I would keep it simple:
- if you're not friends, or willing to become friends with the couple, don't bother.
- officially buy the boat from them, and assume responsibility for it on paper - your name on ownership
, marina, etc
a letter of understanding that they will get X days of use per season, and in return they will contribute Y% to the marina fees
, annual maintenance
. Since you're the owner of the boat now, upgrades are your responsibility and cost. It's not fair to stick the old couple for the cost of a new sail or engine
replacement if they have only a few years left to use the boat. Such considerations would have been addressed by the purchase price
This keeps it clean, they have their money
, you have your boat, you both share use. Any other arrangement, like legal
co-ownership just seems more hassle than beneficial. Someone always ends up feeling screwed.