The dial on which the chart is mounted turns with the movements of the master compass bringing the correct course under the marking point. As the time advances a line is marked on the chart showing the exact course steered at a definite time. On starting, the marking arm is at the inner edge, clockwork moves it toward the outer edge with uniform motion.
The chart shown in Figure 32 forms a valuable record. It was taken on a ship at a time a radio call was received from a burning oil tanker. Being within the distance defined by law, the ship was legally, as well as morally bound to proceed to the distressed ship. The chart shows that the course was altered to go to the tanker’s aid. It also showed the exact time, thereby establishing proof as to the fulfillment of the obligation. A few minutes later another radio call advised that the fire aboard the tanker was extinguished. The chart shows that the course was again altered to bring the vessel back on her original given course.
[Illustration: The Destroyer is the grey-hound of the sea.]
The chart further shows the actual courses steered in holding the ship on its given course. It shows just how efficiently each helmsman handles the ship. It provides an excellent method of training helmsmen to use less helm, effecting a saving by less frequent use of the steering engine.
The recording compass is a great aid to the Captain and Navigator in improving the navigating efficiency of the ship.
The recording compass can be supplied as a part of the Gyro-Compass equipment—its additional cost is small when compared to the saving and benefits derived from its use.
The operation of the Sperry Gyro-Compass is made easy by making all parts as simple as possible.
In starting the equipment it is necessary to turn but one switch. The twin wheels immediately start spinning and will in a short time come up to the normal speed.
After the speed has been attained, a short time is allowed for the wheels to cause their axes to “settle,” or, in other words, to seek and hold the meridian.
In case of failure of the ship’s supply, or other trouble, an audible signal immediately gives indication that something is wrong. This is a decided improvement over the ordinary compass, as no indication is afforded of the presence of factors which cause errors in its reading.
