Furuno GP-7000F Installation Manual page 13

Thru-hull mounting
Transducer mounting location
The thru-hull mount transducer (520-5PSD, 520-5MSD) provides the best performance of
all, since the transducer protrudes from the hull and the effect of air bubbles and turbulence
near the hull skin is reduced. When the boat has a keel, the transducer should be at least
30 cm away from it. Typical thru-hull mountings are shown in the figure on the next page.
The performance of a sounder is directly related to the mounting location of the transducer,
especially for high-speed cruising. The installation should be planned in advance, keeping
the standard cable length (8 m) and the following factors in mind:
• Air bubbles and turbulence caused by movement of the boat seriously degrade the
sounding capability of the transducer. The transducer should, therefore, be located in a
position where water flow is the smoothest. Noise from the propellers also adversely
affects performance and the transducer should not be mounted nearby. The lifting strakes
are notorious for creating acoustic noise, and these must be avoided by keeping the
transducer inboard of them.
• The transducer must always remain submerged, even when the boat is rolling, pitching or
up on a plane at high speed.
• A practical choice would be somewhere between 1/3 and 1/2 of the boat's length from the
stern. For planing hulls, a practical location is generally rather far astern, so that the
transducer is always in water regardless of the planing attitude.
Thru-hull mount transducer mounting dimensions (millimeters)
22
120 120
28
30
68
68
520-5PSD 520-5MSD
7
24
90 Unit: mm