Raymarine DSM300 Install Manual page 33

Chapter 2: Transducer Installation
Outboard and I/O – Mount just forward of the engine(s).
Inboard – mount well forward of the propeller(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.
• Fin keel sailboats – Mount to the side of the centerline and forward of the fin
keel 1 - 2 ft (300-600 mm).
• Full keel sailboats – Locate amidships and away from the keel at the point of
minimum deadrise angle.
• Fiberglass Hulls – Since the hull absorbs acoustic energy, transmitting through
the hull reduces the sensor's performance. Fiberglass hulls are often rein-
forced in places for added strength. These cored areas contain balsa wood or
structural foam, which are poor sound conductors. If you cannot avoid locat-
ing the sensor over coring, follow the instructions for "Installation in a Cored
Fiberglass Hull" on page 55.
• Thru-hull Transducer Headroom– Allow adequate headroom inside the vessel
for the height of the thru-hull housing, tightening the nuts and removing the
insert. The minimum headrooms are:
With fairing: 10" (254 mm)
Without fairing: 12" (305 mm)
• In-hull Transducer – Find a location where the fiberglass is solid:
There are no air bubbles trapped in the fiberglass resin.
There is no coring, flotation material, or dead air space sandwiched between
the inside skin and the outer skin of the hull.
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