right Rights are law, legal, social, or ethics, ethical principles of freedom or Entitlement (fair division), entitlement; that is, rights are the fundamental normative rules about what is allowed of people or owed to people according to some legal sy ...

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 (watercraft), 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, wi ...

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 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 the force exerted by a fluid opposing the weight of a partially or fully immersed object (which may be also be a parcel of fluid). In a column of fluid, pressure increases with depth as a result of the weight of t ...

; 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 and

Vikings Vikings were 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 settled throughout parts of Europe.Roesdahl, pp. 9� ...

. 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 of a watercraft, important for stability. On some sailboats, it may have a fluid dynamics, hydrodynamic and counterbalancing purpose as well. The keel laying, laying of the keel is often ...

s - Most sailing ships and larger sailboats have deep

keel The keel is the bottom-most longitudinal structural element of a watercraft, important for stability. On some sailboats, it may have a fluid dynamics, hydrodynamic and counterbalancing purpose as well. The keel laying, laying of the keel is often ...

s containing ballast 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