That looks like the Weymouth town ramp to me !!!
In the Past, I kept my boat at Tern Harbor down the street from there, and when I had time to kill, I would sit at the ramp and watch things like that all the time!!!
They have a big sign there that says (is the plug in ? )
Not too many people read it though!!!
At the end of the season when most the marinas require you to haul out, I have been there and made some $$$
Lots of unskilled people who can't get boats on trailers , nor can they back a trailer down a ramp!!!
Ronnie