Yours is a curious question. You are being paid to run a boat, you are hauling cargo, and you DON’T need a license? That doesn’t make sense.
I know that if you have enough money, you can buy an airplane and fly it wherever you like. BUT, you cannot take any passengers, or be paid to do it.
I would assume the law is the same regarding boats. I have always heard that if you are hired to run a vessel for cash, and are carrying cargo (regardless of whether you are paid by the owner of the cargo, or the shipper) you are a commercial vessel, subject to needing a license.
this is like people who started a little ‘ferry’ near me. they stated (after being caught by the CG) that they were charging for the supplies they carried. but the people were being carried for free, so they weren’t carrying passengers for hire. Not that you are carrying passengers, but if you are transporting the company employees, for the completion of their work. then you ARE carrying passengers!
Anyway, get a seatime letter, as deckhand. get a 100 ton license, and don’t worry about it.
After thinking about it, I think you are correct in the assumption that you don’t need a license. BUT, I bet dollars to donuts that this company has little, if any insurance, and is a somewhat less than great place to work, since if they cut expenses to this degree, they probably don’t take care of other conditions too.