BACK. _To back an anchor._ To carry a small anchor ahead of the one by which the ship rides, to partake of the strain, and check the latter from coming home.--_To back a ship at anchor._ For this purpose the mizen top-sail is generally used; a hawser should be kept ready to wind her, and if the wind falls she must be hove apeak.--_To back and fill._ To get to windward in very narrow channels, by a series of smart alternate boards and backing, with weather tides.--_To back a sail._ To brace its yard so that the wind may blow directly on the front of the sail, and thus retard the ship's course. A sailing vessel is backed by means of the sails, a steamer by reversing the paddles or screw-propeller.--_To back astern._ To impel the water with the oars contrary to the usual mode, or towards the head of the boat, so that she shall recede.--_To back the larboard_ or _starboard oars_. To back with the right or left oars only, so as to round suddenly.--_To back out._ (_See Back a Sail._) The term is also familiarly used for retreating out of a difficulty.--_To back a rope or chain_, is to put on a preventer when it is thought likely to break from age or extra strain.--_To back water._ To impel a boat astern, so as to recede in a direction opposite to the former course.--_Backing the worming._ The act of passing small yarn in the holidays, or crevices left between the worming and edges of the rope, to prevent the admission of wet, or to render all parts of equal diameter, so that the service may be smooth.--_Wind backing._ The wind is said to back when it changes contrary to its usual circuit. In the northern hemisphere on the polar side of the trades, the wind usually changes from east, by the south, to west, and so on to north. In the same latitudes in the southern hemisphere the reverse usually takes place. When it backs, it is generally supposed to be a sign of a freshening breeze. BACK. The outside or convex part of compass-timber. Also a wharf. BACK, OF A SHIP. The keel and kelson are figuratively thus termed. BACK, OF THE POST. An additional timber bolted to the after-part of the stern-post, and forming its after-face. BACK-BOARD. A board across the stern sheets of a boat to support the back of passengers; and also to form the _box_ in which the coxswain sits. BACK-CUTTING. When the water-level is such that the excavation of a canal, or other channel, does not furnish earth enough for its own banks, recourse is had to _back-cutting_, or the nearest earth behind the base of the banks. BACK-FRAME. A vertical wheel for turning the three whirlers of a small rope-machine. BACK-HER. The order, in steam-navigation, directing the engineer to reverse the movement of the cranks and urge the vessel astern. BACKING. The timber behind the armour-plates of a ship. BACK-O'-BEYOND. Said of an unknown distance. BACK OFF ALL. The order when the harpooner has thrown his harpoon into the whale. Also, to back off a sudden danger.