere that 20 knots of wind will exert 1 pound of force per square foot of sail. Of course then you have to consider gusts, shock loads, damaged cable, etc, and put in the appropriate safety margin. I also believe the safe working load of the blocks used for the jib and mainsail have a safe working load of 350 or so pounds, but your question was about the shrouds, so that wouldn't matter I guess.
Titania, launched January 2015