31 March

Long-Term Ocean Climate Observations (LOCO) – D301/302

Cruise Diary – 31^st March 2006

Petra counting the paying out

of the mooring cable

Friday - Last day of the Dutch part of this cruise. Only 2 relatively short moorings had to be deployed on the Mozambique side of the channel. A big difference with the previous days was that the ocean now was again more like a real ocean, and not like a flat lake. Waves have set up due to the breeze that came up during night. Many of us did not sleep so well because we need to get used to rolling again. Despite this change, the deployment of these last moorings went smoothly.

Splash from the last weight

One of the tasks during the deployment is ‘counting how much wire has paid out’. On the picture Petra does this by counting the number of turns that the winch makes. This needs to be done to be sure that our instruments are located at the right position. Marcel made a spectacle of the last action of this part of the cruise by releasing the weight from a few meters above the sea surface. The splash reached the deck and some of us. At 11.00 am the Discovery set course towards the south where the English part of the cruise will take place.

However, in the afternoon there was a lot of excitement. We got a phone call from our home institute at Texel where a message had come that one of our transponder drifted somewhere in our neighborhood.

Each transponder also sends its unique identity. Thus we checked immediately to which mooring this transponder belonged. It did not belong to one of the moorings that had just been deployed, but, to the ‘lost mooring’ as some of us (including myself) saw on a list. Thus, the conclusion was that this lost mooring had come to the surface and drifted somewhere between the position of the ship and the place where we left the mooring section. Immediately the Discovery changed course and headed northwards, to arrive at some 18.00 pm at the location of the last known position of the mooring. Meanwhile everything was prepared to be able to recover the mooring again. Then, more or less by accident, we took one of the 3 spare transponders out of a container, as we wanted to test whether we could receive the signal with the ship’s instrumentation. To our surprise, this transponder appeared to have the same identification number. A further surprise was that the magnet that is taped to the instrument at a specific location to stop it sending, had shifted such that the instrument was sending. Thus the conclusion was that this transponder, that had been on the ship all time, had started to sent it’s position. Checking the number with other lists like the cruise report from the previous cruise, confirmed this: this transponder had not been located on the lost mooring, but was a recovered one from one of the others……

A bit shameful I went to the bridge and told the story. Happily they could laugh about it, also because this affair took all in all only some 5-6 hours. Thus at around 19.00 pm the Discovery sailed southwards again and we had a lot to discuss during the evening…