board

A board is the distance a vessel travels in a single direction between two successive tacks when sailing to windward, that is, when trying to make progress into the wind. Since a sailing ship cannot point directly into the wind, it must sail at an angle to the wind and periodically change direction by coming about; each straight-line segment of this zigzag path is one board. The length of a board depends on the vessel's speed, the crew's skill, and the tactical situation.

The term originated from the visual appearance of a sailing vessel's course when plotted from above: the ship traces a series of parallel lines across the water, each one a board. On a chart, these appear as a series of overlapping straight edges or boards laid out in succession. The word reflects the older nautical vocabulary where geometric shapes and construction terms were borrowed to describe navigation patterns.

Long boards and short boards

In practice, sailors speak of long boards and short boards. A long board occurs when the vessel sails for an extended time on one tack before coming about, typically used when approaching the destination on a favorable heading or when the vessel has plenty of room to maneuver. A short board is a brief tack, often employed when tacking in confined waters, or when the vessel needs to cover ground in a specific direction despite the wind. Racing yachtsmen carefully judge board length to optimize their course to the mark while managing tide and current.

The efficiency of a windward course depends partly on board length. Very short boards waste time and distance in the turns themselves; very long boards may take the vessel far from the direct line to its destination. Professional sailors develop an intuition for the optimal board length based on wind strength, vessel characteristics, and the geometry of the course ahead. Modern instruments like GPS and wind instruments help formalize these decisions, but judgment still matters.