In mounting a transducer through the hull (through-hull), it is important that it is done correctly
because the location of the transducer on the hull will determine how well the entire unit will
perform. There are several factors involved in choosing a good location for a through hull
transducer. In general, powerboats should have the transducer mounted in the last 1/2 - 2/3 of the
hull below the waterline, but always forward of the props and shafts. Make sure the above
guidelines are followed. Sailboats should have the transducer mounted in the first third of the hull
below the waterline, if possible about two feet in front of the keel.
GUIDELINES FOR THROUGH-THE-HULL:
1.
The transducer face must always have a smooth flow of water over the face of the
transmitting surface. Bubbles will cause the instrument to read improperly and report
erroneous readings.
2.
Never mount a transducer in direct line or withing 4 feet behind another through hull fitting,
the keel or rudder, zinc anodes, or other projections that would cause turbulence around the
transducer when the boat is under way.
3.
Never mount a transducer in a recess or cutaway on the hull so that the face of the
transducer is shielded from direct contact with the flow of water.
INSTALLATION: LOW PROFILE TRANSDUCER
Mount the transducer through-the-hull using the following steps:
1.
Drill an 1/8” pilot hole in the preferred transducer location.
2.
Drill an appropriate sized hole through the hull using the pilot hole as a guide.
3.
Have some type of soft backing plate or thin piece of plywood (3-1/2” x 3-1/2” x ½” thick)
available to strengthen the inside of the hull around where the hole was drilled. This serves
the dual purpose of allowing the transducer to conform to the inside of the hull, while
preventing the transducer locknut from unwinding.
4.
Route the transducer cable through the hole in the hull. Do not pull on the cable as this may
cause internal damage to the transducer by causing an internal wiring short and require a
new transducer to be installed.
5.
Apply a good grade of underwater marine sealant (polysulphide compound) to the flange of
the transducer. Use enough sealant so that it beads out around the transducer as you
tighten from inside of the hull.
6.
Put the nut on the transducer from the inside of the hull. If nylon, hand tighten only. If
bronze, tighten with a wrench.
7.
Clean off any excess sealant from around the transducer.
INSTALLATION:
THROUGH-THE-HULL TRANSDUCERS
9
IMPORTANT: AFTER LAUNCHING THE BOAT, BE CERTAIN TO CHECK THE TRANSDUCER
LOCATION FOR LEAKS.
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