Warning of Unreliability

Due to mag­net­ic storms and any num­ber of other causes the mag­net­ic com­pass may at any time be dis­trac­ted so that it does not in­di­cate cor­rect­ly. Dis­tur­bances are ex­tran­eous and their di­rec­tion and mag­ni­tude can­not be de­ter­mined. The nav­i­gat­or is cons­tant­ly sub­ject to the feel­ing that his comp­ass may not be ac­cu­rate—that he can­not de­pend on it.

About the only thing that will cause an er­ror in the Gy­ro-Com­pass is the fail­ure of the el­ect­ri­cal power sup­ply. Should this con­tin­gen­cy oc­cur an elec­tric bell warns the nav­i­ga­tor. Any dis­tur­bances must orig­i­nate with the mas­ter com­pass and can be quick­ly and ac­cu­rate­ly lo­cated.

The Sperry Gyro-Compass unfailingly points True North under all conditions of weather, ship or cargo. It relieves the navigator of calculation of errors, and tiresome compass compensations. It makes a great saving in time required to “swing ship.” The Sperry Gyro-Compass is, therefore, the Ideal Compass.

The Great Eastern laid the first Atlantic cable.

Advantages Attending the Use of the Sperry Gyro-Compass

URING the construction of a steel ship it is usual to build it on ways the direction of which lie in the East-West line. Should the ways be placed in a North-South line the riveting on the keel and plates tends to help the molecules of metal to place themselves parallel to the magnetic lines of force, and magnetize the metal. When placed in the East-West line the molecules of metal in the plates are at right angles to the magnetic lines of force, and are not as easily magnetized. The use of the Gyro-Compass eliminates the necessity of placing the ways in the East-West line.

After a large ship has been launched, and during the fitting out period, it is often necessary to have it swung end for end in order to neutralize or equalize the magnetism induced by the earth’s magnetic field. To swing a large ship end for end costs anywhere from one thousand ($1000) to three thousand ($3000) dollars. The Gyro-Compass is unaffected by any magnetic phenomena, and is so dependable that it makes the swinging of the ship unnecessary.

In constructing a ship it is customary to make all metal parts within approximately ten (10) feet of the magnetic-compass stand of bronze, brass or other non-magnetic material. The proximity of magnetic metals seriously affects the accuracy of the compass. All electric leads are run so as to clear the vicinity of the compass, as the magnetic fields set up by such conductors seriously influence the compass needle. Actual experience is on record that the total installation cost of the Sperry Gyro-Compass has been saved many times over by the elimination of special metals and special run of electric leads.

Before starting on a long voyage, es­pec­ial­ly with a new ship using the mag­ne­tic compass, it is cust­o­mary to swing the ship through a comp­lete circle to check dev­i­a­tion. To swing ship it is first nec­es­sary to pick out a suit­able ob­ject on land having a known bear­ing to the ship. This object is used as a ref­er­ence point. If at sea ob­ser­va­tions are taken on the sun. The ship is then swung through 360 degrees, stop­ping usually on each 15-degree head­ing, and noting the dev­i­a­tion. A table is made up showing the deviation on each of these headings. An attempt is then made to so adjust or manipulate the compensating magnets to eliminate the error found. The ship must then again be swung through 360 degrees, stopping at headings as before to check the applied compensation.

A Stern-wheeler of early steam-boating days.

Figure 5. Errors of Magnetic Compass Cause Departure From Desired Course.

On some ships it is the custom to check the deviation by the deflector magnet method. The ship in this case is put on a certain heading and a magnet placed to one side of the compass and the deviation noted. The same magnet is then placed at an equal distance to the opposite side and the deviation noted. The difference, if any, between the readings is the deviation on that particular course.

With either meth­od of check­ing for dev­i­a­tion, con­sid­er­able time is used. It is not nec­es­sary to check for dev­i­a­tion or ap­ply any com­pen­sa­tion to the Gyro-Com­pass, as it is not mag­net­ic. In fact the Gy­ro-Com­pass has noth­ing what­ever to do with magnetism.

When at sea the Gyro-Compass af­fords the means of keep­ing to the straight-line, true course. The line A B, Figure 5, shows the straight-line course from the port of New York to the port of Liver­pool. The line A C E B shows, with exag­ger­a­tion, the actual course steered due to com­pass and other er­rors. At the point E the ship’s position was checked by observation of a celestial body. The line E B represents the new course set to bring the ship to her destination. This is an occurrence which sometimes happens not once but often during a voyage.

It is evident that a loss of time is in­volved when the ship leaves her straight line course. The in­her­ent ac­curacy of the Sper­ry Gy­ro-Com­pass en­ables the ship to keep to the straight line course, and also to steer di­rect­ly on true courses.

By keeping on a straight line course the ship is en­abled to make a good many more miles on the same num­ber of rev­o­lu­tions or turns of the pro­pel­ler. Under ex­actly the same weath­er con­di­tions a 16,000 ton lin­er made 370 miles in 24 hours at an av­er­age of 86.95 rev­o­lu­tions per min­ute per mile when steered by a mag­ne­tic com­pass, and the same lin­er made 377 miles with 85.61 rev­o­lu­tions per min­ute per mile when steered by the Gy­ro-Com­pass. This sav­ing amounts to eas­ily $50 per day for this ship. Dur­ing her elev­en-day voy­age she saved $550. At this rate of sav­ing the Gy­ro-Com­pass equip­ment is soon paid for.

The Turbinia was the first turbine steamer.

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.

Schooners are economical, needing but small crews.

The Sperry Gyro-Compass Equipment

HE equipment which applies the principle set forth in a practical way consists of:

The function of each piece of equipment and its relation to other parts is shown on pages 22 and 23.