It's been a couple years since I actively hung out on 2M/440 on the boat (mostly day-sailing while getting her ready for the big departure..:-) but I do recall
finding a number of "pro" fishing
boats hanging out using amateur 2M & 440 as a "secret channel" - almost every big boat that took fishing
passengers out of San Diego
seemed to have an amateur dual-bander installed on the bridge. No, they weren't interested in talking to actual amateurs, nor did they have anything resembling an amateur callsign. I've also caught them on other folks' HF channels as well.
But I have had a lot of fun talking to shoreside folks along the CA coast - some of them seem amazed that boats could access their repeater which was 30-40 miles inland!