It doesn't bounce around in the mineral oil. The tube fits the transducer
properly. The purpose of this is to allow transducer removal for maintenance
without hauling out, but it isn't for free. Even the best installations
attenuate the the transducer and performance suffers. On commercial ships,
they use a ball valved cavity that works much better.
Steve

wrote in message
ups.com...
Several posts recently about setting transducers in a tube filled with
mineral oil. The problem noted was the mineral oil eating through the
adhesive that affixes the tube to the fiberglass. I found a reference
that stated Sikkens Sikaflex is the adhesive of choice for this
endeavor. I'm going to give this a whirl in the next week. Although I
don't see what keeps the transducer from bouncing around in the mineral
oil.