Thanks for all the replies. What I have in mind is more like renting out the boat half time of the month and we split the monthly expense 50/50. The boat will be a catalina 22 of the 70's vintage, so under $3k value. I'll be the sole owner and I'll take care of all maintenance, so I guess I shouldn't call it a boat partnership really, sorry about the confusion.
I was in something similar last year, except I was the renter. Boat was a catalina 30 and since the owner rarely had time to use it, so he rented it out to 3 individuals, each one gets one week. Owner took care of all maintenace, insurance, etc. We didn't have to buy any equity in the boat, just signed a lease form and pay each month, lease was for 6 months. Sadly, he sold the boat.
So what I want to do is similar to that, except it's just two people. My only concerned is that if he or his guest gets hurt and sues without me being onboard, will I still be liable? Sounds like I will.
Be careful about the "renting out" part of your idea.
I co-own a boat with a good friend who originally introduced me to sailing. I bought a boat and he sold his. After a little while (where we sailed together often), we discussed the idea of a co-owned boat. Neither one of us really wanted to give up sailing, but the costs and time we had to sail was not enough to justify the costs individually.
We bought a boat together, equal ownership, we have insurance that names us both on the policy, and we share all expenses. We have agreed that We will never:
1) Loan the boat to someone else without one of the owners being present
2) Never use the boat for any commercial use (this changes the whole ball game in terms of insurance, boat inspection and certification, etc.).
Our insurance policy will allow our (grown) children or wives to operate the boat (wives never will, but my son took it out once -I have more gray hair for it).
We both have umbrella insurance policies as well to further protect us individually.
Our partnership works well because we like to sail together, although I sail a lot kore than my partner and single-hand 90% of the time. I also do a majority of the work on the boat, but I enjoy that aspect of owning a boat.
I am prepared, if the time ever comes, to buy out my partner, but for now, the partnership works well for us.
Greg