Hi all
excerpt from my fishfinder gps manual.
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 installation
(often called simply "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 operation
and good to excellent depth capability. There is no possibility of
transducer damage from floating objects, as there is with a transommounted
transducer. A transducer mounted inside the hull can't be
knocked off when docking or loading on a 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
on your sonar display. (This is not an issue for flasher-style sonars.)
Lack of angle adjustment can be particularly troublesome 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.
Fourth, if your Skimmer transducer has a built in temp sensor, it will
only show the temperature of the bilge, not the water surface temp.
Follow the testing procedures listed in the shoot-thru-hull installation
section at the end of this lesson to determine if you can satisfactorily
shoot through the hull.
It also states the use of epoxy and shows the transducer mounted in a cavity secured by a small film of epoxy then flooded around the transducer with epoxy. thus making a sealed block similar in construction to the actual transducer itself.
I am in the proces of ordering a new transducer for my finder as the other unit is firmly fixed to my other toy.
will have a play as i now you can get suction cup support fixings for the transducers and that is going to be my first go, cheap and simple and can easilly be removed or relocated.
hope this helps aswell.