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