I cut off a piece of 4" plastic pipe about 3" and siliconed it to the bottom (.250) of my new HCM and stuck in a old broken sender added water and a small bag of sand to keep the sender from flopping around and went to the river this week end and the depth finder portion of my Garmin 188C worked like a champ! The max depth of the river I run is 35ft it is glacier feed (looks like coffee with lots of cream) and full of trash. No more broken or kicked up senders for me! I didn't take a picture because I will now get the proper epoxy and make it permanent in the future. I don't know what it would do the sensitivity or max depth in the ocean or do I care. My alarm is set at 2ft as a gentle reminder to grab hold of something and pray.