Raymarine GPS 11 User Manual page 13

Apelco GPS11 Installation and Operation Handbook
10
2.2.2 Fixed to a horizontal surface
The bracket may be fixed such that it may be adjusted vertically
only or such that it may be rotated and adjusted vertically.
For vertical adjustment only screw the backplate (1) to the desired
horizontal surface and then secure the main bracket (2) at the
desired angle using the finger bolt (3).
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