Humminbird 981 manual Without deadrise adjustment, Not a hull, motor, or other transducer, etc

98x_Manual_531376-1_A.qxd 2/23/2005 11:39 AM Page 19

1.First, determine the best location on the transom to install the transducer. Consider the following to find the best location:

• 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

To mount the transducer bracket to the boat:

1.Remove the transducer mounting template from this manual. See Appendix A for the Transducer Mounting Template.

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).

• 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

Level	15” (380 mm)
	from prop(s)

2.Hold the template on the transom of the boat in the location where the transducer will be installed. Align the template vertically, matching the lower edge of the transom with the bottom corner of the template. If your propeller moves clockwise as the boat moves forward, mount the transducer on the starboard side, and use the bottom left corner of the template. If your propeller moves counter- clockwise as the boat moves forward, mount the transducer on the port side, and use the bottom right corner of the template.

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).

3.Using a pencil or punch, mark the three mounting holes on the transom. Do not mark or drill any other holes at this time.

4.Using a 5/32" (4.0 mm) bit, drill the three holes to a depth of approximately 1" (25 mm). On fiberglass hulls, it is best to use progressively larger drill bits to reduce the chance of chipping or flaking the outer coating. Use a marine-grade silicone sealant to fill the drilled holes.

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