Though not qualified as a ship, tug and barges can easily be big enough to qualify as a ship in their length and breadth. That being said, they can't turn or stop like a normal power boat. They may take a half of a mile to come to an stop, and may take an 1/8 of a mile for the bow to respond to rudder commands.
Although not strictly relevant to COLREGS it does relate directly to common sense. See below.
since I'm a recreational vessel usually with no particular destination or schedule in mind and he's a commercial vessel trying to get their job done. I'm happy to get out of the way. I don't mind tacking/gybing/heaving-to.
Janet and I were coming South from NY Harbor a couple of years ago rounding Cape May planning to anchor in the Cape Henlopen Harbor of Refuge. See https://activecaptain.com/X.php?lat=...30282&t=n&z=12
. Northbound from well offshore was an ocean-going tug with a long tow. There was lots of time and space so I fire up the radar and tracked him with MARPA. CPA was really close and TCPA was about 45 minutes. I picked up the VHF mic to call when he called me. Golly. I was stand-on both as under sail and on his starboard. The Master was a real gentleman, asked my intentions, and offered to slow down and change course to give way. I told him I was on holiday, in no particular hurry, and respected that he was working for a living; if he would hold course and speed I would be happy to harden up (traveler up, trim jib), slow down (vang on), and take the stern of his tow. There wasn't any other traffic around so we chatted a bit--a nice break for both of us--and both (I think) felt the better for the encounter. We saved him five minutes or so and some fuel, and cost me fifteen minutes at most to anchor down behind the breakwater.
It's good to know the rules and operate within them. There is no substitute for communication and being polite, especially to commercial traffic.