3 October 2005
Table 2-2. Examples of Fleet Moorings
a. Vessel Secured at a Single Point
Typical configuration includes the ship deploying a
single drag anchor off the bow. This is usually a
temporary mooring used as a last resort in benign
conditions. A large amount of harbor room is
required for the ship swing watch circle. If the wind
changes direction dramatically then the anchor will
have to reset. Dynamic fishtailing, even under
steady winds and currents, may be a problem.
Putting out a second anchor in what is known as a
Hammerlock mooring may be required in storm
Single Mooring Buoy
A single point mooring (SPM) buoy is secured to
the seafloor typically with 1 to 12 ground legs and
either drag or plate anchors. The ship moors to
the buoy using an anchor chain or hawser. The
vessel weathervanes under the action of forcing,
which helps to reduce the mooring load. This type
of mooring requires much less room than a ship at
anchor because the pivot point is much closer to
the vessel. A vessel at a mooring buoy is much
less prone to fishtailing than a ship at anchor.
Many of the mooring buoys at U.S. Navy facilities
around the world are provided under the U.S.
Navy's Fleet Mooring Program.