20 Oct - Science begins
RRS James Clark Ross Diary
Noon Position: 53.54.1 Deg S, 37.24.1 Deg W
Distance Travelled since Grimsby: 9359.0 Nautical Miles
Days since leaving Grimsby: 40
Air temperature @ Noon today: 0.3°C
Sea temperature @ Noon today : 0.9°C
Weather: Moderate/poor, WxN, Force 7
Start of Science
Except for brief visits to King Edward Point and Bird Island the James Clark Ross has been busy with science all week. We were all thankful for a relatively calm week of weather which gave the opportunity to crack on with a week of science to the North of South Georgia without being thrown around too much. We completed the Western Core box and deployed a couple of "Water Column Monitoring" buoys during the week and finished ahead of time. Compared to last year we had a relatively easy ride and are three weeks ahead of where we were at this time last year. This is primarily because of an early start to the season due to the extra work at Rothera.
We had the chance to nip into Bird Island on a suitable afternoon during the week to pick up 4 people from base and drop 3 more off. Jon, Chris and Jaume were set ashore, ending a frustrating time for them when they had been involved in the relief of Bird Island last week only to be whisked off on the JCR while their beds on base were occupied by maintenance personnel. They finally got in to the base and Chris can now pick a bunk that will be his for 2½ years. The exchange was made a little bit spicy when we found the bay was full of sea ice and bergy bits.
However, we found a safe area of rock to land the 3 humbers and dropped off the guys. All the time we were watched by a leopard sea who happened to be lounging on a berg nearby. We were glad that all the ice wasn't there last week during the main relief!
The Science Bit
Here we are about 20 miles North of South Georgia getting stuck into some science, more specifically science cruises JR79 and JR83. I've got the gist of what we are trying to do so I'll treat you to a whirlwind tour of the cutting edge (literally) of krill research!!!
JR79.....(aka 'The Krill Acoustic Survey')
Krill provides food for a high proportion of Antarctic wildlife, directly or indirectly. The poor little shrimp-like creatures are eaten by most animals (seals, whales, birds, fish, squid, penguins) and form THE KEY LINK in the food web. They live in the surface 200 m of water in the sea.
South Georgia is a crucial piece of land that many creatures use to breed on (seals, birds, penguins) or live near in the shallow seas (fish and squid).
The amount of krill in the sea (the biomass) has a direct effect on the ability of other animals to live and reproduce.
Why should we try and understand the factors affecting krill?
Firstly, since it is the major food source it effects all the nice fluffy animals we see on postcards e.g. seals, whales, birds, fish, squid, penguins. Secondly, it will help to understand the balance between fishing of krill and fish around South Georgia and will help to allow development of sustainable fishing quotas.
What factors control the biomass of krill???
The JCR has a series of transducers underneath the hull (these are the machines that go 'ping' in U-boat movies) that emit sound waves at different frequencies (38, 120 and 200 kHz). The reflected sound-wave from the water can tell us the amount of copepods (very small animals), krill (medium sized) and fish (bigger) and would pick up any stray submarines! The 'pinger' looks at the surface 300 m of water in a cone shape and gives a huge amount of data. This year is the first year where this 3D cone shape has been used and this new development gives a higher accuracy of information. It runs continuously as we sail at 10 knots along a precise course in the shape of a grid (aka search box) that is known as the WESTERN CORE BOX.
It is very important that the JCR has run the SAME EXPERIMENT in the SAME PLACE for the last 5 YEARS by REPEATING THE WESTERN CORE BOX exactly. This gives an idea of what is happening over time. Clearly when we sail over an area of water and take readings, we are only looking at a snap shot of time at the second of that hour of that day of that year. The problem is that snap-shot may not represent what is happening for the rest of the year (e.g. taking a picture of your garden on every Christmas Day is not representative of what it looks like in the summer no matter how many pictures you take!) The Western core box is normally surveyed two or three times a year (a photo of your garden on Christmas Day and Midsummer Day is better, but still does not represent spring and autumn). The data collected will be then analysed at BAS headquarters in Cambridge and any trends identified. Obviously the longer the experiment carries on, the clearer picture we will have as to the biomass in the sea. This can then be correlated with other factors that may have an effect - e.g. water temperature that are collected separately.
To solve the 'snap-shot of time' problem outlined above another experiment has been designed................
JR83.....(aka Moorings to investigate intra-annual variability in krill abundance and water-mass physical characteristics of South Georgia!)
Krill are the food of virtually every animal in the Antarctic.
The krill acoustic survey (above) provides a snap-shot measurement each year of the biomass of krill at one second of one day.
What is happening to the krill biomass for the rest of the year??
Difficult to say exactly.........read on.....
To get an accurate idea of biomass over the whole year we could leave the JCR sailing up and down along the lines of the Western Core Box ALL YEAR!
Hmmmm......expensive, very boring for the crew and the Antarctic bases wouldn't get any food!! Hey.....why don't we leave something there that can monitor krill continuously while we go away and do other things ? We will then pick it up at a later date. Simple.
To this effect two specialist buoys have been constructed to be dropped at a specific point to record what is happening to several different parameters in the sea water around it. OK. They have been deposited at two sites that are on the survey lines of the Western Core Box. This is important because we can compare data at that point with results from the JR83 experiment and allow us to make sure both are saying the same thing!
Each buoy has several clever monitoring systems on-board....
1 - Water Column Profiler - fancy name for 'the machine that goes ping'. It estimates the biomass of krill using sound waves
2 - Acoustic Doppler Current Profiler - fancy name for another 'machine that goes ping'. This one measures speed and direction of the water current at different levels of the water column.
3 - Conductivity/Temperature/Depth (CTD) - this one does what it says on the tin i.e. measures conductivity of the water (equals saltiness), temperature and depth of the buoy in the water. Those of you who are still awake will have spotted the deliberate mistake in the last sentence. Yep, the buoy is NOT ON THE SURFACE!
As I'm sure you are aware there any plenty of icebergs around here and they would make short work of a little buoy. 100,000 tons of ice versus buoy equals broken buoy. So, to get round this problem, the buoy is 200 m below the surface and it's instruments LOOK UP at the water above. Only the biggest icebergs are that deep and hopefully will not cause too much damage at that depth. The buoy is kept down at 200 m by a cable attached to 1 ton of old railway wheels sitting on the bottom of the ocean!
See a diagram of the bouy
The buoy is deployed from the stern of the ship and can be seen below left ready to go. Once the buoy has been streamed out in the water astern of the ship and the railway wheels are hanging-off over the stern, Doug can dramatically cut the rope with a handy fire axe to send the whole lot down to the bottom. The photos shows the orange buoy in the distance with small yellow bouys closer to the ship. Fortunately he didn't miss and ruin the deck!
Now, the really awake readers will be wondering how we get the data back from the buoy if it is permanently down that deep. When we come back to get the buoy in January we simply sail over the exact position, ping a "special ping" down at the buoy and hope the 'acoustic release' uncouples the cable and lets the buoy float up to the surface. This is a tricky moment as we then have to find the buoy and since it has 1000 m of cable attached to it currents may take it away from the ship. So, to make it more visible the buoy is painted tango orange, has a flashing light on top, a satellite beacon, a VHF transceiver but most importantly it has the BAS telephone number on the side, just in case!!!
The main threat to the buoys are from illegal long-line fishermen who may catch it on their line (legal fishing boats are warned it is there). Whales can swim down to have a look but shouldn't be affected by it. Large icebergs may still cause problems.
These two buoys are unique in the world in looking at so many parameters and are the first in the South Georgia area. They will be recovered every 6 months and the data down-loaded before re-deployment. One is positioned in deep water and one shallow but ideally there will be more located in the area over the near future. The main problem with the system is that it is only looking at two small areas in a vast ocean (like taking a photo of two plants in the garden every second for a year, doesn't tell you what the grass and trees are doing!) The two experiments will complement each other and give new insights into the exciting life of krill.
Well, that's what we have been doing most of the week!
What makes an icebreaker??
We are now sailing in seas containing many icebergs and may be soon be breaking ice near Signy. RRS James Clark Ross is designed to operate in extreme cold temperatures, sail in polar ice conditions and 'break' sea ice. This requires special features in the construction of the ship. I'll try and give a brief run down on the areas of the ship that give it the STRENGTH and POWER that make it suitable for extreme cold operation.
NB: The JCR is not classed as an icebreaker. We are classified by Lloyds as a CLASS 100 A1 ICE-STRENGTHENED ship. The reasons for this later.
Primarily we have a strong and stiffened hull to withstand contact with ice. There are several areas of the hull that have special strength. The bow's leading edge has a 150 mm thick metal stem bar to help protect it and this is surrounded by steel plate 26 mm thick. This is much thicker than a 'normal' ship and is made from extremely high quality low temperature steel. So called "Raex Polar" steel has enhanced properties at low temperatures and so has higher impact resistance. The metal plate thins to 21.5 mm along the sides and underneath the ship in areas of maximum ice impact, but this is still thicker than 'normal'.
Ice floating on the surface is likely to squeeze the ship from either side around the water level when we are ice breaking. When in ice, wind and currents can push large amounts of ice against the ship resulting in huge pressures. To protect against this, the ship possesses an ICE BELT, which is a thickened area of the hull that runs from approximately 1 m above to 1 m below the waterline and completely encircles the ship. Supported and stiffened by frames, the ice belt prevents this squeezing by ice flow from causing damage.
Inside the ship we have frames to maintain strength (like ribs in your chest). The JCR has ½ space frames (every 300 mm) at the bow and aft. This is double the number on a 'normal' ship. There is also a strong 'Box Keel' to ensure high stiffness in the hull. Another important point is that the hull has a very 'clean' shape with no bilge keels or stabilizers jutting out of the side or bottom of the ship. These would be damaged or ripped off by the ice.
One can see that the ship has a strong and rigid hull that can withstand the extra stress caused by ice work. Generally, the 'scantlings' (measurements of the ship) are all increased to provide the extra strength.
To drive the hull through ice requires huge amounts of energy. Power is provided by our 4 diesel generators powering two electric propulsion motors on one propeller shaft. At full power we generate 6 MegaWatts (approx 8,000 shaft horse power). This is similar to the energy needs of a town of 2000 homes e.g. Stanley. The single propeller drives the ship forward through the ice. The greater the forward power, the easier it is for the bow to rise up onto and crack and break the ice. The engines are electric and this has an important advantage for the propeller. Electric engines can develop torque (rotational force) even when the prop is not rotating. Effectively this means that if the propeller is stuck in ice and can't move then it can slowly turn and cut it's way free. Diesel engines cannot achieve this.
Engines produce heat and it has been estimated that they would overheat in around 3 minutes if it wasn't for a cooling system. This system sucks in cold sea water to absorb excess heat even when that water is full of lumps of ice. On RRS James Clark Ross, this is effected by a special design of suction chest, imaginatively called "The Ice Suction Chest" which includes a weir arrangement with grids, to keep the large lumps of ice out of the sea water strainers. It also incorporates a recirculation system, to spray water, which has already picked up heat from the engines, BACK into the suction chest, and melt any ice chunks which may have become trapped there. Using this crafty arrangement allows the JCR to maintain vital cooling while breaking through the densest ice the vessel is capable of dealing with.
The JCR operates in extreme low temperature that can freeze water and fuel that is stored in tanks next to the hull. To prevent this a 'thermal fluid' system pumps hot oil though coiled pipes in the tanks to maintain temperature and prevent freezing of important tanks. The thermal fluid also warms the rest of the ship and provides heating for showers, living accommodation etc. Effectively it is like a huge central heating system for the ship.
The fuel we use has special additives to prevent 'waxing' and low temperatures. 'Waxing' occurs when the fuel become thicker and sludges at lower temperatures and blocks filters in the generators.
We've even got heated windows in the bridge to stop them freezing up!
The JCR is designed to cruise at 2 knots through first year ice 1m thick. As I said before we are not a true 'ice breaker' and are classified as ice strengthened. Ice breakers have more powerful engines (up to 10 times more) and are normally bigger heavier ships that are primarily designed to open paths through the ice in the Arctic for commercial shipping. The JCR is a highly specialized ship and ice breaking is just one of it's many facets. Stay tuned for info on the other amazing features in the weeks to come..........
Currently we are seeing plenty of icebergs but are happy to steer round them at the moment. Next week on the way to Signy we may well encounter our first significant sea ice of the season.
King Edward Point again
On Sunday morning we popped into KEP to pick up John Dudeney who is travelling with the JCR at the moment. John is the Deputy Director of BAS and had spent the week checking out the new base at KEP. He will now continue with us to Signy. The brief visit gave Jeremy Robst a quick chance to iron out some computer glitches on base as we looked at the view and spectacular scenery. It was another beautiful day at KEP but we didn't berth and had left within an hour of arriving.
Sunday evening. We are currently cruising down to Signy and are passing a 'monster berg'. A huge ice berg measuring 43 miles by 18 miles is situated 3 miles to the starboard side. We can see an ice cliff stretching from one horizon to the other (this is what it must be like arriving at Halley - Ed). We are very happy in the lee of the ice berg as it give us calmer water to sail through! It can been seen on the satellite photograph on the left as the large white dumb bell shape mass to the left of the JCR position. Our route to Signy can be seen on the photo on the right. Sea ice can be clearly seen at the bottom of the picture and several more 'monster bergs'.
Coming up next week: Relief of Signy and horse racing!