by K.C. Walker » Sat Aug 01, 2015 10:14 pm
+1 for what willyhays said. Mike Gillum really helped me set up my boom vang so that it is enjoyable to use.
It does have different effects with different mast sections. My previous mast, that I broke, was much bendier than my present mast section and the vang worked somewhat differently. With a 20:1 set up and the angle of the vang shallower than 45° you get more "mast ram" effect, therefore controlling the mast bend as well as the leech of the sail. With my bendy mast if I pulled on full vang I would actually open the leech and flatten the sail by bending the mast. With less vang pulled on it would closed leech but flatten the sail. With minimal vang pulled on it controls the boom from rising but does not affect the sail depth much, though keeps it from twisting out as much. With no vang on, the boom is allowed to rise and the sail twists out and remain at full depth. With my stiffer mast it's hard to get it to open the leech by pulling on full vang, I probably need more rig tension for that.
When you use a powerful vang to control for boom height, and therefore the leech tension, your sheeting becomes more of a traveler, especially if you are using end boom sheeting with a high triangle bridle or a split tail sheet, as Mike uses. Also, you end up not having as much sheet load in hand because part of the load of pulling the boom down, actually a great deal of it, is done with the vang.
I don't know if it's luck but I have not broken anything yet and have had the set up for a number of years.
KC Walker, DS 1 #7002