when to vang?

I have read a decent amount on vanging and been sailing for a few seasons now, but it is still unclear to me when and how to vang. I read in the Highlites that Sandy Douglas recommended vanging to bring the upper batten parallel to boom and in higher air--15 knots and up--to vang so the batten points away from the boom to spill some air. But then I read Gough about vanging staring at 10 knots and vanging so tight as to bend the boom 3-4 inches, getting the main very flat. But doesn't vanging that hard bring the upper batten in toward windward rather than parallel? Or, in high air, doesn't such tight vanging not allow the air to spill at the top of the main as Douglas advised. Any advice or clarification of what I am reading would be appreciated.

What sails and rig tension are you running?

John McLaughlin
Ngulule
Customflex #1554

loose rig with Schurr sails

s

Sandy's article is out of date.

The vang does several things. One, it pulls down on the leech of the main and therefore pulls back on the top section of the mast, which has the effect of tightening the forestay. Tighter forestay is better for pointing and depowers the jib. The heavier the breeze, the more you want to point, not foot, so you want a tighter forestay. Ergo, heavier breeze, tighter vang is faster.

A tighter vang also pushes forward the midsection and lower section of the mast, which flattens the mainsail. This depowers the mainsail, helps prevent excessive heel and allows you to point and not slide sideways. This is probably the most important effect of heavy vang tension.

Finally, a tighter vang does hook the main leech more to windward, especially in the upper section of the leech. While theoretically, a hooked to windward leech would cause additional windward helm (something to be avoided), in actual practice in heavy air you will find the leech won't ever hook to windward because the wind blows the leech back. And sometimes you can use that additional windward helm, in combination with easing the main and hiking hard to keep the boat flat, to pinch or point even higher.

Frank, no amount of discussion can substitute for time on the water. My advice is get out there and put your boat in racing mode and sail upwind in a variety of wind velocities and play with your vang tension and see what it does to your speed, heeling and pointing.

Jay
FS 5698

Jay:

Thanks. Your explanation made everything click!! Just to make sure I understand one part: in practice, vanging real tight for high air does not bring the upper batten to windward. The wind actualloy keeps it parallel to or out a few degrees from boom. Is that right?

Frank