Week Seven

At Sea Report from the Bismarck Sea: The final week at sea
December 31st, 2000

The final week at sea was full of action as we started with Christmas and a lengthy logging job on December 25th. We had a Christmas party on the 25th starting at noon. I was only able to catch bits and pieces of the festivities because were getting ready for work once again. The show had several concerts and singing by the crew and a few of the scientists. It sounded really good because most of the people participating had been practicing for several weeks prior to the big performance. The hard work paid off. The grand finale with the Filipino all star band especially impressed everyone . We all received a present from the gift exchange program. Most of us bought an inexpensive gifts while we were in Guam to contribute to the exchange. I got a souvenir guitar that says I love Guam.

After catching a little bit of the Christmas show it was back to logging as we had moved to the active hydrothermal area (Roman Ruins) and drilled Hole 1189B. This hole was drilled to a depth 206 mbsf. We deployed our first logging string and it was kind off tight in a few spots, but we reached a depth of 198 mbsf or 8 m above the drilling TD. In the second deployment things got a little bit worse as we could not get deeper than 132 mbsf. It seems that the hole conditions had deteriorated and the borehole walls had collapsed. We finished our logging job with two more deployments to this depth and we were done.

After finishing logging Hole 1189B we moved close to a vent and decided to start a hole using the logging-while-drilling (LWD) resistivity at the bit (RAB) tool that I mentioned in my fourth report. We had measured the temperatures in Hole 1189B and they had not exceeded 68º C. These temperatures reassured us that we could drill a hole in this environment and keep the temperature low enough to minimize the risk of tool damage. Nevertheless, it was an agonizing 24 hour period that we waited until finding out that the tool was OK and that we had good data. The TD for Hole 1189C was 166 mbsf.

Did I say that we move around a lot? Well, we went back to Hole 1188F to do a temperature measurement. If you remember, Hole 1188F had shown an increase in temperature of 35º C in 24 hours. We deployed a memory tool down the hole and when we downloaded the data we were in for a big surprise. The temperature had risen to slightly higher than 300º C in 7 days! That was a pretty amazing change of temperature of over 200º C since our first measurement. We made another temperature log to confirm our findings and then we collected a water sample. It looks like the bottom of the hole has an extremely steep thermal gradient while the top of the hole is very cold.

All these operations took approximately 5 days. These were 5 days in which we all had very little sleep and we had to manage by talking quick naps whenever we could. On December 30th we were told that we were going to have to go to port to let one of the crew member off for personal reasons. We finished up our work and headed off to Rabaul in New Britain. More on this in my next report.

One note of importance that had nothing to do with science was that during the course of the cruise, we have experienced several storms with some high winds. These storms had managed to blow a couple of land birds on board the ship. Both were the same type of bird that had iridescent and long plumage. One of them was taken back to land on one of the frequent helicopter rides and was successfully set free. Unfortunately the other one was injured and did not survive.

Well, until the next week when the cruise comes to an end in the year 2001.

Gerry