new fishfinder xducer question?

[Bushwacker]

In mid-late 70/s I had an ancient Apelco/Raytheon flasher/recorder type on my Seafari with the sender mounted in block glued to inside of hull with silicone, about 1' fwd of transom. Worked fine as long as there was water in block between sender and hull. Have heard of the same thing being done using large PVC pipe filled with glycerin. It probably did lose some depth capability as it would not read much over 100' and it was supposed to be good for 60 fathoms. But it was fine for locating the reefs I was looking for, and more reliable than current transom mount that wants to kick up after a high speed run! Have had a tough time getting it tight enough to stop that.