ABOARD (_à bord_, Fr. _abordo_, Ital.) the inside of a ship: hence any person who enters a ship is said to go _aboard_: but when an enemy enters in the time of battle, he is said to _board_. A phrase which always implies hostility. See the article BOARDING. To fall ABOARD of, _aborder_, to strike or encounter another ship, when, one or both are in motion; to be driven upon a ship by the force of the wind or current. ABOARD-_main-tack!_ _amure la grande voile!_ the order to draw the main-tack, i. e. the lower corner of the main-sail, down to the chess-tree. See CHESS-TREE. ABOUT, _reviré_, (_abutan_, Sax.) the situation of a ship immediately after she has _tacked_ or changed her course by going about, and standing on the other tack. See TACKING. ABOUT-SHIP! _adieu-va!_ the order to the ship’s crew to prepare for tacking. ABREAST, _par le travers_ (of _breost_, Sax.), side by side, or opposite to; a situation in which two or more ships lie, with their sides parallel to each other, and their heads equally advanced. This term more particularly regards the line of battle at sea, where, on the different occasions of attack, retreat, or pursuit, the several squadrons, or divisions of a fleet, are obliged to vary their dispositions, and yet maintain a proper regularity by sailing in _right_ or _curved_ lines. When the line is formed _abreast_, the whole squadron advances uniformly, the ships being equally distant from, and parallel to each other, so that the length of each ship forms a right angle with the extent of the squadron or line _abreast_. The commander in chief is always stationed in the center, and the second and third in command in the centers of their respective squadrons. See this farther illustrated in the article LINE. ABREAST, within the ship, implies on a line with the beam, or by the side of any object aboard; as, the frigate sprung a leak abreast of the main hatch-way, i. e. on the same line with the main hatch-way, crossing the ship’s length at right angles, in opposition to _afore_ or _abaft_ the hatch-way. See ABAFT. _We discovered a fleet ABREAST of Beachy-Head_, i. e. off, or directly opposite thereto. ACORN, _pomme de girouette_, a little ornamental piece of wood, fashioned like a cone, and fixed on the uppermost point of the spindle, above the vane, on the mast-head. It is used to keep the vane from being blown off from the spindle in a whirlwind, or when the ship leans much to one side under sail. See plate I. fig. 1. where _a_ represents the acorn, _b_ the vane and stock, _c_ the spindle, and _d_ the mast-head. ADMIRAL, _amiral_, an officer of the first rank and command in the fleet, and who is distinguished by a flag displayed at his main-top-mast-head. Also an officer who superintends the naval forces of a nation, and who is authorised to determine in all maritime causes.