Excellent Yacht Partnership Book
Back in 1981 Dexter and Paula Odin wrote a short book entitled Yachtsman's Legal Guide To Co-Ownership. Odin is a practicing attorney in the Maryland area (at least he was practicing when I hunted him down about two years ago). The book is well written with a thorough explanation of the many clauses within the co-ownership agreement. While the book is now over 25 years old (and lacks some more recent legal structures such as an LLC), it is nevertheless a great source for structuring a group ownership with a focus on boating. The ISBN is 0-8286-0087-0 and possibly could be found by doing a Google search. The slant of the book is one of "comradship" but guided by a well-structured legal document.
Here is an example of the document with paragraph 1 under PURPOSE: "With implicit trust in each other, a common appreciation of the sea, and a desire to unite in the ownership of a pleasure yacht, we enter into this Agreement to provide a better understanding of our mutual expectations and a greater awareness of our fiducial obligations to one another."