Ditto Steve's Comments
I echo Steve's comments. Ownership can be expensive given slip fees, maintenance and insurance in addition the the capital investment in the boat and the time it takes to take care of a boat. Obviously the total per usage cost comes down the more you use an owned boat but I would bet that any usage scenario short of living on your boat, ownership would be more expensive economically. However, I would also bet that many owners derive much pleasure from maintaining their boat (most tasks anyway, but not all), personalizing their boat and knowing that they can go where ever, when ever they want to go. I would also bet that many boat owners actually charter in other venues as the need arises. The answer to your question realy lies in how you define "expense". If you're looking at pure economics - charter is probably cheaper onver the long run - but if you're including personal satisfaction aspects of ownership, ownership is usually more satisfying...most of the time.