When the Appalachian Mountain Club board of directors announced earlier this month it would vote on a proposal to sell the Fire Island Cabin, a volunteer-run recreation facility in Atlantique, it took members of the club’s New York-New Jersey branch by surprise. So many protested the sale that the AMC headquarters instead delayed the vote for a year for further consideration. The group had originally proposed the sale because of concerns about the residential neighborhood and rising seas, and to free up money to be invested elsewhere.