Headboard

A headboard is the stiff plate fitted at the head of many mainsails. Instead of bringing the luff and leech to a tiny point, it spreads the halyard load over a wider area and gives the top of the sail a small flat width.

That width matters on a mainsail with roach. The headboard helps carry leech load right to the top, where a simple soft corner would distort. Larger roach and full-batten mains often need a stronger headboard and better mast hardware, because the top batten pushes into the track.

On small or very simple sails the head may just be a reinforced corner with an eye. On bigger mains the headboard is a structural fitting: light enough to hoist easily, stiff enough not to fold under halyard and leech tension.