Transducer testing
For temporary testing just fill a zip lock bag with water and put the bag between the transducer and the hull. I used silicone to mount the transducer temporarily, later I found that the spot I used had too much noise, so I moved it. It's still in the silicon 3 years later. Yet another method is to stick it to the hull with bees wax, easily and cheaply available in the form of toilet bowl wax. Some people have left the transducer in the wax for years also. Hope this helps. Peter