FelixdeCat said..
So these hawkeye things are literally as simple as gluing it somewhere in the hull and pointing it down? It will read through the hull? Forgive my ignorance but if its that easy and cheap I would give it a go. I have always been put off this kind of gear because of the investment required. Does the sensor need to be in full contact with the hull i.e. no air gap?
I have similar to what Cisco has, it's a simple fishfinder/depth sounder mounted in the cabin near the door.
The transducer can be tested for depth before you install it permanently. Simply put it in a plastic bag filled with water and place it level inside the hull where you want to install it. In my Top Hat it's forward of the front bulkhead a little to Starboard under the v-birth. This places it away from the keel. Set the face of the transducer level, then turn on the unit.
To check the depth, just drop a sinker line to the bottom and measure the line to the height of the transducer. It should be close.
If the depth reading on the unit is close enough to the sinker line, you can use silicone or, as I did, Epoxy glue. Clean the hull carefully with metho, then just glue it in place, making sure there are no air bubbles in the glue/silicone, as that will effect the readings. All it really needs is a (not too thick), airless medium to sit in, that allows the clicks to go through and be heard.
My transducer is about 400mm lower than the waterline. My keel is 1.4m from the water line, so I set the depth alarm for 1.6m, just to give me time to back out if it goes off. It's been in place for about 5 years now and the only thing it doesn't give me is water temp. Not that that's a problem.
