1. Among the maneuvers most frequently encountered is that wherein the line of bearing of ships is altered.

2. It is well known that if you are the leading ship in column and are ordered to take position on the bow of a ship in the column astern, that you readily reach the designated location by turning to that side by an amount equal to the bearing assigned. Maintaining standard speed, your distance from the guide remains the same.

3. Fig. 1 shows this condition graphically.

4. If *B *changes course by the given bearing a she will reach *C* at the same instant that guide *A* advances to point *B*. Thus *B *has reached a new line of bearing at the standard distance using standard speed.

5. It may not be so generally known that a like relation obtains when the ship ahead happens to be on a line of bearing other than 0°. Such however is the case, and by the use of this knowledge a simple thumb rule will suffice and instead of the necessity for the use of the mooring board, the desired change of course is had instantly.

6. Referring to Fig. 2 the problem may be stated.

7. Ship at *A,* distant *CA* from guide *C *and bearing from the latter angle *a,* desires to reach a position bearing angle *ß *from guide at a distance equal to former distance* CA*. Assume equal speeds.

8. Let ship stand on such a course from *A *that at a given instant she arrives at a point which bears angle *ß* from guide at distance required. Call this point *P.*

9. In the figure *CB* and *AD* represent the original course. Angle *DAP *is the angle between original course and course to desired point* P*. We wish to find a value for angle *DAP*.

10. Draw *CP.*

12. So, at same speed as guide, to move to a new bearing from guide greater than that already held, at same distance, simply change course away from guide an amount equal to the *sum of the old and new bearings*. Should this angle be greater than 180° it is simpler to subtract from 180° and turn toward the guide by this amount.

13. In practice the arrival of the ship at *P* is determined by the use of the pelorus, checked by the rangefinder for distance, the ship turning up to her course just before the bearing and distance are obtained. For runs of some distance the time required is quickly found by multiplying the distance between tracks by the cosine of the change in course and dividing by speed.

14. Those interested will find the above rule to apply also to some cases where the bearing is altered from one bow of guide to the other, or from one quarter to the opposite. However, in doing any of these stunts do not forget that the guide is a ship and not a point on a line.