The Master Compass

The Master Gyro-Compass is contained within a binnacle stand, with glass dome top.

As shown in the pho­to­graphs and sec­tion­al view, the twin gyro-wheels are sup­port­ed from a frame-work which is in turn set in gim­bal rings. The out­er gim­bal ring is at­tached to the bin­nacle stand by means of a num­ber of sup­port­ing springs. The springs are pro­vid­ed for pro­tect­ing the com­pass against sud­den jars and vi­bra­tions. Fig­ure 18 shows a pho­to­graph of the top view, while the wheels are shown from be­low in Figure 16.

A diagrammatic representation of the Sperry Gyro-Compass is shown in plan view in Figure 17. The elevation, or side view, is shown in Figure 15. These drawings show the working parts of the Gyro-Compass. Each of the twin gyro-wheels is enclosed in a case, which is in turn suspended from the main frame and spider.

The wheels are spun at a high speed in unison by means of electricity. The force of the earth’s rotation combines with the force resulting from the rotating wheels. The resultant action of these two forces is that both wheels turn their axes directly into, or parallel with, the earth’s north and south meridian. The compass card, of course, also turns and indicates direction by comparing the stationary “lubber line,” representing the ship’s head, with the compass card.

Figure 6. Control Panel.Figure 8. Master Compass.Figure 9. Storage Battery.
Figure 7. Motor Generator.
Figure 10. Repeater on Steering Stand.Figure 11. Repeater, Bulkhead Type.Figure 12. Bearing Repeater in Pelorus Stand.

The Dhow is the trading ship of East Africa.

Figure 14.

A single gyro-wheel would cons­ti­tute a sat­is­fact­ory sta­tion­ary, or “land com­pass.” On ship­board the roll, yaw and pitch of the ship would impose ad­di­tion­al duty on a single wheel. It would have to point not only True North, but also offset the effect of the sea. One of the two wheels is ar­ranged to always point True North, while its twin wheel op­poses and neutralizes all in­fluences other than the force of the earth’s rotation. The force of both wheels is utilized in seeking the mer­i­dian.

The Master Gyro-Compass is a marvel of mech­an­ical per­fec­tion and rug­ged­ness. Every ro­tat­ing or re­volv­ing part moves upon special bearings to reduce friction. It should be noted also that the gyro-wheels do not directly operate the compass card. The compass card is turned by a small electric motor (Azimuth Motor), Figure 17. The slightest change in position between the wheels and card operates the “trolley” or electrical contact, which controls the Azimuth Motor. The card is made to “shadow” the wheels. The follow-up is so close that the card frame has been called the “phantom.”

An electrical transmitter, Figure 17, is operated by the movement of the card. This transmitter is the means by which the repeaters are kept in unison with the movements of the Master Gyro-Compass, and made to show the exact reading at any instant. Again the Azimuth Motor furnishes the very slight amount of power required to operate this device.

Figure 13.

The Master Compass is placed near the center of the ship at the water line. At this point the effect of rolling is at a minimum. It is, however, not necessary to place it exactly at this position. Figure 13 shows the approximate location of the various pieces of equipment aboard ship.

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