Fred...more on backstay adjustment
I checked the link to North U. The information on fractional rigs is useful, but could be confusing to a novice sailor because it shows a RUNNING backstay attached at the same height as the forestay. Unless I missed it, the fractional rig page doesn't appear to discuss the MASTHEAD backstay. Runners at the forestay attachment point can tension the forestay but can't bend the mast.The masthead backstay is a much simpler setup (runners have to switched from one side to the other when tacking the boat) but is extremely effective for bending the mast, flattening the main and opening the leech of the sail.For some reason, most books on sail trim don't explain this concept very well. Many otherwise experienced sailors can't do it either, probably because this type of rig isn't that common on cruising keelboats. On the other hand, most racers (particularly performance dinghy sailors) get it.Thanks to my "bendy" mast and adjustable masthead backstay, I've been able to sail close-hauled in heavy air, single-handed, at 15 degrees of heel with a full, flattened main, open leech and light helm when other boats were already reefed, The mind-blower for me was learning the value of pulling the traveler to windward in heavy air. It defies conventional wisdom but it works.PeterH23 "Raven"