High-density XBT cruise AX081111 report
Ship : Maersk
Vilnius
Call sign : 9V8503
Ship Rider : Fergus Mckay
Dates XBT’s deployed : November 05th to November 22nd
2011
a) XBTs
deployed : 362
b) Drifters
deployed: Eight drifters were
deployed.
ID DEPLOYED POSITION
1 37127 11/07/2011 – 18:22 220 00.00' S 0030 37.00' E
2 81908 11/08/2011 – 05:40 200 00.00' S 0010 15.10' E
3 37128 11/08/2011 – 16:33 180 00.00' S 0010 02.15' E
4 81914 11/09/2011 – 03:49 160 00.00' S 0030 18.05' W
5 37125 11/09/2011 – 14:00 140 01.77' S 0050 33.21' W
6 37126 11/10/2011 – 02:32 120 16.00' S 0070 49.80' W
7 81909 11/10/2011 – 14:10 100 00.00' S 0100 02.50' W
8 81907 11/11/2011 – 01:18 080 00.15' S 0120 13.90' W
c) Profiling
floats deployed: No floats were deployed .
ID DEPLOYED POSITION
d)
Equipment
tools and supplies needed: A spare MK12 card, a new A/L main cable, A new hand launcher, A spare
connector box and a new battery for the UPS.
e) Problems:
I had major problems with the equipment initially. The main A/L cable had a
faulty brown wire which caused faulty drops. Once the problem was diagnosed I
replaced the brown wire with the black wire and no further problems were
experienced. On trying to use the hand launcher as a backup I found that both
the black and the white wires showed no continuity on the multi-meter. So I cut
away most of the cable leaving only enough to reach the launching point. This
solved the black wire problem, but the white wire was broken in the handle of
the launcher, so I replaced it with the screen. It worked after that. While
trying to diagnose the problems above it also came to my attention that there
was no spare MK12 card, so fortunately the problem wasn’t with the card.
f) Recommendations: The Maersk Vilnius is a perfect ship for
deploying XBT’s so I recommend we use her as much as Maersk allows us to. The
box of spares be checked and replenished, and all the redundant spares be
removed.
g) Other
narrative: The Maersk Vilnius is an ideal ship for dropping XBT's drifters
and argo floats, with it maintaining a very steady speed, and the point of
release close to the water, hence very few faulty drops occurred during my
trip. The distance from the cabin to the launcher and antenna isn’t far, making
installation a lot simpler. The Captain, officers and crew were also very
hospitable making for a pleasant voyage.
h) Ship
contact: Captain Juanillo A.Tiu
email: 908VILNIUS@maersk.com
Summary of cruise AX081111 between Durban
and Newark
AX081111 was conducted aboard the Maersk Vilnius. I boarded
the ship at Cape Town on the morning of the 04th of November 2011 and
did the installation and testing of the equipment. The test drop was done when
leaving Cape town on the 05th November 2011. After leaving Cape Town
the drops for the AX081111 commenced on the 05th at 03H37. The ship
birthed at Newark during the morning of the 23rd November 2011.
In total 362 XBT’s were deployed. High density deployments
commenced from a depth of 200m once leaving Cape Town but due to equipment
problems I changed to Intermediate density from the 7th November .Unfortunately
there was a problem with the temperatures being approximately 10ºC out when
using the auto launcher. I tried using the hand launcher, but it also wasn’t
working. So after finding that the black and the white wires were broken I cut
away most of the cable and only used the length I needed. This solved the
problem with the black wire. I then used the screen instead of the white wire
.The hand launcher was tested and found to be working on the 08th
November 0800 and successful drops were obtained from then till the end of the
voyage. I still however carried on searching for the fault with the auto
launcher. After ruling out all other possibilities I found that the problem was
in fact with the auto launcher cable. The resistance on the brown wire was too
much, hence throwing the temperatures off. The brown wire was switched with one
of the extra earths ( the black wire) and the Auto launcher was tested and
found to be working fine. Therefore drops were commenced from the auto launcher
from the 09th November at 11h31. Intermediate density deployments
were done at a rate of one per 40km until 10°S. High density deployments at a rate of one per 30 km, were started
at 10°S until 15°N. Intermediate density deployments commenced again from 15°N
until a depth of 200m was reached before Newark.
Eight drifters were deployed as follows.
ID DEPLOYED POSITION
1 37127 11/07/2011 – 18:22 220
00.00' S 0030 37.00' E
2 81908 11/08/2011 – 05:40 200
00.00' S 0010 15.10' E
3 37128 11/08/2011 – 16:33 180
00.00' S 0010 02.15' E
4 81914 11/09/2011 – 03:49 160 00.00' S 0030 18.05' W
5 37125 11/09/2011 – 14:00 140 01.77' S 0050 33.21' W
6 37126 11/10/2011 – 02:32 120 16.00' S 0070 49.80' W
7 81909
11/10/2011 – 14:10 100 00.00' S 0100 02.50' W
8 81907 11/11/2011 – 01:18 080 00.15' S 0120 13.90' W
The weather was fine for most of the
cruise. Large swells were experienced on departure for
two days and also on the evening of the 19th and during
the day of the 20th .
Once the initial problems were ironed out only three second
drops were done. The first two were for the wire snapping on release and the
third was when the XBT was released but no splash was detected. One XBT was found
to be faulty before launching.
Overall, other than the first couple of days of fault
finding and repairing cables, the voyage went well. The Maersk Vilnius is an
ideal ship for XBT deployments since it maintains a very steady speed and the
point of release is close to the water resulting in very few faulty drops
during my trip. The distance from the cabin to the launcher and antenna isn’t
far making installation a lot simpler.
The Captain and crew were very hospitable during the crew
and eager to assist during the voyage.
F.Mckay
Port Meteorological Officer