Scottboy,
i am a 1/4 share owner of a young 88 (apporx 30ft). it is a fantastic arrangement as the other guys are more into racing it, so it is often available for my family day cruises & living just 5mins away it is a no-brainer.
We have a "floating fund" - cant call it a sinking fund for a boat ! - where we all put in a couple of hundred each month to cover all costs - this builds up over time to buy sails cover the biger maintenance programmes. We have the occasional working bee days & everyone appreciates the need to leave it clean & tidy after each use. Board meetings are held occasionaly, usually in a balmain pub where we discuss the racing calander, maintenance etc. - it i important someone takes notes, as no one can remember much at the end.
I think it is important that everyone is on the same page with understanding what is expected from each other. I have known these guys for many, many years I have previously co-owned 2 ski boats with 2 of the guys, and raced skiffs & yachts with one of them for about 20 years and one of the others for about 5. we have a lot of sailing miles together under our belts and so a high level of trust between us.
I dont think i would regard a boat as a "sound investment" but our arrangement provides a sensible way to own and keep a boat, without having to tear up too much money.
anyway that is my experience & 20c worth.
cheers