right Rights are legal, social, or ethical principles of freedom or entitlement; that is, rights are the fundamental normative rules about what is allowed of people or owed to people according to some legal system, social convention, or ethical th ...

A monohull is a type of boat having only one hull, unlike

multihull A multihull is a boat or ship with more than one hull, whereas a vessel with a single hull is a monohull. The most common multihulls are catamarans (with two hulls), and trimarans (with three hulls). There are other types, with four or more ...

ed boats which can have two or more individual hulls connected to one another.

Fundamental concept

Among the earliest hulls were simple logs, but these were generally unstable and tended to roll over easily. Hollowing out the logs into a dugout canoe doesn't help much unless the hollow section penetrates below the log's center of buoyancy, then a load carried low in the cavity actually stabilizes the craft. Adding weight or

ballast Ballast is material that is used to provide stability to a vehicle or structure. Ballast, other than cargo, may be placed in a vehicle, often a ship or the gondola of a balloon or airship, to provide stability. A compartment within a boat, ship, ...

to the bottom of the hull or as low as possible within the hull adds stability. Naval architects place the center of gravity substantially below the center of

buoyancy Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the p ...

; in most cases this can only be achieved by adding weight or ballast. The use of stones and other weights as ballast can be traced back to the Romans,

Phoenicians Phoenicia () was an ancient thalassocratic civilization originating in the Levant region of the eastern Mediterranean, primarily located in modern Lebanon. The territory of the Phoenician city-states extended and shrank throughout their hist ...

and

Vikings Vikings ; non, víkingr is the modern name given to seafaring people originally from Scandinavia (present-day Denmark, Norway and Sweden), who from the late 8th to the late 11th centuries raided, pirated, traded and se ...

. Modern ships carry tons of ballast in order to maintain their stability; even heavily laden cargo ships use ballast to optimize the distribution of weight.

Uses

This is the most prevalent form of waterborne vessel.

Variations

Keel The keel is the bottom-most longitudinal structural element on a vessel. On some sailboats, it may have a hydrodynamic and counterbalancing purpose, as well. As the laying down of the keel is the initial step in the construction of a ship, in B ...

s - Most

sailing ships A sailing ship is a sea-going vessel that uses sails mounted on masts to harness the power of wind and propel the vessel. There is a variety of sail plans that propel sailing ships, employing square-rigged or fore-and-aft sails. Some ships ...

and larger

sailboats A sailboat or sailing boat is a boat propelled partly or entirely by sails and is smaller than a sailing ship. Distinctions in what constitutes a sailing boat and ship vary by region and maritime culture. Types Although sailboat terminology ...

have deep

keel The keel is the bottom-most longitudinal structural element on a vessel. On some sailboats, it may have a hydrodynamic and counterbalancing purpose, as well. As the laying down of the keel is the initial step in the construction of a ship, in B ...

s containing

which adds horizontal stabilility. * Displacement hulls - Monohull boats frequently ride deeply in the water, this is known as a displacement hull. * Planing hulls - Hulls that ride on top of the water are called planing hulls, because when they reach speed, the hulls are substantially lifted above the water; this is known as planing (to plane).

References and bibliography

* * * *

Fundamental concept

Uses

Variations

References and bibliography

See also