Hi Rick, Here is a guess. I heard the transducer that looks like a boat hull (pointy front, square back) does not work as well as the round puck style used for the shoot through the hull applications. If I used the transom mounted style, I was told to build a round berm of silicone sealer, add Squibb mineral oil and carefully embed the pointy end forward with no air bubbles in the oil. That sounded like a major pain, so I ordered a 20 degree round one and it worked fine with the silicone only. That was a while back with an Eagle unit. The info may or may not apply. Did you get the chance to look at Norm Bundek's Sonar installation? album: http://www.msogphotosite.com/M15Sndr.html He is using the boat hull type installed just as you mentioned (of course proving my theory wrong) so he may have some further information. Just to make a point. The same Eagle I mentioned also came with a portable housing and a couple of lantern batteries. I beat the crud out of it and never damaged the transducer. Howard is absolutely right... they are tough! Bill