objectives:
1) locate and release 14.5 kHz transponder
2) visit Salut and measure depths in flange pool needed for construction
of j-hook
3) run Mesotech survey of the Bastille complex
4) locate marker R at Bastille and sample
5) additional sampling as possible
Dive was launched in rough, but improving, weather on time. The basket
took a hit when passing through the sea surface, dislodging one of the
gas tight bottles and the manifold sampling arm. Both of these were
returned to proper positions by the swimmers, but there were a number
of problems later in the dive that may be related.
We launched north of the transponder target location (5591,5120) and
drove during descent to place ourselves approximately 200 meters due
north of the transponder. We dropped weights at about 2000 meters and
trimmed to neutral buoyancy then traveled south noting ranges to the
the transponder. When the range fell below 0.1 second (two-way, about
75 meters), we adjusted depth to the nominal depth of the transponder
and continue south toward it, sighting it soon thereafter. Its
location (5610,5141,2061) at a range of 0.172 seconds to the C (10.0
kHz) transponder. We traveled down the rope to the release, finding
that the transponder was being set by the currents to the south. Fix
at the release point(5617,5154). The transponder was released just before
1000L.
We then flew up to cross the axial valley at height, taking a course
toward Salut (4840,5870). We arrived somewhat south of the target, so
drove north adjusting depth to return to the seafloor by about 1050L.
We reached the seafloor somewhat west of Salut, which we located shortly
thereafter. Measurements were made of the depth of the main flange
pool: first to the right side recording 2 cm and less, then in the
more the central portion where the depth was 3 cm. The smaller pools
further back under the lip of the flange were quite shallow (<1 cm).
Finished here about 1135L.
We then hopped to the starting location of the Mesotech survey (target
(4850,5950), actual (4860,5965)) to check the seafloor depth which was
2195 meters. (At this point we observed a structure with one smoker on
its upper surface which we eventually returned to at the end of the
dive to sample.) This depth was consistent with the existing map so we
chose a flying depth for the survey of 2175 meters which would clear
all known topography by at least 6 meters. About 1155L, We began a
northbound line asking for x=4850, but it was evident that we were
closer to x=4860, so mid-line I requested he simply stay on that x
value. At the end of the line we made a right turn trying to come back
down x=4870, but despite gyro readings close to 180, we made a SSE
course, reaching x=4890 by the end of the line. We made a right turn,
heading toward x=4850, another right line onto this x value, which we
held well, two right turns to put us on x=4870 headed south, two left
turns to put us on x=4900 headed north, then two left turns to put us
on x=4880 headed south. In retrospect I missed running the x=4990 line
in either direction. The general quality of the lines seemed to
improve as we surveyed, however I cannot recall any specific change in
strategy that would indicate why. Depth control was not as good as
might be desired and more attention should be given to providing the
pilot feedback on depth. A major annoyance was not having navigation
information overlaid on the Mesotech display, requiring switching back
and forth between channels. Survey complete about 1250L.
Time for locating R and sampling. We were located south of the
Bastille complex at about x=4880 and began driving on a course 000. We
reached the gap between Puffer and Sully and both Christian and Blee
could see a marked on Sully, but could not read it. I could see Puffer
to port, provided that there is one of our 95 large markers at its base
(at a distance I could not read). But we were clearly south of R so
continue north, reaching a marker P shortly. No P on the map? We
considered two possibilities--there was an unmapped marker or R had
lost one of its legs. We inquired of the surface, by this time Blee
had become nervous seeing smoke and "got of there". We returned to the
seafloor in a patch of tube worms and near a time lapse camera. S&M?
No nav says not. Inquired of surface and found it was one of the
Canadian instruments located just north of Peanut. My impression was
that nav was not consistent with this either, but will need to go back
and look. Decided to take a southerly course and pass west of Peanut
then turn east. Successfully circled Peanut, but immediately
recognized what we had done, so this time past by Peanut on a southerly
heading then turned "left onto 270" then headed forward. Came up into
the area surrounded by Bastille-Needle-Tara-Sully-Puffer and I saw the
P marker well below us to port. Turned and came down to begin sampling
with the manifold, about 1330L(?).
Initially the manifold program couldn't see the tip temperature probe,
giving a reading of 999.9. While we were trying to figure out what to
do with that, the current to the intake pump increased to near limit.
Blee removed the probe then returned it to the orifice at which point
the tip temperature began working. Why? Temperature increased to 380.x
but current on the pumps continued to be problematic, especially the
flush pump which would not run more than a few seconds without tripping
a breaker. But with the main pump running full we could maintain a
reasonable (high 200s) temperature at the outlet, so it seemed sensible
to fire the bottles nonetheless. This was done in the sequence port
outboard major, port inboard major, port gas tight, starboard gas
tight. Marker AM was placed at the vent sampled. (n.b. informed Marv
of these problems when we surfaced).
Its now about 1405L. What do to next? We had power to do something,
but not necessarily sample. I was not confident of finding another
sampling site on Bastille easily and considered the structure we had
found just before the Mesotech survey as a reasonable target as Blee
had commented earlier that it would be easy to sample. We hopped to
its south and approached from there, finding it easily. We sat at its
southern edge for a short while. I could see a flange about 1 m x 2 m
which had detached from this structure and fallen intact landing on a
large pillow. It had been detached for sometime judging by the extent
of oxidation. Blee preferred to sample from a different angle and
circled 270 counterclockwise around it, putting his tail into the west
wall of the valley. Sampling set was (4853,5972,2196) at heading 087.
Alvin temperature probe gave 349 degrees. Sampled in sequence gas
tight blue 2, which Blee didn't think fired, gas tight red 5, which was
the perfect sample if it fired, major blue 10. The next major was
caught in the mesh and Blee lost his sampling set while wrestling with
it. He then wrestled with the markers which were "in a pile", in
retrospect probably knocked down during the launch by the fallen gas
tight sampler. After an excursion to Puffer (I saw marker U) we
returned to the west, finding it nearby and placed marker AP. We had
been out of power for nearly 30 minutes and dropped weights to surface
immediately.