Part 2
The Sperry Gyro-Compass does not oscillate with the rolling of the ship, or in other words, has no heeling error. The use of the helm is greatly diminished. Records show that on one trans-Atlantic liner a saving of 24 percent in the revolutions of the steering engine, when steered by Gyro-Compass, was effected. One of the largest trans-Atlantic liners reports that but one-third of the helm is used when the ship is steered by Gyro-Compass.
This saving in the use of the steering engine gives actual proof that the ship navigated by a Gyro-Compass steers a straight line course. It further proves that the ship does not divert its slip-stream as often—the power output of the main engines is thereby reduced.
Records taken on a well-known passenger liner show that in making her regular trip between New York and Jacksonville, Florida, she saved more than two hours due to steering by a Sperry Gyro-Compass. A saving of 3,410 turns of her propeller was also effected. These savings were made even with much greater than the usual draft.
Records taken by means of the Sperry Recording Compass show that when the helmsman is given a certain course he can keep the ship one and one-half degrees nearer the course when steering by the Gyro-Compass than when steering by magnetic compass.
The Gyro-Compass can make great savings in money both in construction and operation of the ship. These factors are perhaps trivial when compared with the safety factor introduced by the use of the Sperry Gyro-Compass.
Due to the elimination of the many uncertainties of the magnetic compass, insurance companies are favorably disposed toward the use of the Sperry Gyro-Compass, which ultimately will result in a reduction of insurance rates.
The use of the Sperry Gyro-Compass eliminates inaccuracies due to navigation, thereby saving time, insuring the ship, the cargo, and the lives of passengers and crew.
Sperry Gyro-Compasses are operating on many of the world’s largest and fastest passenger liners and cargo ships. These ships are making savings every day of fuel used and time required to make their courses. The navigators using these compasses find that they can come very much nearer their calculated positions when steering by the Gyro-Compass. The Gyro-Compass makes the art of navigation more exact.
The Sperry Gyro-Compass is the only one to pass the service tests in the world’s navies.
_The Sperry Gyro-Compass Equipment_
The equipment which applies the principle set forth in a practical way consists of:
1. The Master, True North Compass.
2. Compass Control-Panel—for controlling the electric current.
3. Repeaters—operated from the Master Compass, and indicating its exact reading at any instant.
4. Motor-generator—for converting the ship’s current into current of proper characteristics for spinning the gyro wheels and operating the repeaters.
5. Storage Battery—for emergency operation of the equipment in case of failure of the ship’s supply.
The function of each piece of equipment and its relation to other parts is shown on pages 22 and 23.
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.
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.
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.
The Repeaters
A familiar application of the repeater principle is that used in hotels and public buildings, where a number of repeater clocks are operated from one master instrument. Likewise, the repeater used upon the bridge, the bearing repeater, and the one at the after steering station, are all operated by electricity in perfect unison with the Master Gyro-Compass and show the exact reading of the Master at any instant. Repeaters are operated by a small electric motor within each case, controlled by the transmitter at the Master Gyro. In designing the repeaters particular attention has been given to the electrical circuits so as to make all connections water, spray and condensation proof. Stuffing tubes of improved design are used at all outlets and entrances.
A miniature electric lamp within the repeater supplies the necessary illumination of the dial. The illumination can be brightened or dimmed by turning the switch handle on the face of the terminal box.
The repeaters are supplied in three styles:
1. Repeater mounted on steering stand—for use on bridge.
2. Bearing repeater mounted within pelorus stand.
3. Repeater mounted on bulkhead in Master’s room, or at the after steering station.
Special stands or fixtures can be supplied if necessary.
A metal “non-reflection” cover is supplied which can be fitted to either the bridge or the after steering repeaters. The cover has adjustable doors and a hood. Its object is to exclude all light from the top glass of the repeater except at the lubber’s line. No light will be reflected into the eyes of the helmsman. The doors can be closed until a very small sector of the repeater dial appears at the lubber’s line. Experience has proved that it is easier to watch and concentrate when only a small portion of the dial is visible. A magnifying glass can be used in conjunction with the cover so that the repeater indication can be read at a distance.
The bridge and after steering repeaters are mounted on adjustable brackets. The position of the repeater can be changed so as to allow a full face view of the dial from almost any angle.
The bearing repeater is of great aid to the navigator. The repeater is mounted within the stand and, of course, shows the exact reading of the Master Compass. In taking a bearing on a distant object or a sun azimuth it is not necessary to first set the “dumb” compass to correspond with the main compass. A constant true indication is afforded.
Installation of the bearing repeater can be made in such a position on the upper bridge so that it may be used for steering from that position as well as for taking bearings. A special pelorus stand cover can be supplied with windows to allow steering with the cover on, so as to protect the repeater from spray and the weather.
An improved design of azimuth circle is furnished which fits directly over the top of the repeater. Figures 24 and 26, on page 30, show the azimuth circle and bearing repeater in use, taking a bearing on a distant object, and on the sun respectively. This azimuth circle is so constructed as to bring the object, the spirit level and dial within the field of vision concurrently. The bearing can be taken with great accuracy. There is no possibility of the Master Compass changing its position while the pelorus is in use. Such an occurrence is not uncommon when using the ordinary pelorus or “dummy” compass.
An additional graduated ring, Figure 25, is supplied for placing under the azimuth circle so that in case the Gyro-Compass is not operating such, for instance, as when the ship is at anchor, the pelorus can still be used as a “dumb” compass. The main compass setting is made upon the ring, and the azimuth circle used in the usual manner.
The bearing repeater can be furnished with any one of three kinds of azimuth circles. The Ritchie circle is usually supplied. The purchaser also has the option of choosing either the Sperry circle or the Kelvin Azimuth Mirror.
Compass Control-Panel
The compass control-panel provides a means for controlling the various electrical parts of the Gyro-Compass, the storage battery, motor-generator and ship’s supply current. It is very compact, neat, and of good appearance. It receives electrical power from the ship’s mains and distributes it to the motor-generator set, Master Compass and repeater.
The switch panel is made up of black ebony asbestos, mounted upon angle iron. The panel is usually mounted with its back near the bulkheads, but so hinged as to admit of access to its rear.
Motor-Generator
The Motor-Generator supplied is an efficient and exceptionally reliable piece of equipment. Its purpose is to convert the ship’s supply current into electricity of the characteristics used in spinning the gyro-wheels and operating the repeaters.
Storage Battery
The complete failure of the electrical plant aboard a modern ship is an event of rare occurrence. If, however, such a contingency should occur, provision has been made for it in the Gyro-Compass equipment by supplying a storage battery of sufficient capacity to operate the entire equipment for a period of two hours. The battery is so connected electrically as to keep itself in a charged condition while the compass is operating under normal conditions.
Sperry Recording Compass
An outstanding feature of the Gyro-Compass is that it makes possible the recording of the actual courses steered by a vessel. The recording compass is connected to the electrical circuits like a repeater and follows the movements of the Master Compass. It not only indicates the heading at any instant, but also makes a graphic record on a chart. Radial lines on the chart represent the various courses. Concentric circles represent time—each small division five minutes—each large division one hour.
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.
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.
Operation
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.
Care
All of the greatest commercial aids require some care, such, for instance, as the telephone, typewriter, adding machine, duplicating machine and so on.
The magnetic compasses aboard ship receive especially watchful attention, to see that they are not meddled or tampered with. As a rule the entire ship’s crew, including the youngest apprentice, knows that the compass must in no way be handled.
It should be remembered that the Sperry Gyro-Compass is a mechanical compass. Although the very best materials, design and skill enter into its construction, it is still liable to failure. Even with that possibility, it is so superior to the magnetic compass that it more than justifies its installation use. In the same way the electric light, although liable to failure, is vastly superior to the old oil lamp. The oil lamps are seldom used, yet they are carried aboard ships for the contingency which might happen. Similarly a failure of the electric or hydraulic steering gear may necessitate the temporary use of the inefficient hand-steering gear.
_Sperry Service_
When a Gyro-Compass is sold the interest of The Sperry Gyroscope Company does not cease. Our interest in our customer is only beginning. An experienced service engineer installs every Sperry Gyro-Compass. This engineer is also available to make the first trip with the compass in order to assure its proper operation. After installation the Sperry Service Engineers are available in every large port in the world to come aboard and inspect, clean, repair and overhaul the Gyro-Compass equipment so as to keep it in first class operating condition. A radiogram sent to any of the Sperry Service Stations will bring a Service Engineer to meet your ship. During the first year there is no charge. After this period a reasonable charge is made for the service. Such a charge is similar to that at present made by compass-adjusters.
A list of the Sperry Representatives is given on the title page of this book.
Workmanship
The Sperry Gyro-Compass is an instrument of precision. From the work done by the Gyro-Compass and the objects accomplished it would be natural to class it as a scientific instrument. It is, however, more than that for the reason that it has been made strong and sturdy for operation under the most severe conditions at sea. The most expert and skilled workmanship is required to combine strength and precision, such as found in the Gyro-Compass. The Sperry organization prides itself upon having the best workmen that can be obtained for their respective vocations.
The materials used are the very best obtainable. The rigid and inflexible set of purchasing specifications insures receiving the best materials.
A well organized inspection force passes upon all material upon its receipt, and through the various manufacturing stages to the final product.
Testing
Each Sperry Gyro-Compass is on test for several days. During this time it is put through every devisable test to simulate the conditions under which it will have to operate. Figures 38 and 39 show a compass mounted on a stand which is operated by means of motor driven gears, cams, etc., so as to reproduce the roll, pitch and yaw of a ship at sea. Absolute accuracy of the Master Compass and all repeaters while operating under this condition is required.
The purchaser is thereby assured that the compass to be installed upon his ship will have had all manufacturing inaccuracies or so-called “kinks” worked out. A record of the test accompanies each compass.
Packing
Special care is taken in packing the Gyro-Compass for shipment. Experience gained from the shipment of hundreds of compasses has devised means whereby to insure the safe arrival of all parts so that installation will not be delayed.
In order that no injury may result to any parts, the Gyro-Compass is unpacked under the supervision of the Sperry Service Engineer.
The Sperry Service Organization
The Sperry Service Organization is one which serves in all parts of the world. A corps of Service Engineers, having special training at the factory in all departments relating to the Gyro-Compass, are available in nearly every large port of the world. These engineers are ready to come aboard your ship, to clean, adjust and overhaul the Gyro-Compass, thus relieving the navigator of all care other than the actual use of the Gyro-Compass.
During the war we had Service Engineers in every port where the ships of the Navy were likely to call. Our men have been in many of the naval actions and have been able to render very considerable service on many unusual occasions. For example, it was desired to place an equipment on a British ship which was on her way to the Dardanelles. The Admiralty instructed us by telegram to have an equipment and a Service Engineer meet the ship at the British Naval Station at Malta in the Mediterranean. By sending the equipment with our Service Engineer via a passenger train to the south of Italy and via destroyer to Malta we were able to meet the ship there on the day she arrived. The ship was able to stay only twenty-four hours, and as it took about four days to install the equipment, our engineer remained on board and finished the work while the ship was enroute from Malta to the Dardanelles.
This ship, the _Inflexible_, arrived at the Dardanelles just in time to join in the first naval action directed against the land batteries. During the first part of the engagement our engineer remained with the Master Compass which was installed near the dynamo room. When he saw that it was functioning properly he left it to go on deck and view the action, the effects of which he had become aware of, as a number of shells from the land batteries had hit the ship. Almost immediately after he arrived on deck a torpedo struck the ship directly under the compartment where the Gyro-Compass was located, killing every man in that compartment. Although badly damaged the ship was able to get out of range of the land batteries and reach the naval base near the Dardanelles.
The Gyro-Compass was, of course, almost totally destroyed. Shortly after the action ended our engineer was enabled to get ashore on a Greek island via one of the British destroyers. This island had a telegraph station which he used to cable us that “Equipment No. 286 is under four feet of water,” and that we should have another equipment ready to replace it. We took this telegram to the Admiralty who authorized us to have another equipment prepared to meet this ship at Gibraltar. This we did, again sending a Service Engineer who met the ship at Gibraltar, on her way back to England to be repaired and refitted.
The Sperry Service Organization stands ready to help all ships equipped with a Gyro-Compass at all times, even in emergencies such as those experienced by naval vessels.