Subsurface moorings are just that: moorings which do not
break the sea surface. They are designed to position each
sensor at a specific depth. Scroll down to see the top of
this mooring... it starts at 20 meters above bottom.
A steel float keeps the mooring upright.
Stainless steel chain is used as a damper below the float.
A small tube trap catches sediments which fall through the
water column. These are often used as controls for other traps
on the same mooring.
An Anderson Trap catches greater
amounts of sediment with a larger opening. The sediment accumulates
in layers in a tube below the funnel.
Plastic jacketed wire rope offers a lightweight, low drag
alternative to chain for connecting mooring components together.
A Vector Measuring Current Meter is
set to record currents at 10 meters above the bottom. Attached
to it is a Sea Cat data logger which measures temperature
and salinity, and records turbidity levels sensed by a Sea
Another tube trap is attached closer to the sea bed to compare
the sediments in this part of the water column with those
caught by the traps above.
A nylon bridle is used instead of wire at this point to minimize
the introduction of foreign matter into the trap below.
A Honjo time series trap works just like the Anderson 10
meters above, except sediment is collected in bottles, rather
than a tube. A computer and motor rotate the sample bottles
so that scientists know exactly how much sediment was collected
in a given time period. Attached to the Honjo trap's titanium
frame are two acoustic releases (one is a backup). When given
an acoustic command from the surface, the release lets go
of the chain that attaches the mooring to the anchor below,
and the entire mooring rises to the surface to be recovered
by a ship.
This mooring's anchor weighs 2200 pounds.