Table is drawn up. The deviation for the first four points only out of the thirty-two is given:—
<poem> +-+++ | | | | | Ship's Head | | Correct | | by Compass. | Deviation. | Magnetic Course. | +-+++ | N. | ½ E. | N. ½ E. | | | | | | N. by E. | 1 E. | N.N.E. | | | | | | N.N.E. | 2¼ W. | N. ¼ W. | | | | | | N.E. by N. | 1½ W. | N. by E. ½ E. | | | | | | Etc. | Etc. | Etc. | + +++
The table is thus employed. Look to column 3 for the direction in which you wish to sail; the corresponding course in Table 1 is the course which you must steer by your compass. For example, by the table above, if your destination bears N. ½ E. you will have to steer N. by your compass. The points of the compass are generally expressed in degrees on a Deviation Table. (As there are thirty-two points in the circle of 360 degrees, a point measures 11¼ degrees.) Thus N.E. would be N. 45° E. But when navigating a small yacht it is unnecessary to employ these numerical subdivisions of the points of the compass; the quarter-point is a sufficiently minute division for all practical purposes. On small wooden yachts, if the compass is in the right place and proper precautions are taken, there is rarely any serious deviation.
