If the mainsail is rigged for and aft it's most often called a sloop.
After end (aft). The after end (aft) of a boat is the stern, the rear end of the boat. Ship's 'behind' if you will.
The lowest fore-and-aft sail on the main mast is called the mainsail, while that on the mizzen is called the mizzen sail. These may be any type of fore-and-aft sail, in any combination. The Scots Zulu, for example, had a dipping lug main with a standing lug mizzen.
With a square rigged sail, the wind simply pushes the boat along. With a fore and aft rigged sail, the wind is caught at an angle and slices on past the sail, pushing the sail hard down wind and a bit forward. A deep keel on the bottom of the sail boat tries to stop the downwind drift and, as a result of a bit of a push forward on the sail, the sail boat manages to scoot across the wind a bit. Square rigged ship: http://sailing-ships.oktett.net/golden-state.jpg The wind just blows the boat down wind. Fore and aft rigged sailboat (a sloop) http://2.bp.blogspot.com/_98ZiJEAKrlI/Rql8iSS1u5I/AAAAAAAAFc4/hwyku_OY29E/s400/9%2Bsm%2Bsb%2Bpassing.jpg Note that the sail boat is tipped over a bit (heeling). This is due to the wind trying to push the sail boat down wind and the bottom of the sail boat (the keel) trying to stop the drift down wind. The wind is slicing off the sails and pushes the sail boat a head a bit.
Aft is the back of a boat, the front is known as the fore
Aft is the back of the boat
Stern is the back or the boat/shop. Aft is a direction toward the back of the boat. If you are at the front and head toward the stern, you are heading aft.
Fore is the front of the boat, Aft is the back.Armed Forces Tribunal
The rear of a ship is called the stern aft To go to the rear is called going aft. The aft most part is the stern The rear of a ship or boat is called the "Aft" or the "aft end". Examples: "Take that line aft!". "When we turn, are you sure the aft end will clear that bouy?" Also nautically, "avast"The stern is the aft part of a ship or boat.
The extended keel or centerboard, the rudder, and the fore-and-aft rigging of sails all help a boat sail closer to the wind.
A lanteen sail
The question should be "What is aft on a sailboat?" since it is a direction, not a thing. Aft (or after) is anything toward the rear of the boat.