You are right in that the beach had been hunted before . . . . I used to live on Brant Lake just a short distance from Schroon Lake and actually went to summer camp there. We used to hunt the beaches on many of the local lakes in the early 70's and were wading / diving in the water by 1975. It was amazing the amount that came off the beaches at that time . . . coins, jewelry and other cool items.
One thing that people sometimes discount is that the equipment that was out in the mid-to-late 1970's had ground balance and discrimination. Not quite what we have today but we were able to get some pretty deep targets with those early VLF units. As far as water hunting, we started by floating control boxes and jury-rigged extension cables with sand / epoxy weights on the coils. Most of what we used was one-off and home-made but it worked (at least until the float flipped or the connections leaked as I can attest to from personal experience)
Lake George was another amazing area to hunt and when we dove the area around the town pier, 20+ silver coins and several gold rings were not unusual from a single dive.
Hate to use that expression as it does make me feel old but . . . :
[attachment 349025 goodolddays.jpg]
Andy