May 28

5/28/00

Our last day working in Antarctica began with a brilliant sunrise, clear skies and a comfortable 17 degrees F. Two coring operations this morning ended our science work on the ship and now packing is well underway. All the equipments we have had out for the past couple of weeks need to be packed away and secured for the up coming crossing of the Drake Passage. The sea ice has damped all wave activity for the past two weeks so the motions induced by the open ocean will be something we have not experienced for a while. (sea sickness pills anyone?)

The jumbo piston core operation went well into the early hours of this morning. The cold night froze the liners in the core pipe and we ended up disassembling the entire corer so we could take each 10 foot 350 pound section of pipe into the lab, thaw it and remove the core liner. This proved successful and we recovered 22 meters of core from the site. Because we had to disassemble the entire unit, the decision was made not to attempt another jumbo piston core this morning but we did do two simpler coring operations.

The jumbo piston core is never seen completely out of the water so I've prepared this illustration to show how it is set up and two photos of it in use.

A release unit is attached to the main winch cable and holds the jumbo piston core (JPC). The release unit is kept locked by the 500 lb weight of the trigger core. The entire unit is lowered to the bottom by the ship's winch. When the trigger core touches the bottom, its weight is released from the cable holding the arm on the release unit; the release unit opens allowing the JPC to fall free towards the ocean floor, taking up the free cable coiled at the top of the corer. If the slack cable is used up as the JPC impacts the sea floor, and the corer slides into the sediment as the internal piston draws up the tube, helping to overcome the friction of the sediment against the inside walls of the corer.

When all works correctly, the corer penetrates deeply into the seafloor recovering a long continuous core of sediment.

Both shifts of marine techs work to bring 80 feet of jumbo piston core on board following a successful deployment in the soft sediments of the northern Prince Gustav Channel.

Marine Tech Mike Lewis makes a final check of the jumbo piston core as it is lifted from the cradle on the side of the ship. The release mechanism and coiled free fall wire with the attached trigger core are clearly visible.

"An additional image of migrating Adelie penguins.
Enjoy, we sure did."

"As we headed north late this afternoon the captain brought the ship to a halt and called everyone to the bow. Migrating Adelie penguins blocked our path. What a great way to leave the ice!"

Cheers,

Dave




		May 28, 2000 End of Science Photos of marine techs Penguins 5/28/00 Our last day working in Antarctica began with a brilliant sunrise, clear skies and a comfortable 17 degrees F. Two coring operations this morning ended our science work on the ship and now packing is well underway. All the equipments we have had out for the past couple of weeks need to be packed away and secured for the up coming crossing of the Drake Passage. The sea ice has damped all wave activity for the past two weeks so the motions induced by the open ocean will be something we have not experienced for a while. (sea sickness pills anyone?) The jumbo piston core operation went well into the early hours of this morning. The cold night froze the liners in the core pipe and we ended up disassembling the entire corer so we could take each 10 foot 350 pound section of pipe into the lab, thaw it and remove the core liner. This proved successful and we recovered 22 meters of core from the site. Because we had to disassemble the entire unit, the decision was made not to attempt another jumbo piston core this morning but we did do two simpler coring operations. The jumbo piston core is never seen completely out of the water so I've prepared this illustration to show how it is set up and two photos of it in use. A release unit is attached to the main winch cable and holds the jumbo piston core (JPC). The release unit is kept locked by the 500 lb weight of the trigger core. The entire unit is lowered to the bottom by the ship's winch. When the trigger core touches the bottom, its weight is released from the cable holding the arm on the release unit; the release unit opens allowing the JPC to fall free towards the ocean floor, taking up the free cable coiled at the top of the corer. If the slack cable is used up as the JPC impacts the sea floor, and the corer slides into the sediment as the internal piston draws up the tube, helping to overcome the friction of the sediment against the inside walls of the corer. When all works correctly, the corer penetrates deeply into the seafloor recovering a long continuous core of sediment. Both shifts of marine techs work to bring 80 feet of jumbo piston core on board following a successful deployment in the soft sediments of the northern Prince Gustav Channel. Marine Tech Mike Lewis makes a final check of the jumbo piston core as it is lifted from the cradle on the side of the ship. The release mechanism and coiled free fall wire with the attached trigger core are clearly visible. "An additional image of migrating Adelie penguins. Enjoy, we sure did." "As we headed north late this afternoon the captain brought the ship to a halt and called everyone to the bow. Migrating Adelie penguins blocked our path. What a great way to leave the ice!" Cheers, Dave tewksbda@nbp.polar.or g <<May 27 pm * May 29 am >>

End of Science