Gentlemen of advancing years and thinning hair find being hit on the head very unpleasant, so one or two of our sailors wear cycle helmets on windy days. Trapeze Harnesses and Hiking Shorts Trapeze Harnesses provide you with a hook which connects to a ring hung from the mast of the boat. The harness needs to allow you to use the trapeze correctly, move freely round the boat and not drag you under if you go in. Harnesses come in a variety of styles - the simplest has no adjustment and is made to measure. This gives no hooks or straps to catch on things, but presents a problem if you change size or wear different clothing underneath.
Modern harnesses have back supports, adjustable straps, pockets and all sorts of gizmos.
The main choice is between a crotch strap or leg straps. I find the latter uncomfortable, but most men find the former agony. I use a harness that laces up at the sides, which fits well and has minimal protrusions to tangle in the boat, but is impossible to remove in a hurry. Strap-fastening harnesses can be released more easily, but can catch on things. Your harness should be fastened so that you can't stand up straight, as this provides the best support when you are out on the wire.