I have been struggling for years to find a place to keep my 17 ft. cat in an area with precious few beaches.
I hate trailering it, so I built a mooring raft that works really well. If you need to haul it for the winter,
you'll need a marina nearby so you can store it boat and raft together.
As a mooring raft it is a dream because it's always into the wind so setting sails is a snap and the raft is so stable it's almost like being on your own personal beach and without the damaging pitching of a moored cat.
Below is a link to pictures and plans for 2 variations of a do it yourself raft.
Or adapt it to your own plan.
http://www.dropbox.com/gallery/69014237/1/Catamaran%20raft?h=10269c