Accessory to a boat or yacht club, a restaurant serving food and drink; a marine railway for hauling out and launching boats; a boat storage yard; customary accessory structures, including locker houses, storage for spars, sails, outboard motors, tenders and other yachting equipment, but no commercial operations or sale of supplies shall be rendered except such as are incidental and necessary as well as customary in the operation of a yacht and boat club and marina.