Noun
The principal sail in a ship or other vessel.
Source: Webster's dictionaryA sloop is any boat that has a single mast and usually a single headsail (generally a jib) in addition to the mainsail ( Bermuda rig but c.f. Friendship sloop ). Source: Internet
Easing the sheets on aft-most sails, such as the mainsail in a sloop or cutter can have an immediate effect, especially to help with maneuvering. Source: Internet
On a small boat with only jib and mainsail this is done by furling the jib and by partially lowering the mainsail, a process called 'reefing the main'. Source: Internet
The mast of a fractional-rigged sloop may be placed farther forward; compared to a masthead-rigged sloop, this results in a rather smaller jib relative to the size of the mainsail. Source: Internet
On a modern fore-and-aft rigged boat the largest sail set on the main-mast is known as the mainsail, rather than main course. Source: Internet
However, as the size of the boat increases, the benefits of mainsail roller furling increase dramatically. Source: Internet