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direction Suppose the wind to be blowing from the top to the bottom of this page, a vessel can yet sail from the bottom to the top. To do so, however, she would have to tack, and her progress would be a zigzag one, as shown in Fig. 9. Upon looking at Fig. 10 you will see that the sail (A) is trimmed at such an angle with
the keel that it will just be full D
of wind. The wind catches it and glances off in the direction of the dotted lines. Now, if you were to put a billiard ball at the same angle it would fly off, not
in the direction of the stroke, C
but in another at an angle with it. So in the case of the wind. The force is—to use the technical term_resolved into other forces operating in the direction of the strokes on the opposite side of the sail. Now the sail cannot be blown sideways towards B, because of the great lateral resistance of the keel, so that the force that way is lost-save to blow the vessel over (a result which her stability strives to prevent);
but the forward forces in the A' FIG. 9. TACKING.
direction of C have a minimum of resistance offered to them, so the sail and the vessel it drags progress in that direction. The reader may get a better idea of this action of the wind if he opens and shuts the door of his room a few times and notes how the latch is forced in a certain direction by a force at right angles to that direction.
To go back to Fig. 9. A yacht will sail against the wind at about the angles shown. By a reference to the compass, herein
, after delineated, it will be seen that the vessel goes about 4 or 41 points from the wind.
In the figures from A to B she is on the port tack—that is, the wind is on the left or port side; from B to O she is on the starboard tack, the wind being on the starboard side ; and from O to D she is on the port tack again.
At the points B and C she has put the helm down—that is, to leeward—so that the rudder goes to windward and turns her head round, and the wind comes on the other side. This operation, called tacking, will be afterwards explained.
The flatter the sails are the more perfect will be the effect of the wind If
В they could be as
FIG. 10. DIAGRAM ILLUSTRATING EFFECT OF WIND. flat as a board the yacht would sail much faster, but that perfection of flatness cannot be achieved. In the best cut sails there is some curve or bag, and the more there is the worse the vessel sails to windward.
From what has been said upon stability, it will be seen that upon it depends the power to carry sail, and upon the power of a vessel to carry sail depends, in a great measure, her speed. We say, in a great measure, because the form of a vessel has a great deal to do with speed.
A vessel with bows as round as a tub, however much sail she could carry, would not sail so fast as a sharp-bowed vessel with half her canvas. All things have to be proportioned to each other. Seeing that a vessel under way is constantly displacing her exact weight of water, if she is of deep draught she must be narrow, or her displacement will be too great. If she is of shallow draught, she must be broad, or she will not be able to carry enough sail. The lines of a boat, that is, the curves which correctly delineate her form will be gathered from these articles as they progress.
Before going further it will be well that the reader should master the technical names of the different parts of a yacht, as they will be in constant use, and the next chapter will give that information.
THE RIGGING AND SPARS OF A CUTTER.
We select a cutter yacht for reference because it comprises everything which will be referred to in the chapters on sailing boats, although the practice of sailing a cutter will come after that of a boat.
The first diagram shows the deck plan of a boat (Fig. 11).
The narrowest part is the stem, on either side of which are the bows; this is all called the fore part of the boat. Amidships is the beam, followed as we go aft by the quarters, and finally the stern. A is the bowsprit bitts, into which the heel of the bowsprit is stepped ; B is the mast, C the rudder head, D the tiller, E bowsprit, F bowsprit shroud, G whiskers, and abaft of the rudder head is the counter, which is the portion of the vessel sloping upwards from the keel, abaft of the stern post, as
shown in the next diagram (Fig. 12): i stem, ii keel, iii stern-
The chief spar is the mast, and on the top of this is the