Placed at the head of mainsails, these boards provide support for additional roach area and a purchase point for the halyard. Most sails are built with external boards. That is, there are two boards that sandwich the cloth on each side of the sail. They are riveted in place (rivets can be nicely set with a center punch and hammer). Seldom is the rope run around the board. Note that this makes possible the insertion of the rope in a tunnel along the mast or boom.

Small boats can make good use of these nylon external boards—they are light and inexpensive. (Boats over 20' should use aluminum boards.) Nylon boards can be sewn in place or secured in place with rivets—these can be installed with a couple of blows of a hammer. Each headboard set includes proper rivets.

Most racing rules measure only the width of the board, not the boltrope in front of it. In the case of the IMS rule, this is limited to 4% of the E dimension or 6" — whichever is greater. MORC permits the same percentage with a 4-1/2" minimum headboard width. These limits can be exceeded, but there is a rating penalty.

To Install: Headboards should be attached at least 3/16" behind the boltrope if the boltrope will slide into the mast groove. Otherwise, the headboard can be placed right up against the back of the boltrope. Match the two boards directly opposite one another. Punch a hole in the sailcloth and insert the rivets to install the headboard pieces. When the rivets are properly installed, the two boards will compress the fabric tightly. After rivet installation, cut out the sailcloth in any openings with a utility knife and then smooth the job with a hotknife.