Subject: write up for SINKEX cruise aboard R/V Revelle
To: shipsked@sio.ucsd.edu
Date: Thu, 5 Nov 1998 08:22:37 -0800 (PST)
Cc: cpm@mpl.ucsd.edu (Christian de Moustier)
MIME-Version: 1.0
SINKEX CRUISE PLAN
R/V Revelle Nov 11-24, 1998
OPERATIONAL OBJECTIVES:
(1) conduct a sidescan sonar survey of the wreck of USS Agerholm
and its debris field, out to about 1 km. The wreck lies in Tanner
Basin in the Southern California borderland at 800 m depth.
(2) retrieve undisturbed sediment samples around the wreck at ranges
of 10 m, 50 m and 1km, for a total of 27 stations. 0.5 m2 of undisturbed
sediment is needed at each station. These samples will be analyzed for
contanimants potentially leaching from the wreck.
APPROACH:
The sidescan survey will be carried out with the Marine Physical
Laboratory's (MPL) Deep Tow Fish 6 instrument package deployed at the
end of a standard 0.68" electro-mechanical tow cable. For this work,
the package will include 110 kHz sidescan sonars, a 4 kHz subbottom
profiler, a 12 kHz long baseline navigation sonar, a 40 kHz obstacle
avoidance sonar, a 150 kHz altimeter sonar, a precision CTD unit, a
compass, and a proton precession magnetometer. Data from all these
sensors are digitized in the Fish and telemetered topside where they
are logged and displayed in real-time on computer monitors and linescan
recorders.
The coring operations will be peformed with a special purpose coring
device developed at MPL and consisting of 3 hydraulically actuated buckets,
18" in diameter, mounted in a heavy steel frame equipped with a video camera
and lights.
The frame will be suspended with a soft thether line below an instrument
interface package deployed at the end of the ship's 0.68" electro-mechanical
tow cable. The package will be equipped with a transponder navigation sonar,
a sector scanning sonar, a down-looking sonar, video recording capabilities
and a module with command and control functions.
In all cases, the bottom will be observed on slow scan television
before landing the coring device, thus minimizing the chances of attempting
to core large boulders or overly rocky terrain.
Samples brought on deck will be partitioned for chemical and biological
analyses.
