Sharing a boat seems like such a great idea.After all, there are approximately 17 million registered recreational vessels in the United States, but on average a boat is only used a total of 14 days per year. With that amount of usage, sharing only makes sense, right? But purchasing any asset with people you know can create the kind of problems that can end those valued relationships.Dreams of weekends at the boat club and watching everyone's kids grow up together can be replaced with large maintenance expenses, angry calls about who gets which holiday weekend and even possible lawsuits.