Wednesday, 26 June 2013

Cutting the dive hole

Others heading out for sea ice training.

In order to go diving, one needs a hole in the ice in the first place. No, unfortunately, they are not the comedy round ones – not really practical enough I guess. The chainsaw which is used to cut the hole needs warming up at base first and then gets wrapped up to stay as warm as possible. Once on the ice, the rectangle is marked and the outline cut into the ice with the chainsaw. The rectangle is cut out

Steam coming out of the tide cracks.

with divisions of 6-8 blocks. Each block gets an ice screw so that two people can get the block out. We always cut 2 holes so that we have got a back up hole in case one of them is used by seals as breathing holes. While the holes are not being used, they are covered with bit boards and marked with 4 flags. Hopefully, I can use the chainsaw myself the next time we need to cut holes. However, for now the holes are there and we just need the good weather to go diving through them! (no need to mention the excitement ...)

Amber taking the ice cores and others
watching world class science being done.

Amber (Dutch Marine Assistant but actually Canadian) came out with us to take some sample ice cores in preparation for taking proper ones in the other bay with a CTD. When the cores are being melted, salty water needs to be added so that the solution ends up being the right salinity for salt water to avoid any of the organisms dying too early (they would break up and spill a lot of the things which are measured into the water and hence mess up any data). At the same time Amber looked at how long it would take for the cores to melt. They cannot be warmed up too quickly (fridge at +4 degrees is ideal) as this again would kill all the organisms trapped in the ice. At the same time if the cores are left too long, too many variables (ie gases in the water) would change and organisms would be active and hence influence measurements as well. 

Tommo telling Pete how to cut the hole.
Marking out where to cut.
Proper cutting action!

Dive hole is ready!
Putting ice screws in so the blocks can be
lifted out later.
And now getting the blocks out (since than
we have lifted out much bigger ones ...)

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