Putting Boat On The Hard vs. 6 Months Of Ownership

What you are proposing is very practical with some tweaks. Like Pascal said allow for more time for downtime and travel. A boat is a very personal thing for me. I don’t want someone else involved in the operation and management. It can work with the right people but imagine if I one person is a lousy skipper and runs it aground and then the other party has to split that bill. That is just one of many things that I can see leading to arguments. It can work but it is not for me.

Sounds interesting. Some thoughts come to mind:
1. Presumably both parties will be paying cash. Any loan would make things really complicated, especially if one party falls on hard times.
2. Speaking of hard times, need to figure it's a possibility that one party won't be able to pay dockage/maintenance if "it" hits the fan, so need to plan on worst case to see if one party can afford to float the other's share, presumably with a deduction from sales price (perhaps with interest) upon sale if not repaid sooner.
3. Assume each party will be responsible for their own dockage? What about cleaning (hull and bottom), mechanical, etc. Unlikely that each location charges the same amount for these items. Assume you'll share 50-50 regardless of location (perhaps with the exception of dockage), but need to figure out in advance. What about if the boat is damaged though (whether or not through negligence of one party)?
4. Agree in advance on what sorts of things require joint approval in advance. Don't want to be in a situation where one guy does something (like adds a new gadget) and expects 50% reimbursement even if the other guy didn't want or approve it.
5. Figure out how often will you true-up the joint expenses.
6. Make sure you get insurance for both owners and both locations. Both marinas will likely insist on being additional insureds on the policy. Also make sure the transport captain is covered if you're using a captain to transport the boat.
7. Probably a good idea to figure out in advance how to handle if one guy wants out. Is there a minimum period before either guy can trigger a sale? Who picks broker? What location will be used for the sale? Will the other guy have a right of first offer or right of first refusal?
8. Any adjustment for hours of usage? From personal experience this is kind of tough to keep track of, but if one side will run the boat a lot more than the other it's something to at least think about.
9. Given fuel cost it may make sense to agree on whether the boat gets filled before transport and who pays. Presumably each side pays their own fuel usage.

That's it for now. Probably missing a bunch but it's something. Seems like a great way to own a nice boat at a much lower cost. Good luck!

OR;
Just charter a boat that meats your schedule and there is no issues. Boat ready to go per schedule and nothing left behind from previous tenant.
No investments, just a rental.

Captain Ralph is very, very correct
I have owned a yacht for more than 40 years, of which 25 years with a partner,
I will not be able to tell you all the plots and problems of the partnerships (some of it were mentioned by LuvBigBoats) , it would require a very thick book
For the past 15 years I have owned a yacht by myself and the picture has changed to wonders,.
- The yacht is a second home and I travel to it with only a wallet and a computer, all my staff is onboard.
- The yacht, at the moment, is a two-hour flight away and within 4 hours I am from the door of my house to the door of the yacht
- I sail several times a year, whenever it's convenient for me and I don't need to coordinate with anyone.
- I am the only one who determines when to maintain it according to my convenience
And these are only the main advantages
From my experience and my age, I'll recommend that you find a way where you will be the sole owner of the house

So based on your last sentence, it sounds like this is something you're moving forward with. They'll be a lot of people waiting on your report.

I don't personally know of any boat share arrangements, but it's common for small planes. Small plane operating agreements might be a good start for your situation.

I tried the boat partnership with a good friend. All went well as long as we were fishing. Then my good friend got into diving.
I went along to operate and hold boat up on dive spots. Boring! Boat was in my home slip for free and most maintenance was done by me because I was available. Any way we remained friends and sold the boat. We both bought boats to our liking. I wouldn't recommend a boat partnership, unless it is a profitable business.

Back when I was in High School my folks bought a 1/4 share in a boat. The idea was each partner had a set week each month. This was in So Cal so you can virtually boat year round. You can predict the outcome I’m sure. Most of our weeks were repairing, maintaining, cleaning and fueling. Somehow we were the only partners that knew how to do these things. I believe the deal fell apart in 6 months.
First house I bought was a weekend get away in partnership with a very good friend. We had very different ideas on repairs, cleanliness, etc. 1.5 years into it I asked him to buy me out. We didn’t become mortal enemies but relationship was never close again.
Almost everyone has similar stories of some sort with similar ending. Everyone thinks their deal is structured better, relationship is stronger, blah , blah. For me, if there is any reason that a partnership is needed, desired or seems to make sense, I don’t need it. My only partner is and will forever be, my wife!!