May 22,
1998
Part B
Position as of 22 May, 19:30 local
27 deg 53min N
91deg 31min W
Conoco Production Platform, Green Canyon 52
|
An all too abrupt end
NR-1's 1998 Gulf tour came to an all-too abrupt end on
Friday when the submarine lost one of its bow thrusters. The part is vital
for safe submerged operation of the submarine and cannot be repaired at
sea. Although NR-1 is in no jeopardy, she will have to be towed back to
her Groton, CT home-port for repairs before she can dive again.
Sadly, all of the plans for science and survey in the Gulf
and at the USS Monitor wreck site will now have to be deferred to a future
cruise. The science party had to get off of CAROLYN CHOUEST to let the
NR-1 head home. Fortunately, a nearby Conoco oil production platform was
able to accommodate us until another ship is available to run us to shore.
The mood was decidedly bitter-sweet as we stood on the
platform upper deck and watched CAROLYN and NR-1 head off into the distance.
We were sad because things hadn't worked out nearly as well as we'd hoped
they would, but excited by what we had been able to accomplish and by the
prospects of trying again. Some of us (Ian MacDonald, Alice Pechahchy,
and Mike Peccini) will be back a month from now, diving with the smaller
submersible Johnson SEA LINK. Hopefully, it won't be too long until we
can have NR-1 back in the Gulf once more.
Thrusters are reversible propellers mounted in tubes.
NR-1's thrusters are arranged in an 'X' alignment both ends of the submarine.
The main engines move the submarine forward and backward. Propulsion from
the thrusters pushes submarine upward and downward in the water and allows
her to twist from side to side. There was never any danger from the failed
thruster. Captain Richard kept the submarine submerged at a safe depth
while the crew worked for several hours trying to make repairs after the
problem occurred. Once it was clear that the problem couldn't be fixed
from inside, he drove the submarine to the surface by going ahead on the
main engines and angling the dive planes to push us up. Near the surface,
compressed air was pumped into the ballast tanks so that NR-1 could float
with her deck and sail above the water. It was time for the disappointed
scientists to head back to CAROLYN.
Ironically, the scientists on NR-1 had just found a large
and diverse community of tube worms and other chemosynthetic animals when
the thruster failed. Here is Will Sager's narrative of the last hours of
GulfTour:
The end of GulfTour will be one of those moments forever
etched in my memory. We had submerged several hours earlier and descended
to site TAMU-17, a "dead-center" mound. The name comes from the
appearance on the sea surface side-scan sonar records, in which this elliptical
mound displayed a strong echo return with a spot in the middle from which
no sound at all returned, i.e., a "dead" spot. Ian and I hypothesized
that such dead spots were caused by brine pools. Because the brine has
a sharp interface, it reflects all of the sound energy away from the sonar,
like a tilted mirror, in contrast to the gassy sediments around it, which
scatter a lot of sound energy back.
We settled to within site of the ocean floor about 300
meters east of TAMU-17 and ran a track-line to the west across the target
point. At first we saw nothing but mud, although it looked a little abnormal
in that the usual burrowing by sea bottom creatures was mostly absent.
As we neared the target, we began seeing gorgonian sea fans in rows, all
lined up to face the prevailing currents. Gorgonians mean there is a hard
substrate to which they can attach. Soon, a few bivalve shells appeared
and then a some bacteria mats, both evidence of seepage were seen. And
then we sited the brine pool-confirmation of our working hypothesis! I
was elated. Ian was asleep, having been up all night-and I couldn't wait
to tell him. But it was to get better (and worse). West of the brine pool,
we sighted our first tube worm bush, a little one. OK, I thought, we've
got some chemos here too.
Then another tube worm bush drifted below the view-ports,
then another, and another dozens of big, lush tubeworm bushes. "Tube-worm
city!" someone said. A major new find.
That was just the first pass. We turned to run a leg back
in the other direction, 200 feet farther north. The idea was to make several
passes and get a round idea of the layout of the site and its features.
The second leg was equally interesting. Although fewer tubeworm bushes
were sighted, we crossed the brine pool again and it was larger here. We
also noted sediment flows coming from the north. Evidently the mud volcano
vent was nearby. This was especially interesting because on other very
active mud volcanoes we usually don't see such rich tubeworm communities-probably
because they don't like being buried by mud-flows. Were we looking at
tubeworm "Pompeii"? After the second pass, we decided on another
leg 200 feet farther north, to see if we could find the vent. On this leg,
we found the flows were coming from the south. We had the vent bracketed
now. But just as we turned to run a line in between our two previous lines-the
end came abruptly.
"We have a zero-k fault"said the XO (Executive
officer) from the conn. "We'll have to go up to 100 feet for a few
minutes to trace it down." Those were the fateful words that marked
the beginning of the end of GulfTour. What had happened was that a routine
check of electrical systems detected a grounded circuit (i.e., it's electrical
resistance is zero kilo-ohms). That's bad news on a submarine because an
electrical fire could be disastrous with limited oxygen and no place to
escape smoke and flames. Alice and I took break from our survey, figuring
it was a good time to grab a bite to eat. The activity increased and the
captain looked more concerned. Soon I noticed that all of the crew were
awake and checking systems. First some good news. The captain said the
short was in "non-vital equipment", meaning life-support and the
main sub workings were OK. But then the bad, I'm afraid its one of our
thruster motors. We can't repair it at sea and this must terminate the
mission." Neptune had decided that GulfTour was at an end. Disappointed
all, we began to surface.
It pays to be philosophical at moments like this. The
sea is a hostile environment and a major cruise without down-time owing
to equipment failures or loss is rare. We got some good data and discovered
some new chemo sites. There must be plenty more out there waiting for us.
I have new sea stories to tell. And I am filled with even more resolve
to do this again.
We'll be back. |
