HOT-29: Chief Scientist Report
Chief Scientist: D. HEBEL
Personnel List
Dale Hebel, Chief Scientist
Ricardo Letelier
Terrence Houlihan
Jef Snyder
Jim Christian
Katharina Thywissen
Chris Carrillo
Dan Sadler
Fernando Santiago-Mandujano
Sean Kennan
Soma
John Constantinou
Summary
HOT 29 was conducted aboard the RV Alpha Helix 8-12 August 1991. All
samples and hydrographic work was completed with no major
mechanical/instrumental failures with the exception of the weak to
nonexistent RDF transmissions from the in situ array (channel 72). The
only persistent problem which plagued HOT 29 was leaky water bottles.
Apparently, the springs had been replaced prior to departure. The
spring tension was sufficient to seal the bottle until the vent value
was opened. Obviously, adequate spring tension is necessary to offset
the contained water sample weight. The specifications for spring
tension should be available from the bottle manufacturer and we should
adjust our bottle spring tension to this value and test the bottles
before HOT 30 departure.
HOT 29 departed Snug Harbor on 8 August 1991 at approximately 0900
hrs. While steaming to Kahe Pt. a fire and boat drill was conducted by
the First Mate (Bill Rook), followed by a cruise objective and safety
science meeting led by D. Hebel. It was pointed out by Bill that in
addition to life vests, hard hats were required (for insurance coverage
to be effective), when deploying overhead equipment. This point has
been raised on previous Helix cruises, however, it is not ship's policy
to require hard hats in the same regard as they require life vests and
no Chief Scientist has made this policy for scientific personnel. I
asked if CTD deployment fell into this category and Bill responded that
it did. I therefore suggested to the science party that we wear hard
hats during CTD deployments as well as Trap and in situ array
deployments/retrievals. This action was only partially successful.
Many of the ship's hard hats were in poor repair and did not fit
properly, therefore causing more problems and dangers than solving. It
was also obvious that some people would not wear them unless it was
official policy as it is on the RV Wecoma. Our official policy should
be clarified and if it is determined that hard hats will be worn I
suggest we purchase our own and assign them to specific personnel so
that they are available and fit properly.
At Kahe Point we conducted a 1000 m weight cast to pressure test one of
Mimi's transponders as well as other equipment. This was followed by a
PNF cast and the GOFS 1000 m cast. We departed Kahe approximately
1600 hrs and steamed to station ALOHA. We arrived at the trap
deployment site (approximately 3 miles east of center), approximately
2400 hrs and completed deployment by 0230 hrs. Deployment went
smoothly except for the loss of one trap at both 300 and 500 m due to
collar failure. RDF and strobe lite functioning was verified and we
proceeded to station center. The WOCE deep cast was conducted followed
by 39 hrs of 1000 m "burst" sampling. During this period we collected
all core WOCE and GOFS samples. We conducted an additional cast at the
end since we fell somewhat behind during the GOFS 0-200 m cast. This
cast took 2 hrs to sample (not counting salt sampling), with 4
experienced personnel conducting the sampling ! The only additional
samples we took were 12 depths for Quay and duplicate samples for
alkalinity. This is becoming a very labor intensive cast and therefore
it may be to our benefit to overlap the shifts in such a manner that we
have additional personnel available for this cast and the following
primary productivity cast in order to maintain the 3 hr CTD schedule.
The failure of the in situ RDF necessitated visual tracking of the in
situ array.The reason for the failure appears to be a bad connection.
We assembled the transmitter, verified output via red lite LED and
placed it in the spar buoy. Further signal verification from the
bridge indicated no transmission. The transmitter was removed from the
buoy and no red lite indicator was visible. The cap was manipulated to
produce a red lite output and the signal verified from the bridge. The
transmitter and strobe assembly was once again placed in the spar
buoy. The bridge continued to receive the signal until the buoy went
over the side.
During this cruise we tried to access Argos data directly from the
ship. We had made arrangements with Service Argos to dump the data
into the Alpha Helix mailbox in Miami and we anticipated accessing the
data via ATSVAX satellite. If this did not work then we would access
the data directly via Inmarsat and if we still had problems we had a
backup system at the University. We were successful in completing the
ATSVAX link to Miami but alas, there was no data from Service Argos.
We tried at several different time-points with the same result -- no
data! The direct approach via Inmarsat to Argos was successful and we
obtained satellite positions. From the information obtained it
appeared that the Traps were tracking almost due north at ~ 0.3 kts.
Following completion of the core sampling Ricardo made a cast for an
HPLC fractionating and concentration experiment followed by a series
of net tows. John Constantinou completed a cast for his mixotrophic
experiment and continued to process samples for Mike Landry's grazing
inhibition determination experiment.
While samples from the previous casts were being processed we slowly
steamed to the supposed position of the traps. Our last Argos fix was
1930 hrs on 9 Aug. '91. We decided not to interrogate Argos unless we
were unsuccessful in locating the traps via deadreckoning from the
established drift tract. As we steamed towards the predetermined
location we picked up the RDF signal and located the traps without
difficulty. The final CTD cast was a Tricodesmium collection by Ricardo
while standing off the traps. The final cast was a 2000 m weight cast
to pressure test Mimi's transponder #2. Trap recovery was initiated
~0200 on 12 Aug. '91 and completed ~0330 hrs without incident.
Departed station ALOHA and arrived at Snug Harbor1600 hrs 12 Aug. '91.
SAMPLES COLLECTED BY
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GOFS Core GOFS/WOCE
WOCE Core GOFS/WOCE
WOCE, GOFS salts WOCE
L. Campbell GOFS
P. Quay GOFS
M. LANDRY John
Constantinou
J. Constantinou's John
Constantinou
HPLC fractionating exp. R. Letelier
Trico net tows R. Letelier
Trico water bottle R. Letelier
L. Sautter GOFS
J. Christian J. Christian
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