November 16, 2017
Quantum Expert Answer
Great question. In-boom furling systems require the boom angle to remain at a fixed angle (usually 87 degrees) to allow the sail to be furled smoothly. The boom angle keeps the battens parallel to the mainsail and balance the tension on leech versus luff so that the sail winds down evenly. For cruising boats using a rigid fixed vang works pretty well. If set correctly based on the leech length of the sail they will keep the sail’s twist pretty much where it belongs. You will not be able to adapt to extremes of light air versus heavy air but you will always have a pretty good median setting.
(If you'd like to learn more about the boom vang, Daniel is referencing the article Do I really need a boom vang?)