Eagle FISHMARK 640C, Installation And Operation Instructions Manual

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For example, some (but not all) manufacturers use a layer of fiberglass,
then a core of balsa wood, finishing with an outer layer of fiberglass. Re-
moving the inner layer of fiberglass and the balsa wood core exposes the
outer layer of fiberglass. The transducer can then be epoxied directly to
the outer layer of fiberglass. After the epoxy cures for 24 hours, fill the
remaining space with polyester resin. When the job is finished, the hull
is watertight and structurally sound. Remember, the sonar signal must
pass through
solid fiberglass. Any air bubbles in the fiberglass or the ep-
oxy will reduce or eliminate the sonar signals.
Testing Determines Best Location
Ideally, the shoot-thru transducer should be installed as close to the
transom as possible, close to the centerline. This will give you the best
performance during high speed maneuvers.
Shoot-thru-hull transducer locations for
high speed or trolling speed operation.
To choose the proper location for shoot-thru-hull mounting, follow these
testing procedures: (You may need a helper to complete these steps.)
1. Anchor the boat in about 30 feet of water. Add a little water to the
sump of the boat. Plug the transducer into the sonar unit, turn it on, then
hold the transducer over the side of the boat in the water. Adjust the sen-
sitivity and range controls until a second bottom echo is seen on the dis-
play. You'll need to turn off Auto Sensitivity, Auto Depth Range and
ASP

. Try a range setting that is two to three times the water depth. The
Transducer location
(trolling speed)
Transducer location
(high speed)