My only experience is exchange of services for use. This grew out of race crewing and my realizing NOBODY was taking care of the boat, it looked worse every time we were aboard, and the elderly owner was paying through the nose for work that was questionable at best, and almost always delayed or not completed.
I'm anal about the boat. I just started taking care of the obvious - cleaning, waxing, disposing of broken down and abandoned gear from the previous owner, new deck lines
, etc. Now the owner's face lights
up every race night, and he basically says 'you'd do that too' when I tell him not to worry, it will be taken care of. I do have 22 yrs of building and service, still have contacts in the industry for parts and advice too.
Owner can no longer handle boat by himself, boat maintenance is my therapy, and owner regularly reminds me that we can take the boat anywhere, any time, as long as we have it back by 5pm race night. A sweet, no-strings-attached arrangement that the rest of the crew has no interest in taking part in. SWEET!