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to loosen the screws and slide the transducer up or down.) If you fre-
quently lose bottom signal lock while running at high speed, the trans-
ducer may be coming out of the water as you cross waves or wakes.
Move the transducer a little lower to help prevent this.
If you cruise or fish around lots of structure and cover, your transducer
may be frequently kicking up from object strikes. If you wish, you may
move the transducer a little higher for more protection.
There are two extremes you should avoid. Never let the edge of the
mounting bracket extend below the bottom of the hull. Never let the
bottom – the face – of the transducer rise above the bottom of the hull.
Shoot-Thru-Hull vs. Transom Mounting
In a shoot-thru-hull installation, the transducer is bonded to the inside
of the hull with epoxy. The sonar "ping" signal actually passes through
the hull and into the water. This differs from a bolt-thru-hull installa-
tion (often called "thru-hull"). In that case, a hole is cut in the hull and a
specially designed transducer is mounted through the hull with a
threaded shaft and nut. This puts the transducer in direct contact with
the water.
Typically, shoot-thru-hull installations give excellent high speed opera-
tion and good to excellent depth capability.
There is no possibility of damage from floating objects. It can't be
knocked off when docking or loading on the trailer.
However, the shoot-thru-hull installation does have its drawbacks.
First, some loss of sensitivity does occur, even on the best hulls. This
varies from hull to hull, even from different installations on the same
hull. This is caused by differences in hull lay-up and construction.
Second, the transducer angle cannot be adjusted for the best fish
arches. This can be a problem on hulls that sit with the bow high when
at rest or at slow trolling speeds.
Third, a transducer CAN NOT shoot through wood and metal hulls.
Those hulls require either a transom mount or a thru-hull installation.
