My concern about a dry slip is that it is like buying a condo... the investment is very dependent on the management. Granted, many of these have shown appreciation, but what is the current market? For an easily trailerable boat, I'd have to think twice about paying large bucks for a dry slip. In areas where the ramp availability has gone away due to marinas selling out, I can see where this may be a solution... but are people putting a $20k boat into a $50-100k dry slip? With a boat that you can't trailer home at the end of the day, this may be one of the few options in some areas.
What are the maintenance fees? How is insurance handled? And do you get the current market price of the slip back if there is a catastrophic loss (such as a hurricane or fire), or just your initial investment... and how is that value determined? Hours of operation? What happens with your slip if your boat isn't in it? (Some marinas don't allow sub-letting) Who gets that income if you can sub-let? Split? How are taxes handled? Will there be a fund for capital expenditures to handle repairs/upkeep or will there be special assessments? When you decide to sell, can you do that independently or do you have to use their service/broker?
My personal opinion is that these are interesting investments for the party doing the original building/selling - they are selling "air" with some structure. For that amount of money, you could buy land and build a small boat garage. Of course, you don't have someone putting the boat in and out for you.
Lots of considerations.
Best wishes,
Jim B.