Humminbird CHIRP Installation Manual page 24

NOTE: If you need to limit the length of the bolts entering the Radar scanner base, use appropriate
risers (shims) or additional washers.
6. Hand-tighten the bolts to a torque of 11 ft·lbf (15 Nm).
CAUTION! Do not use a high speed driver on this combination of fasteners. Hand-tighten only.
Installation
Mounting the Scanner Unit
mounting surface
(partial view)
flat washer
spring washer
bolt
16