
In
sailing
Sailing employs the wind—acting on sails, wingsails or kites—to propel a craft on the surface of the ''water'' (sailing ship, sailboat, raft, Windsurfing, windsurfer, or Kitesurfing, kitesurfer), on ''ice'' (iceboat) or on ''land'' (Land sa ...
and
boating
Boating is the leisurely activity of travelling by boat, or the recreational use of a boat whether powerboats, sailboats, or man-powered vessels (such as rowing and paddle boats), focused on the travel itself, as well as sports activities, suc ...
, a vessel's freeboard
is the distance from the
waterline
The waterline is the line where the hull of a ship meets the surface of the water.
A waterline can also refer to any line on a ship's hull that is parallel to the water's surface when the ship is afloat in a level trimmed position. Hence, wate ...
to the upper
deck level, measured at the lowest point of
sheer where water can enter the
boat
A boat is a watercraft of a large range of types and sizes, but generally smaller than a ship, which is distinguished by its larger size or capacity, its shape, or its ability to carry boats.
Small boats are typically used on inland waterways s ...
or
ship
A ship is a large watercraft, vessel that travels the world's oceans and other Waterway, navigable waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research and fishing. Ships are generally disti ...
.
In commercial vessels, the latter criterion measured relative to the
ship's load line
The load line, also known as Plimsoll line, indicates the legal limit to which a ship may be loaded for specific water types and temperatures in order to safely maintain buoyancy, particularly with regard to the hazard of waves. The load line is ...
, 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
An ocean liner is a type of passenger ship primarily used for transportation across seas or oceans. Ocean liners may also carry cargo or mail, and may sometimes be used for other purposes (such as for pleasure cruises or as hospital ships). The ...
, also helps weather waves and so reduce the likelihood of being washed over by full water waves. A low-freeboard vessel is susceptible to taking in water in rough seas. Freighter ships and
warship
A warship or combatant ship is a naval ship that is used for naval warfare. Usually they belong to the navy branch of the armed forces of a nation, though they have also been operated by individuals, cooperatives and corporations. As well as b ...
s use high freeboard designs to increase internal volume, which also allows them to satisfy
International Maritime Organization
The International Maritime Organization (IMO; ; ) is a List of specialized agencies of the United Nations, specialized agency of the United Nations responsible for regulating maritime transport. The IMO was established following agreement at a ...
(IMO) damage stability regulations, due to increased
reserve buoyancy
The load line, also known as Plimsoll line, indicates the legal limit to which a ship may be loaded for specific water types and temperatures in order to safely maintain buoyancy, particularly with regard to the hazard of waves. The load line is ...
.
See also
*For the term as used in measuring sea ice, see
Sea ice thickness
Sea ice thickness spatial extent, and open water within sea ice packs can vary rapidly in response to weather and climate. Sea ice concentration is measured by satellites, with the Special Sensor Microwave Imager / Sounder (SSMIS), and the ''Euro ...
.
References
Notes
Bibliography
*
*
{{Authority control
Nautical terminology
Ship measurements
de:Schiffsmaße#Freibord