The centre of rotation is not necessarily at the centre of the ship. On the contrary, as vessels are now built, it may not be much abaft that part of the deck to which the main tack is boarded. For the main breadth, or dead-flat, being there, the greatest cavity will also be there, and of course the principal weight of the cargo should centre there, as being the strongest part. Therefore the centre of rotation will greatly depend upon proper stowage. If the ship is much by the stern, the centre of rotation will be carried aft, and if by the head, it will be carried forward. The cause of this is, that when loaded down by the stern, her after sails have but little effect to move her stern against the water, and a very slight action upon the forward sails will send her head off to leeward, as she is there light and high in the air. Accordingly, to keep her in a straight line, the press of sail is required to be further aft, or, in other words, the centre of rotation is further aft. If a ship is loaded down by the head, the opposite results follow, and more head and less after sail is necessary.
A ship should be so stowed, and have her sails so trimmed, that she may be balanced as much as possible, and not be obliged to carry her helm much off the line of her keel, which tends to deaden her way. If a ship is stowed in her best sailing trim, and it is found, when on a wind, that her head tends to windward, obliging her to carry a strong weather helm, it may be remedied by taking in some after sail, or adding head sail. So, if she carries a lee helm, that is, if her head tends to fly off from the wind, it is remedied by taking in head or adding after sail. Sometimes a ship is made to carry a weather helm by having too much head sail set aloft. For, if she lies much over on a wind, the square sails forward have a tendency to press her downwards and raise her proportionally abaft, so that she meets great resistance from the water to leeward under her bows, while her stern, being light, is easily carried off; which, of course, requires her to carry a weather helm.
The general rules, then, for turning a ship, are these: to bring her head to the wind,—put the helm to leeward, and bring the wind to act as much as possible on the after sails, and as little as possible on the head sails. This may be done without taking in any sail, by letting go the head sheets, so that those sails may lose their wind, and by pointing the head yards to the wind, so as to keep the head sails shaking. At the same time keep the after sails full, and flatten in the spanker sheet; or, if this is not sufficient, the after sails may be braced aback, which will send the stern off and the head to windward. But as this makes back sails of them, and tends to send the vessel astern, there should be either head or centre sails enough filled to counteract this and keep headway upon her. On the other hand, to turn the head off from the wind, put the helm to windward, shiver the after sails, and flatten in the head sheets. Brace the head yards aback if necessary, being careful not to let her lose headway if it can be avoided.
The vessel may be assisted very much in going off or coming to, by setting or taking in the jib and spanker; which, if the latter is fitted with brails, are easily handled.
CHAPTER XI.
TACKING, WEARING, BOXING, &C.
Tacking without fore-reaching. Tacking against a heavy sea. Hauling off all. To trim the yards. Flattening in. Missing stays. Wearing—under courses—under a mainsail—under bare poles. Box-hauling—short round. Club-hauling. Drifting in a tide-way. Backing and filling in do. Clubbing in do.
Tacking.—Have the ship so suited with sails that she may steer herself as nearly as possible, and come to with a small helm. Keep her a good full, so that she may have plenty of headway. Ready, About! Send all hands to their stations. The chief mate and one, two, or more of the best men, according to the size of the vessel, on the forecastle, to work the head sheets and bowlines and the fore tack; two or more good men (one usually a petty officer, or an older and trusty seaman) to work the main tack and bowline. The second mate sees the lee fore and main braces clear and ready for letting go, and stands by to let go the lee main braces, which may all be belayed to one pin. Put one hand to let go the weather cross-jack braces, and others to haul in to leeward; the cook works the fore sheet, and the steward the main; station one or more at the spanker sheet and guys; and the rest at the weather main braces.
Ease the helm down gradually; Helm's a-lee! and let go the jib sheet and fore sheets. As soon as the wind is parallel with the yards, blowing directly upon the leeches of the square sails, so that all is shaking, Raise tacks and sheets! and let go the fore and main tacks and main sheet, keeping the fore and main bowline fast. As soon as her head is within a point or a point and a half of the wind, Mainsail haul! let go the lee main and weather cross-jack braces, and swing the after yards round. While she is head to the wind, and the after sails are becalmed by the head sails, get the main tack down and sheet aft, and right your helm, using it afterwards as her coming to or falling off requires. As soon as she passes the direction of the wind, shift your jib sheets over the stays, and when the after sails take full, or when she brings the wind four points on the other bow, and you are sure of paying off sufficiently, Let go and haul! brace round the head yards briskly, down fore tack and aft the sheet, brace sharp up and haul your bowlines out, and trim down your head sheets.