In plate I. fig. 7. a, represents a single block, and b, c, two double ones, of different kinds, without strops. Fig. e, f, two double tackle-blocks iron bound, the lower one, f, being fitted with a swivel, g, a double iron-bound block with a large hook, h, a snatch-block, i, a top-block, k, a voyal-block, and l, a clue-garnet-block. See SNATCH-BLOCK, TACKLE, and VOYAL. The Cat-block (plate II. fig. 15.) is employed to draw the anchor up the cat-head. See the article CAT. The swivel in the iron-bound block is to turn it, that the several parts of the rope of which the tackle is composed may not be twisted round each other, which would greatly diminish the mechanical power. The top-block is used to hoist up or lower down the top-masts, and is for this purpose hooked in an eye-bolt driven into the cap. See CAP. The clue-garnet blocks are used to draw the clues, or lower-corners of the _courses_, up to the yard, and are consequently fastened to the clues of those sails. See CLUE-GARNET. The use of the shoulder on the lower-end, is to prevent the strop from being fretted or chafed by the motion of the sail, as the ship rolls or pitches. BOARD, in navigation, (_bordée_, Fr.) the space comprehended between any two places where the ship changes her course by tacking; or the line over which she runs between tack and tack, when she is turning to windward, or sailing against the direction of the wind. See the articles BEATING and TACKING. _She makes a good_ BOARD, i. e. sails nearly upon a streight line, without deviating to leeward when she is close-hauled. See CLOSE-HAULED. BOARDING, _abordage_, an assault made by one ship upon another, by entering her in battle with a detachment of armed men; either because the efforts of the artillery and musquetry have proved ineffectual, or because she may have a greater number of men, and be better equipped for this attack than the enemy who defends herself against it. This stratagem, however, is chiefly practised by privateers upon merchant-ships, who are not so well provided with men, and rarely attempted in the royal navy; the battle being generally decided in men of war by the vigorous execution of a close cannonade. An officer should maturely consider the danger of boarding a ship of war before he attempts it; and be well assured that his adversary is weakly manned: for perhaps he wishes to be boarded, and if so, a great slaughter will necessarily follow. The swell of the sea ought also to be considered, because it may run so high as to expose both the ships to the danger of sinking.