Page:Small-boat sailing; an explanation of the management of small yachts, half-decked and open sailing-boats of various rigs; sailing on sea and on river; cruising, etc (IA smallboatsailing01knig).pdf/251

If we take a bearing of an object, sail for a known distance in a known direction, and then take another bearing of it, the distance we have made and the two bearings form a triangle of which we know the value of the angles, and of one of the sides; consequently by constructing this triangle on a sheet of paper we can easily estimate the length of the other sides and our distance from the object. The simplest method of finding one's position by taking two bearings of the same object is the one we shall adopt in the present instance. In the first place, having stood on as far as we prudently can on the port tack, we go about, and find that our vessel on the starboard tack heads up due north, sailing parallel to the coast. We now take a bearing of some object on the shore, selecting one that is over our bows and not abreast or astern of us. In this case the tower G will answer our purpose very well. We observe the angle that this bearing makes with our course, and we sail on until this angle is doubled; then the number of miles we have sailed since taking the first bearing is our present distance from G. Thus, when we tack ship at K, we find that G bears north-east of us, and therefore G K H, the angle between this bearing and the northerly course we now pursue, equals four points of the compass, or 45°. We sail on to H when G bears due east of us, so that G H Z, the angle between the bearing and our course, has doubled, being eight points, or 90°. Consequently, as any schoolboy can explain to us from his Euclid,