My friend has been pulling things apart inside his 80's Adams 40 CC to install a heater. He came across a spot on the hull with some bog around it and dug it open and found this inside. The arrow is pointing towards the bow. Is it an old school depth transponder? What threw us was the fact that it's on the starboard side of the hull near the aft cabin. It's also mounted up the side of the hull, maybe only 30cm or so below the waterline. We were thinking that on a starboard tack, it'd almost be out of the water.