Chapter 16

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.Steering Repeater in Wheel House.When at sea the Gyro-Compass af­fords the means of keep­ing to the straight-line, true course. The lineA B,Figure 5, shows the straight-line course from the port of New York to the port of Liver­pool. The lineA C E Bshows, 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 lineE Brepresents 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.

A Stern-wheeler of early steam-boating days.

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.

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

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.

Steering Repeater in Wheel House.

When at sea the Gyro-Compass af­fords the means of keep­ing to the straight-line, true course. The lineA B,Figure 5, shows the straight-line course from the port of New York to the port of Liver­pool. The lineA C E Bshows, 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 lineE Brepresents 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.

When at sea the Gyro-Compass af­fords the means of keep­ing to the straight-line, true course. The lineA B,Figure 5, shows the straight-line course from the port of New York to the port of Liver­pool. The lineA C E Bshows, 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 lineE Brepresents 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.

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