Navigation and Seamanship

2.2.7. Parts bearing circle

                                                                          

Ring : Fits upon a 7 ½ inch gyro repeater or magnetic compass

Sight Vanes : Allow the observer to take bearings of objects by aligning the two vanes to the object. The near vane contains a peep sight while the far vane contains a vertical wire. The far vane is mounted on top of a housing that contains a reflective mirror inside enabling the observer to read the bearing from the reflected portion of the compass card

Reflector Vane : Allow the observer to observe azimuths of celestial bodies (stars and planets) at various altitudes by picking up their reflection in the black mirror. When the body is observed, its reflection appears behind the vertical wire in the far vane.

Levels: Indicate if the ring is level with the horizon. NOTE:Bearings read when the ring is not level are inaccurate

Concave Mirror: Reflects the Sun’s rays onto the prism housing on the other side of the ring when the observer is taking an azimuth of the Sun.

Prism Housing : Directs the beam of light from the concave mirror downward in a narrow beam onto the compass card enabling the observer to read the azimuth to the Sun.