HOT-24: Chief Scientist Report

Chief Scientist: D. KARL

Personnel List

David M. Karl, Chief Scientist
Dale Hebel
Ricardo Letelier
John Dore
Terrence Houlihan
Marc Rosen
Luigi Possi
Jef Snyder
Toshiaki Shinoda
Chris Sabine
Fernando Santiago-Mandujano
Dan Sadler



Summary

A  summary of some of the problems during Hot-24 aboard the Alpha
Helix. This cruise was performed in near gale force conditions, 18 ft.
seas and 30 Knt. Winds. As a result, only a fraction of the usual Hot
data was obtained. It can be said here that it was fortunate that
nobody was hurt and little equipment damage occurred.

No operations were performed at night. This was requested the first
night by the scientific watch due to the apprehension of water sampling
on the rear deck and the safety of personnel during CTD recoveries. The
second night operations were going somewhat smoother and it was agreed
upon by the scientific party to attempt working through the night,
however, the captain secured all operations on the back deck after
witnessing his first recovery (one of the better ones) due to safety
reasons.

A total of 7 hydrography casts were made including the deep cast down
to 4500 meters. Duplicate salinity samples were taken on 3 casts for
lab intercomparison. XBT measurements were made on the transit back
with little problems. Meteorological observations were made as
perusal.

Here is a cast by cast summary of the CTD casts.

Kahe point;

Winch failed at 1000 meters during weight cast, one of the hydraulic
hoses blew. Fortunately, ships crew was able to repair it and retrieve
the weight. It was decided at this time to use the Alpha Helix winch
with the single conductor. The change over was to be performed during
transit to station ALOHA, this took about 6 hours.

Station 2 cast 1;

Rosette landed hard on deck during recovery. It was noticed that during
the 1000 meter cast that it was difficult to maintain a minimum of 200
lbs. of tension during decent at a rate of 30 meters/minute. It was
decided to add an additional 200 lbs. of lead on to the rosette.

Station 2 cast 2;

Rosette hit side of ship and A frame violently several times during
recovery. Several bottle spigots were broken of
f but no other damage.

Station 2 casts 3 and 4;

No problems.

Station 2 casts 5;

Lost CTD signal at 1000 meters. This happened when bridge meandered
ship to reduce the 400 meter wire angle. The cast was being performed
with following seas and the ship sailing down wind at approximetely 4
knots. Without any advice or consultation from the CTD lab the bridge
decided to turn the ship into head seas to try and reduce the wire
angle. This caused the CTD to start descending over 60 meters/minute. I
believe the rosette started tumbling at this point and this put stress
on the conductor where it comes out of the hydro cable and is taped to
the rosette frame causing the conductor break.

Station 2 cast 6;

Bad salinity spiking caused by exhaust plumbing being torn from the tie
wrap fastener and kinking, allowing little water to flow. Oxygen is
also noisy. This plumbing malfunction has never happened before. I
believe the problem occurred during the deployment of the rosette with
the ship traveling too fast, thereby causing the package to "skip"
across the water surface. I taped the plumbing more securely to the
rosette frame for the next cast.

Station 2 cast 7;

Deep cast. Again salinity spiking, this time more severe, but no oxygen
spiking. This may be a problem with the conductivity cell. I inspected
the cell after the cast but found no apparent problems with it. I
recommend sending it to Sea Bird for inspection and a calibration. Upon
recovery, three bad kinks were in the sea cable about three meters
above the rosette. I believer this was caused by the package being
passed by the sea cable then pulling tight. CTD signal was maintained
during entire cast.

Recommendations for WOCE hydrographic sampling aboard the Alpha 
Helix.

1)      Not attempting any CTD casts in 25 knots or more of wind due to
	the station keeping abilities of the Alpha Helix. Also seas of
	15 feet or more makes it unsafe for work off the fantail.

2)      A safer, more stable way to deploy and recover the rosette off
	the fan tail, perhaps like the way SIO does with hanging a
	weight below the package. I believe we have all the hardware
	available to do this. This will also allow the package to be
	wheeled off the fantail as much as possible.

3)      The use of the WOCE hydrographic winch. I believe that the
	weight of the 7/16 cable may be too much for our applications,
	unless we put much more additional weight on our package.

4)      Training of ship crew and brdige so they can adapt to our
	needs.

5)      XBT's off of the 02 deck. Waves washing into the fantail can be
	up to your waist, making for a dangerous situation. Also using
	the shipboard thermosalinograph for the SST measurements during
	XBT's.