A. The highest class of the excellence of merchant ships on Lloyd's books, subdivided into A 1 and A 2, after which they descend by the vowels: A 1 being the very best of the first class. Formerly a river-built (Thames) ship took the first rate for 12 years, a Bristol one for 11, and those of the northern ports 10. Some of the out-port built ships keep their rating 6 to 8 years, and inferior ones only 4. But improvements in ship-building, and the large introduction of iron, are now claiming longer life. A is an Anglo-Saxonism for _in_ or _on_; as _a_'board, _a_'going, &c. A.B. The rating of _Able Seamen_ on the ship's books: these two letters are often used as an epithet for the person so rated. He must be equal to all the duties required of a seaman in a ship--not only as regards the saying to "hand, reef, and steer," but also to strop a block, splice, knot, turn in rigging, raise a mouse on the main-stay, and be an example to the _ordinary seamen_ and _landsmen_. ABAB. A Turkish sailor who plies in coasting craft. ABACK. The situation of a ship's sails when the wind bears against their front surfaces. They are _laid aback_, when this is purposely effected to deaden her way by rounding in the weather-braces; and _taken aback_, when brought to by an unexpected change of wind, or by inattention in the helmsman.--_All aback forward_, the notice given from the forecastle, when the head-sails are pressed aback by a sudden change in the wind. (_See_ WORK ABACK.)--_Taken aback_, a colloquialism for being suddenly surprised or found out. ABACUS. A board with balls sliding on small rods, used in China, Russia, &c., for calculating bills, &c. ABAFT. This word, generally speaking, means behind, inferred relatively, beginning from the stem and continuing towards the stern, that is, the hinder part of the ship.--_Abaft the beam_ implies any direction between a supposed transverse line amidships and the stern, whether in or out of the ship. It is the relative situation of an object with the ship, when that object is placed in the arc of the horizon contained between a line at right angles with the keel and the point of the compass which is directly opposite the ship's course. An object--as a man overboard--is described by the look-out man at the mast-head as abeam, before, or abaft the beam, by so many points of the compass. As a vessel seen may be "three points before the beam," &c. ABAKA. A fine vegetable fibre, with which the white Manila rope, so much used on the India station, is made. This rope floats in water, and is not subject to rot, nor does it require tarring. A frigate on the China station in 1805 had nearly the whole of her running rigging of this cordage.