Boom vang (Kicking strap)

The boom vang (US) or kicking strap (UK) is a line or piston system used to exert downward force on the boom, controlling mainsail shape. As Wikipedia explains, it typically runs from the mast base to a point on the boom, often incorporating a purchase system for mechanical advantage. Without a vang, the mainsheet must control both horizontal and vertical boom angles; when the boom is eased out, the mainsheet becomes horizontal and loses downward effectiveness. The vang counteracts this, maintaining tension on the leech and reducing sail twist. On a reach or run, properly adjusting the vang flattens the sail and improves speed. On smaller boats, a simple tackle may suffice, while larger yachts use hydraulic vangs for ease. Understanding how to handle such rigging is essential, and our article on yacht rope handling: winches and blocks for beginners provides a practical guide. For a deeper dive into sail control, explore the sail handling and trim techniques tag. The vang works in tandem with the mainsheet and traveler to optimize sail shape across all points of sail.