I'm just a learner with my 17, so surprises still abound. I found that an accidental gybe (always a risk in the fluky winds where I am sailing) can hang the boom in the backstay if the main is single- reefed. I generally pull the boom across by hand to cushion the shock of a gybe, so the boom does not ride up, but big gusts can be unpredictable if they are not touching the lake surface. Anyway, a vang seemed unnecessary with the mainsheet in mid-cockpit, but now think a small four-part might hold the boom down enough to keep it clear of the backstay under unusual conditions. Any thoughts? On another sail subject, I arbitrarily set the boom at a height that put the head of the main maybe 6 inches from the masthead. I tried raising the main to the top of the slot, but the roach in my (presumably stock) Elliot-Pattison main puts a good chunk of the sail--and the upper batten--a few inches outside the backstay. Has anyone had a broken batten or a hung sail during tacking with this configuration? I prefer not to learn the hard way. Thanks, Tom Jenkins 2004 M17 Scintilla