Last updated: Tuesday 5th December 2017
Sadly things are not going very well for the RRS James Clark Ross, attempting to reach Rothera Station on Adelaide Island. The problem that we have is a band of pack-ice, which is 10/10th coverage, between us and the open water that we are trying to make for to then reach Rothera. Ice comes in many variations and until the ship is in amongst ice it is difficult to tell from satellite imagery just what it will be like. It might only be forty miles or so, but if the ice does not want us to progress there is little that we can do.
This is the view looking ahead this afternoon shortly after the ship was stopped by the ice. You can clearly see how far the ship managed to get and when I took the picture the ship was reversing up to then try to proceed forward again. Sometimes this is successful but others it is not, in which case the ship will then change course to see if taking a slightly different route will be any easier. Often it is not.
The ice that we are trying to work through is best described as porridge. It does not move out of the way easily, compacts ahead of us as we try to progress and fills in very quickly behind. Whilst we are always looking for the best way forward to our destination, it is important to know a way out just in case we get stopped. The ship does not get stuck as it will eventually move, so it is referred to as stopped.
This picture, taken over ten years ago, shows the James Clark Ross in a similar situation of trying to reach Rothera. The ice was very different then with 9/10th to 10/10th pack that was mainly big and vast floes (see the definitions at the end of this update). Look closely and you will see the ship in the middle of the picture along with the route that we had taken to arrive in this position. With the ship being 100m in length it gives an idea of what the ice was like for us. This is very different to what we are experiencing now and I have used to show that ice does come in many different ways.......all of which may stop a vessel.
A closer look at the ice and perhaps a better view to give the description of porridge to it. It really is horrible stuff! On the plus side, we are not rolling any more!
This is the view looking over the bow this afternoon as the JCR was trying to make progress through the ice. If you look at the Noon Position Report you will see that in the twenty-four hour period it covers the ship only manage 140 miles. Some of this will have been at two or three knots, other periods a bit faster but certainly well below our normal cruising speed. For those doing the driving a lot of concentration is required and constant adjustments to the power being used and the course being steered.
Looking aft one can clearly see where we have been but the track is already filling with ice again.
A closer look at the ice, with a lot of variations in composition. If only it were nice solid chunks that would break nicely and move out of the way!
Whilst not being able to enjoy Blue Planet II at the moment I am aware of some of the issues being raised and the big worry now is plastics in the oceans. Whilst there is growing concerns over micro-plastics, larger items can be found and as we were working through the pack this afternoon this buoy was spotted. Whilst it is large enough not affect such things as birds, it will have a line attached that will break up and could well enter the food system. The buoy will take years to degrade.
There are many mentions in my updates on the subject of ice, so I thought it might be time to try and clarify just what some of the terms mean.
Sea Ice: Sea ice is ice formed by the freezing of sea water. As the freezing process continues sea ice grows in thickness, gradually loses its salt and by doing so becomes harder with age. It is usually classified by its age or stage of development. Whilst fresh water freezes at 0°C, salt water with a salinity of 35 parts per thousand or corresponding specific gravity of 1.025 freezes at -1.9°C.
The stages of development of sea ice are as follows:
1. New ice. A general term for recently formed ice which can be in the form of frazil ice, grease ice, slush, shuga, ice rind, nilas and pancake ice. Thickness to 10cm.
2. Young ice. Sea ice in transition between new ice and first year ice and typically 10 to 30cm thickness.
3. First year ice. Sea ice of not more than one year's growth developing from young ice and 30cm to 2m thickness. Thin first year ice is 30 - 70cm, medium first year ice is 70 - 120cm and thick first year ice is over 120cm.
4. Old ice. Sea ice which has survied at least on summer's melt. It can be up to 3m or more thick. Second year ice is ice that has survived the first summer, 2m or more thick. Multi-year ice is ice is ice which has survived at least two summers and is 3m or more thick.
Pack Ice: The term pack ice refers generally to any accumulation of sea ice other than fast ice and this is classified in tenths as follows:
0 to 1/10 Open water
1/10 to 3/10 Very open pack
4/10 to 6/10 Open pack
7/10 to 9/10 Close pack
9/10 to10/10 Very close pack, which can be consolidated with floes frozen together, or compact with no water visible.
Floe: A floe is a relatively flat piece of floating ice usually described as 20m or more across and can be classified to size as described below:-
Small floes - 20 to 100m across
Medium floes - 100 to 500m across
Big floes - 500m to 2km across
Vast floes - 2 to 10km across
Giant floes - over 10km across
Noon Position Report Tuesday 5th December 2017
|Latitude:||67° 33.24 S|
|Longitude:||070° 24.76 W|
|Bearing:||270 °T, 53 Nm from Rothera|
|Total Distance Travelled:||1674.9|
|Total Steam Time:||168.8|
|Total Average Speed:||9.9|
|Wind:||Direction NE, Force 4|
|Air Temp: -0.1 °C||Sea Temp: -0.6 °C|
|Pressure: 971.2||Tendency (3hrs): Rising|
Previous updates from the current trip.
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