When you pull your boat into a marina, you have the choice of using the fueling slip, the repair slip or the dock. Any discussion of docks and slips comes back to the matter of water: a dock is the water area immediately adjacent to a pier or wharf; a slip refers to water between piers or wharves.
Geography of a Slip
A slip is not as open as a dock. The former is outlined by a pier on each side of the boat, unlike the dock, which has a pier on one side only. A slip can also serve multiple vessels within a single area, the shore-sides of which are lined with piers. The essential characteristic of a slip is that it's open on one end only. It's bounded by land or piers, which shelter the vessels in the slip on three sides to break up swells entering the harbor or marina.
Geography of a Dock
A dock is open on three sides. That is, a boat can move forward, backward or to one side without restriction. While "dock" is frequently used to signify the pier or wharf adjacent to the dock, a dock isn't a structure; it's just a watery location. This openness is critical to many of the functions of a dock: vessels can enter a marina and pull up to a dock to take on passengers, fuel or cargo, and then depart without the added maneuvering required to enter and leave a slip.
Small, single boat slips take up part of the parking of many marinas and a few commercial harbors. The key characteristic is that the boat is either pointed toward the pier or pointed away from the pier, rather than being parked lengthwise, as it would be alongside a dock. The sides of the single slip may be lined with extensions of the pier or the sides of the single-boat slip may be outlined with wooden pilings, driven into the harbor bottom, allowing the boat owner to rig additional lines to hold his craft steady in the center of the slip.
Marina and Harbor Design
A marina's design includes a number of docks and a number of slips. Like the dock, the slip is an area of water with specific characteristics. While docks are used for boat service, such as fueling, as well as for boat parking, slips are often larger, leading to or lined with a variety of docks on either side. Small slips, barely large enough for a single boat, are used for longer term boat parking than most docks, and serviced by a single pier or wharf.
- "The Compact Oxford English Dictionary"; J.A. Simpson, et al.; 1991
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