Cruise Planning Questionnaire

    Vehicle(s) required:
    Name of ship for ROV ops:
    Ch Sci:
D. Fornari and J. Cochran
WHOI, G&G Dept. MS#24
Woods Hole, MA 02543

Lamont-Doherty Earth Obs.
Rt. 9W
Palisades, NY 10964
508-289-2857 914-365-8396
    POC / contact info:
Departure port & date:27 Jan 2000
    Distance to first station:
    Number of stations:
    Distance between stations:
    Total days on station:
5 Alvin Dives
Arrival port & date:9 Feb. 2000
Op area:EPR crest 935-38'N
Lat/Lon:9 35'-38'N 104 15'-16'W
Depth range:2500-3000 m
    Will the vessel be operating within 200 NM of a foreign country?
    Which country?
    Are visas or special travel documents required?

Funding agency:

Grant or contract number: OCE-9912072

    Science objectives/activities planned:
The primary purpose of the 5 Alvin dives to the EPR crest will be to conduct
near-bottom geophysical traverses across the ridge axis along E-W lines that
are spaced about 100m apart, using the NAVO Bell BGM-3 gravimeter in
the Alvin sphere. The field area is the site of a small overlapping spreading
center where we believe that we have the best chance of imaging the
distribution and continuity of individual dike swarms that underlie the axial
summit trough in this region. This could provide a very new and important
understanding of the volcanic emplacement and eruption processes at the
mid-ocean ridge. The gravimeter installation in Alvin has been carried out a
few times in the past and the various requirements for electrical and data
inputs/outputs are basically familiar to the at-sea ops group and the shore
based DSG. The meter has been sniff tested.

Navigation is essential to the data acquisition and analysis program.
Dana Yoerger has agreed to assist with the integration of a DSL doppler on
Alvin to help refine the LBL navigation. The basic plan for LBL will be to
deploy approximately 6 transponders, in a network that covers an area
spanning about 3 minutes of latitude from 9 35 N to 9 38 N. We tentative
plan to deploy the transponders in a line west of the ridge axis, but are open
to alternate plans. Details of the dive plan and the navigation scheme will be
discussed at a meeting with Dana and DSG with a Seabeam map of the area.

In addition to the primary acquisition of near-bottom gravity data, we
need to have better point to point pressure depth data recorded at 1 sec
intervals (the same acquisition rate for the gravity data), and 1 sec data from
the suite of Alvin attitude sensors. It is critical that the gravity data be
recorded and time stamped with the same time as all the attitude data. In
1994, we attempted this but there was a fundamental problem with an
emulator program used on the Alvin datalogging computer to record the
gravity data that was not synched to the Alvin time base. We will need to be
sure that we have fully discussed and resolved these issues well prior to the
cruise so that none of the past problems recur as they very negatively impact
the processing and interpretation of the geophysical data.

One other critical aspect of the program is the sub s trim and
autopilot controls during the traverses. We plan to travel over the seafloor at
about 5 to 7 m altitude, and try to maintain a constant altitude over the
bottom with as few vertical excursions as possible as they dramatically
impact the accelerations recorded in the gravity data. We will generally not
be stopping for samples during the dives, other than perhaps at the start and
end, when we will sit on the bottom to stabilize the meter as pre- and post-
traverse checks on data quality. So the dives will entail a lot of driving with
the requirement that the pilot try to maintain the sub s track and altitude
accurately in order to run the prescribed survey lines. In addition, we may
do one control line where we put markers on the bottom and sit and acquire
gravity for 5 minutes at each site, and then fly over the same locations
collecting data. This has been done to excellent effect previously (Cochran
et al., 1999) in our 1994 experiment and serves to provide a quantitative
control on data precision and accuracy.
Is there any way to better control Alvin s path through the water to
minimize the porpoising we ve seen in the past? I suspect that perhaps the
trim and ballasting of the sub is critical in this respect. Please let us know
about this.

WHOI shipboard scientific instrumentation desired:
    12 kHz Transducer
    3.5 kHz Transducers
Chest Freezer
-70 Deg Freezer
    Rock Dredge
Pinger for Wire Use

Is nighttime work anticipated on this cruise?

    Critical MET sensors:
    Critical CTD sensors:

Do you need Seabeam? (AT and KN only) Yes

Long baseline (LBL) transponder navigation? Yes No. of xpndrs/nets: 6 transponders
Ultra-short baseline (USBL) navigation?
Doppler/GPS navigation?

Will you be using portable science vans? No How many:

Science Van #1
Science Van #2
Science Van #3

Anticipated standard oceanographic cable use:

Instrument Weight(s)
Maximum Depth
    Conducting hydro
    Steel hydro
rock corer
    Steel trawl
WHOI towed camera
    .681" fiber optic
    Do you require slip rings?
NoNumber of conductors:
    Do you need non-standard wire?
NoIf so, what type?
    Do you need a traction winch?
Will you be bringing any equipment (winches, blocks, etc.) that lowers equipment over the side?

If yes, please provide details:
Will there be special requirements for:

    Electrical power
    Equipment handling
    Inter/intraship communications
    Science stowage

If yes to any of the above, please identify: need to use 120 VAC outlets by Alvin Hanger for towed camera batt.charging

Will any of the following items be used on board?

    Explosive devices
    Portable air compressors
    Flammable gases
    Isotope van

Will hazardous material be used aboard, or deployed by an ROV? No

What measures or plans have been made a) in the event of a spill, and b) for the removal and/or disposal of these materials at the completion of the cruise?

Vehicle equipment required:Check one or both:
Major water samplers
Large capacity slurp samplers
Small capacity slurp samplers
Bio collection boxes
Push corers
Scoop nets
High temperature probe
Low temperature probe
Heat flow probe
Portable CTD
Digital Still Camera
Search Sonar
Profiling Sonar
Rock Drill (Jason only)
Video Duplication (Jason)
    Other vehicle-related equipment (list):
    Science equipment to be installed on vehicle:
see above listing
    Electronic equipment used in the ALVIN personnel sphere:
Bell Gravimeter (already sniff tested)
digital still and video cameras
laptop computer (already sniff tested)
    Other comments and information:
Date Submitted: 10/11/99 01:34 PM