Not only is the Sperry Gy­ro-Com­pass unaf­fec­ted by mag­ne­tic con­di­tions, re­sult­ing from the heel­ing error, but before being placed upon the ship it is tested for days under con­di­tions sim­u­lat­ing the mo­tion of the ship in the most severe storm.

A ship steered by the Gyro-Compass trav­erses a straight line course; the Gyro-Com­pass does not os­cil­late with the rol­ling of the ship. It is not nec­es­sary for the helms­man to use as much helm to keep the ship on her course. A great saving is made in the use of the steering engine.

There is no “lag” in the Sper­ry Gy­ro-Com­pass, be­cause it does not leave the mer­i­dian, no mat­ter which way or how quick­ly the ship may turn or zig-zag. Ex­haus­tive tests have been con­duct­ed on com­pas­ses installed on torpedo boat des­troy­ers. Even when zig-zag­ging at top speed in heavy seas the Gy­ro-Com­pass shows no “lag.”

Trav­e­ling the straight line course instead of the sin­u­ous course, ships equipped with the Sper­ry Gy­ro-Com­pass have saved from one to ten per cent in time over the average sched­ule time re­quired to cov­er their courses when steering by the mag­ne­tic com­pass.

The Savannah, first steamship to cross the ocean.

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.