Humminbird 1158c Combo Installation And Operation Manual page 34

1. Locating the Transducer Mounting Location
NOTE: If transom mounting is not possible because of a stepped hull or cavitation noise, trolling motor
installation may be an option. See Trolling Motor Transducer Installation for more information.
1. First, determine the best location on the transom to install the transducer. Consider the
following to find the best location:
Deadrise Angle
• The best way to locate turbulence-free water is to view the transom while the boat is
moving. This method is recommended if maximum high-speed operation is a high
priority. If this is not possible, select a location on the transom where the hull forward of
this location is smooth, flat and free of protrusions or ribs.
• The hydrodynamic shape of your transducer allows it to point straight down without
deadrise adjustment.
• On boats with stepped hulls, it may be possible to mount the transducer on the step.
Do not mount the transducer on the transom behind a step to avoid popping the
transducer out of the water at higher speeds; the transducer must remain in the water
for the control head to maintain the sonar signal.
• If the transom is behind the propeller(s), it may be impossible to find an area clear from
turbulence, and a different mounting technique or transducer type should be considered
(see Trolling Motor Transducer Installation).
• The Side Imaging transducer must NOT have anything obstructing the 'view' of the side
looking beams, i.e. nothing can be in the line of sight of these beams (not a hull, motor,
or other transducer, etc).
Transom Mount - Side Imaging®
• It is very important to locate the transducer in
an area which is relatively free of turbulent
water. As a boat moves through the water,
turbulence is generated by the weight of the
boat, and the thrust of the propeller(s) - either
clockwise or counter-clockwise. This turbulent
water is normally confined to areas immediately
aft of ribs, strakes or rows of rivets on the
bottom of the boat, and in the immediate area
of the propeller(s). Clockwise propellers create
more turbulence on the port side. On outboard
or inboard/outboard boats, it is best to locate
the transducer at least 15" (380 mm) to the side
of the propeller(s).
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