Raymarine DSM300 Install Manual page 45

Chapter 2: Transducer Installation
Figure 2-15: Fore View of Transducer Installation
8. If a fairing is used, apply marine sealant to the flat side of the triangular plug.
Push the plug into the triangular recess in the fairing. The triangular plug fits
one way only. Be sure the curved side of the plug is exposed, matching the
curve on the outside of the fairing. Tap it into place with a mallet.
CAUTION:
For smooth water flow over the transducer's sensor, be sure that
the external surface of the installed triangular plug is FLUSH with
the external curved surface of the fairing.
9. Being sure the valve assembly is seated firmly in the housing, carefully screw
the cap nut in place. Hand tighten it only;
10. Remove any excess sealant on the outside of the hull to ensure smooth water
flow over the transducer.
do not over tighten
.
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