
In
sailing and
boating, a vessel's freeboard
is the distance from the
waterline to the upper
deck level, measured at the lowest point of
sheer where water can enter the
boat or
ship.
In commercial vessels, the latter criterion measured relative to the
ship's load line, regardless of deck arrangements, is the mandated and regulated meaning.
In yachts, a low freeboard is often found on
racing boats, for increased speed (by reducing weight and therefore drag). A higher freeboard will give more room in the
cabin, but will increase weight and drag, compromising speed. A higher freeboard, such as used on
ocean liners, also helps weather waves and so reduce the likelihood of being washed over by full water waves on the
weather deck. A low-freeboard boat is susceptible to taking in water in rough seas. Freighter ships and
warships use high freeboard designs to increase internal volume, which also allows them to satisfy
International Maritime Organization (IMO) damage stability regulations, due to increased
reserve buoyancy.
See also
*For the term as used in measuring sea ice, see
Sea ice thickness.
*
Narco-submarine, a type of vessel that often is a surface ship with a very low freeboard.
Notes
References
*
*
{{Ship measurements
Category:Nautical terminology
Category:Ship measurements
de:Schiffsmaße#Freibord