In ([Fig. 20] we have a boat with two sails. If the after sail is the more powerful, it is obvious that the wind will drive round that sail and the stern of the boat with it in the direction of the arrow C, while the head of the boat will run up into the wind. If, on the other hand, the head sail be the more powerful of the two, the bow will be driven off the wind and the boat will bear away.
The sails of a boat should be so balanced that she has a slight tendency to run up into the wind; and to counteract this weather helm, as it is called, the steersman will have to keep the rudder slightly to leeward of the line of the keel.
If a boat carrying weather helm be left to her own devices in a squall she will at once do the right thing, luff up into the wind and be in safety; whereas a boat with too much head-canvas and carrying lee-helm will run off her course and put herself in a dangerous position.
A boat should not gripe, that is, carry too much weather helm, for steering will then be very hard, and the rudder, forced far over to counteract the helm, will act as a serious drag in the water.
In balancing the sails, it must be remembered that the further out a sail is on an extremity of a boat, the greater its effect in driving that end of the boat off the wind.
Sometimes a vessel’s sails are not properly balanced because the ballast has not been stowed in the right place. It is obvious, for instance, that if ballast be shifted aft the weather helm will be diminished, for the stern of the boat will draw more water and so offer more lateral resistance, whereas the stem of the boat will draw less water, and will therefore be more easily blown round. A centre-board, again, is generally placed well forward, so it is found that when this is lowered the weather helm of the boat is considerably increased.
We have explained that a boat properly constructed and rigged can sail within forty-five degrees of the wind. Now, if it be desired to sail to some point more directly to windward than this, what is called tacking becomes necessary. This consists of sailing a certain distance close hauled with the wind on one side, and then turning round and sailing close hauled with the wind on the other side. A zigzag course is thus taken, each tack being at about right angles to the last.
One diagram of ([Fig. 21] illustrates the process of tacking with the wind right ahead, and in the other diagram the wind is a point or two off, so that one tack is longer than the other, there being, in sailor language, a short leg and a long leg.
