Raytheon HSB L755, Owner'S Handbook Manual

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2-8 HSB Series L755 and L760 Fishfinder
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• On a boat with a fiberglass hull, the leading edge of the transducer should
extend 1/8" (3.2 mm) to 1/4" (6 mm) below the bottom edge of the hull as
shown in Figure 2-5. On an aluminium hull, the transducer should extend
a bit more – 1/4" (6 mm) to 3/8" (9 mm)
• If the boat will be trailered, be sure the transducer will not hit any rollers,
bunks or fittings on the trailer.
Figure 2-5: Transom Mount Transducer - Vertical Position
Thru-hull Transducer
Figure 2-6 shows the best transducer location for different hull types.
• Displacement hull powerboat – Locate at 1/3 aft load waterline length
(LWL) and 6 - 12" (150-300 mm) off the centerline on the side of the hull
where the propeller is moving downward.
• Planing hull powerboat – Mount well aft, on or near the centerline, and
well inboard of the first set of lifting strakes to ensure that it is in contact
with the water at high speeds. Mount on the side of the hull where the pro-
peller is moving downward.
Outboard and I/O – Mount just forward of the engine(s).
Inboard – mount well forward of the propellor(s) and shaft(s).
Step-hull – Mount just ahead of the first step.
Boats capable of speeds above 25 kn (29 m.p.h.) – Review transducer
location and operating results of similar boats before proceeding.
No! No! No!
Average transom angle -
no wedge necessary Vertical transom -
place wedge this way Sloping transom -
place wedge this way
2˚ to 5˚ 2˚ to 5˚
For fibreglass hull – 3.2 to 6 mm (1/8 to 1/4 in)
For aluminium hull – 6 to 9 mm (1/4 to 3/8 in)
The bow of the transducer
is above the bottom of the
transom, creating cavitation. Rivets on the hull are
creating bubbles. Lower
the transducer a bit. The rear of the transducer
is too high, creating
cavitation.
D4873-1
2˚ to 5˚