I have successfully done this three times; however, only with fiberglass
hulls but not aluminum
I have never been a fan of drilling through my hull
to place a transducer.
In all cases I purchased a clear plexiglass tube approximately 6" in diameter and approximately 8 - 10" in length. I shaped one end of the tube to the contour of the inside of the hull, off the center line away from the keel
. Once the tube meets the contour I used silicone to hold it in place and seal it to the hull. With a flat piece of clear plexiglass I fabricated a cover.
Suspend the transducer from the cover (drill a hole through the cover and use the supplied nut from the transducer) so the transducer is close to the hull. Fill the tube with water
and you're in business.
By using clear plexiglass you can always check to see that your tube if full. The set-up works well and my depth
sounders never let me down, i.e. never ran aground. The manufacturers will tell you that you will lose sensitivity and that may be more so with an aluminum
hull. Also, you may choose to use another fluid like baby oil
instead of water
since the transduce sensitivity decreases as the density of the media changes.