A couple of points (some of which are not exclusive to multiple owners).

Amortization 10-12 years. 25% down. Less chance of being upside down.

Partners should have similar philosophies.

Partners should have reasonable expectations about their own use and "rules" set up. Perhaps, number weeks in high time that one could book. Internal "book keeping" of time used (85% of charter rack rate for time booked greater than 90 days, 60% for booking 45-89 days in advance, 40% for time less than 45 days out)... in the end, if similar philosophy of usage, you should likely wind up with similar account balances. Many different ways to set up usage expectation, but do it in advance and thoroughly scrutinize plan.

Define who can use boat owner "time".

Who can authorize discounts to friends/ others (ie, Last minute discounts are smart business. Giving excessive discounts to friends of one owner may "cost" others money)

Each partner should financially be able to afford vessel alone. Helps when revenue down or considering maintenance costs/upgrades that were unexpected.

Having odd number of partners avoids a 50:50 split vote on any issues.But having too any members using boat will negatively affect charter income

Have defined "Out" at end of 5 years, such as boat will be listed with broker X and sold. (Can be amended differently if all parties agree).

Can a partner sell his share? Under what circumstances (ie health issues prevent him/her from using boat).

With many of these points agreed upon, consult a lawyer who may have even more points to add, and get all in writing.

Bottom line, spend more time contemplating the end than the beginning.

Hopefully others can add more/other points to consider.