Boats and yachts usually need a boat dock or a mooring. One exception are trailer boats that are stored on a trailer. A water berth is advantageous in that the boat is more easily ready to go. Often the boat mooring is offered as a combined port space. During the season the boat is at its mooring in the water, while in winter the boat comes to a stand on land. There are also boat moorings, consisting only of a stand on land. In this case the boat is lifted by crane into the water from the stand. The berth or mooring in the water can be either a fixed or a floating dock system. Most ports offer guest moorings for visitings boats. These guest berths are usually allocated by the Harbour Master. Normally the boat dock, mooring, or harbor places are rented by the yacht owner. In private marinas, there is also the possibility to purchase a mooring.