When people hear boat shares, they may think timeshares and run for the hills. Timeshares are typically a horrible investment and some are so bad that you cannot deed them back to the seller or give them away. With timeshares, you typically own one week out of the year of a particular hotel room. You are required to make a large upfront payment and then pay the maintenance fees each year. The maintenance fees are often exorbitant amounts of money relative to what it would cost to just rent the same room for one week out of the year (plus you would avoid having to put any money upfront and wouldn’t be locked into that same room and the same week for years into the future).
Boat shares also require annual fees that cover upkeep, insurance, taxes, etc., but since you are generally dealing with more savvy buyers (not only wealthier but fewer owners — typically 12 instead of 52), they are more careful not to sign off on something stupid relative to the actual costs of owning the boat. Another key difference is that boat shares are often set up to only last a finite amount of time, before the owners agree to sell the boat at its market value. Boats do not last 50+ years like a hotel resort would. Plus since they are held for shorter periods of time, they are less likely to face periodic assessments or large fee increases to remodel like a hotel resort.
That being said, buying fractional ownership of a boat in the form of a boat share is not profitable in an of itself. Look at a company like Bravada Yachts which manufacturers boat and sells them in the form of boat shares. There boat shares are typically just the retail price of a new houseboat divided by 12. The boat starts depreciating from the time you buy it so when it is ultimately sold, it will sell for a lower price obviously. You do avoid the cost of renting of a houseboat, so the idea is that you are lowering your cost of recreation over several years of vacations.
The way that investing in boat shares becomes profitable is in buying someone else’s resale boat share because they’d rather have the money now than pay any more annual fees or wait years for the boat to be sold. The market for resale boat shares is likely to be small or non-existent, and if you are the only viable buyer, you can use the laws of supply and demand to your favor and ask for a favorable price. You can save money on houseboat rentals while you wait for the eventual sale of the boat to occur. If you get the boat share at a low enough price, the sale of the boat years later should yield you a profit, unlike the original boat share owners.