Sailing on the wind, or by the wind, or close-hauled, is a purely mechanical action, the motion being the result of opposing two forces, the wind pressure and the water pressure. The wind pressing on the canvas forces the boat sideways, her form causes the water to resist this movement, and as it is easier for her to progress in the direction of her length she moves that way. Her sails being arranged so as to transfer this movement in the direction of the bow, she moves ahead. It is to prevent her going sideways that a boat is given a keel or centerboard.

In sailing to windward a boat’s sails are trimmed flat—that is, the sheet is hauled in until the foot of the sail lies nearly parallel to the line of the keel. How close to being parallel depends largely upon the form of the hull, an easily driven model being able to sail with a flatter sheet than one of coarser dimensions. No rule can be laid down for trimming the sheets of a boat when sailing on the wind, it depending upon the form of the vessel, the strength of the wind, and the condition of the water.

As the movement of the boat is dependent upon the pressure exerted upon her canvas by the wind, it is necessary that the wind strike the sail on one side and fill it, and that it exert this pressure in a constant manner. Therefore, the boat’s bow cannot be kept pointing in the direction of the wind, but must be made to approach it at an angle. This angle, in a good sailing vessel, is one of 45 degrees, or four points by compass.

Let us suppose that the wind is blowing from the North. Now, if the boat’s bow is pointed North the current of air will pass along both sides of her sail and exert no pressure upon the canvas, acting just as it does upon the fly of a flag. But if we turn her head slowly round to the West we will find that the breeze begins to press on the canvas, gradually filling it until when her bow is pointed Northwest, or four points away from the wind, the whole sail will be distended with pressure. She is now said to be on a tack or board, and will move ahead in the direction Northwest.

But let us suppose that the point we wish to reach is directly North. If we continue sailing on this Northwest tack we can never reach it. In order to do so we must have the boat move in another direction. Four points, or forty-five degrees, on the other side of North is the direction Northeast. If our boat will fill her sail with a North wind when pointed Northwest she will also necessarily fill it when pointed Northeast. But how are we to get her into a position so that she will point Northeast? By performing a maneuvre which is called tacking or going about.

To do this we put the helm down, or a-lee—that is, push the tiller toward the side on which the sail is, the rudder going in the opposite direction. In consequence of this the boat’s bow begins to move toward the North. As it does so the wind leaves the sail, the canvas shakes, and then as her head swings past North the sail begins to fill again, with the breeze on the opposite side, until when she at last points Northeast it is rap full once more. That is what is called tacking a vessel.

If we continue to tack, remaining for an equal distance on each board or leg, the boat will gradually approach the North point by a zig-zag movement, until she reaches it.

Sometimes, owing to the wind not being directly ahead, we are able to remain longer on one tack than on the other. This is what is called making a long and short leg.

To properly sail a boat on the wind requires constant and minute attention to the helm and the canvas. The best way for the new hand is to sit low down in the cockpit to leeward of the tiller; this places him nearly under the boom. Let him look up and watch his sail just at the throat; here is where it will shake first. To sail the boat close he must just keep that portion of the sail shaking—or lifting as it is termed. After a few days at this work he will get so that he can tell instinctively by the feel of the boat just where she is, and will be able to keep her close without constantly watching the luff. Some skippers sail a boat by the jib luff, sitting to windward to see it; others by the feel of the wind on the face. This is a good guide at night when you cannot see the sail. But those things will come to the novice in time.

You should constantly practice altering the sheets of your boat, until you find out under which trim she goes best. You can mark the positions of the sheets by inserting between the strands of the rope a bit of colored worsted; also alter the position of the weights, either ballast or live, until you get the boat to her proper trim, as this has much to do with a boat sailing well to windward.

If when trimmed to sail on the wind a boat shows herself to be hard on the helm it may be the result of her form, of the position of her ballast, or centerboard, or through having too much after sail. If she gripes—that is, tries to go up in the wind—slack off a little mainsheet, and if she has a jib trim it flatter. If she tries to do the other thing run off to leeward; ease the jib sheets. The worst fault a boat can have is that of carrying a lee helm. Never buy a slack-headed boat; they are an abomination.

In rough-water sailing a boat going to windward wants her sheet eased. Do not trim the sails dead flat, nor try to sail the boat very close to the wind; give her what is called a good full, and keep her moving all the time. Remember, that every wave is a hill that the boat has to climb over, and she needs all the drive possible in order to do it. You must learn how to help her with the helm to take these seas easily, first by luffing and then by bearing away.

A man can only become a good windward helmsman by constant practice and by paying attention to every detail. He must have a quick eye, a firm hand and plenty of grit and strength.