A lap is when the fiberglass wraps around the
rail to the other side of the board, providing more strength. When
glassing the bottom of the
board, the fiberglass '˜laps' onto the deck. When fiberglassing the deck,
the fiberglass laps around the rail onto the bottom. The distance of the lap (measured from
rail to stringer) has a effect of the board's overall
breaking strength and flex.
A longer lap will make a more snap-resistant, stiffer board because. A
shorter lap will be a weaker and flexier board. A standard lap distance is about 1" in
towards the stringer from the apex of the rail.