[GeorgeB]

Does your hang glider's cable have any kinks in it or is the other parts of the glider "bent"? Without seeing your boat, you probably can get away with it. If you are anywhere near a West Marine with a rig shop, I'd borrow thier swager rather than using the hardware store wire clamps (swages cost about the same). You will want to bend the cable around a pair of thimbals before you swage. How do you get tension on the headstay? turnbuckle?

To answer your question, the headstay carries the most load of all your stays. Broken strands or kinks in the wire is bad.

 

[GeorgeB]

The thimbals go on each end of the cable. Open loops of cable distort under a load. You can buy a hand swager but borrowing is cheaper. Where are you located? Cadmium or zinc plated hardware store items rust out in a season in a salt environment and a headstay failure means a rig failure and a new mast would cost more than your boat. The hardware store clamps will also leave you with meathooks which also arn't a good thing around fabric sails.