[COPYRIGHTED]

U. S. NAVAL INSTITUTE, ANNAPOLIS, MD.

IMPROVED MANEUVERING AND MOORING BOARD Designed by LIEUTENANT H. J. REUSE, U. S. Navy

The maneuvering and mooring board described below will be found useful in making approaches at target practice, changing position in formation and working out mooring problems. It is believed that most maneuvering and mooring problems can be worked out in much less time and with less labor than when using the regulation mooring board.

The board consists of a movable compass rose a, graduated from 0° to 360°, so arranged as to move about the center and along the edge of the board. The compass rose can be clamped in any convenient position at the top of the board, its position depending on the conditions of the problem.

Under the compass rose a is another rose b, graduated on either side of d from o° to 90° and from 90° to o°. b is arranged to move along the board with a, but does not turn about the center, a key preventing the movement. Pivoting about

the center of both compass roses is an arm c, graduated in yards to the same scale as the plotting sheet. Any number of scales can be used on the same arm. In this case inch equals 100 yards and 200 yards, respectively. The arm is also graduated in inches from zero to 30 inches. A pointer is attached to the arm, so that either the direct or reverse bearing can be read off the compass rose.

The protractor e consists of a compass rose having two arms, f and g, pivoting about the center. The arm ƒ can be clamped on any course or bearing desired, while g is free to move about the center of the rose. Both have pointers, so that either the direct or reverse bearing can be read. Both arms are gradu

ated in yards to the same scale as the arm c, and are also graduated in knots. In this case, one-half inch equals I knot, although any arbitrary scale may be used provided both arms are graduated the same. A pair of cross wires locates the center of the compass rose.

The plotting sheet, mounted on the board, is of cross-section paper, four squares to the inch. In this case one side of a square equals 25 yards or 50 yards, depending on the scale used. Every fourth line is drawn in red ink to facilitate plotting.

The diagram near the lower right-hand corner will be found useful in determining the time required to perform the evolution and will be explained in connection with examples of problems given below.

In the sketches of problems, the cross-section is not drawn. The black horizontal and vertical lines shown are those nearest the plotted positions on the plotting sheet. The full lines in red ink are the only lines required to be drawn in working out the problems. In some cases it is not necessary to draw any lines, as shown in Examples 3 and 5. In Example 5 the turning circle need not be plotted.

In some cases where it is desired to moor on a given bearing from another ship's anchor, the compass rose a cannot be used. In such cases, however, all the plotting can be done at any convenient position on the board, using the protractor. One arm can be clamped on north and laid parallel to the vertical lines, or on east, laying the edge parallel to the horizontal lines. By using the protractor the various bearings and distances entering into the problem can be laid off much more quickly than with dividers and parallel rulers as in the case when using the regulation mooring board.

EXAMPLE I

Forming on a moving ship, preserving the bearing. Speeds unequal.

C, standing on course 50° magnetic, speed 12 knots, signals A, who is bearing 290° magnetic, distant 1200 yards, to close in to 800 yards and maintain bearing. A's available speed is 16 knots. Find A's course, distance and time required to perform the evolution.