CD 157: Investigating the submarine canyons offshore Portugal


Daily diary

Sunday 6th June 2004

Weather; Air temp 17.5oC, wind speed 2.5m/s, air pressure 100mB, [The weather station has been reconnected!]. Same dress code as yesterday.

Ian writes...

Main achievement

Today we are doing some of the school experiments. Students at Wyvern Technology College devised a test to determine the effects of increasing pressure with depth.  They have based their idea on an existing test which is to send down polystyrene cups to the bottom and then compare their size when brought back to the surface. They have made two modifications to this.

The first refinement is that we are sending down some expanded polystyrene slabs of roughly equivalent volume to different depths and then comparing how much each has been compressed. The second is to send some blocks of different volumes to the same depth to see if each is compressed by the same amount.

They have made predictions for all of their tests and I have asked the on board scientists what they predict. I have collected some interesting ideas.

What do you predict?

The findings will be in my daily diary tomorrow – just to keep you guessing!

Samples were put into a pillow case and tied to the megacorer which was lowered to 4800m

Samples in pillow cases prior to immersion – figures show amount of wire out [click to enlarge]

Polystyrene slab returns from the deep

The polystyrene slabs at the start of the experiment


Last night was curry night!

Today is dhobi day! "I’ve done my dhobis!" or "I’ve just done a good dhobi" are not nautical terms that I have been familiar with and, perhaps after curry night, you may be forgiven for thinking that a dhobi is usually brown and squidgy. Well, you’d be wrong and in fact very far from the truth, it is simply laundry day - you use dhobi dust in a dhobi engine. The word ‘dhobi’ is Indian and has something to do with washing.

The results from our polystyrene experiment have just come to the surface – they are excellent and surprising. Check it out tomorrow.


Teamwork is a wonderful thing and it is interesting to see how it grows and why it is so good. At the start of our voyage some people knew each other but not all. We initiated into the process of sediment sampling. Each core sample is very expensive - probably running into thousands of pounds and we were responsible for part of the process of gathering quality samples. After one week all of us have become familiar with the system and become competent at a number of tasks.

The process goes something like this: the technicians assemble and mount the corer prior to the ship’s crew winching it down to the sea bed. Meanwhile we log the exact position and time as well as assist, where we can, in the assembly process. The rate of veer [cable unwinding] is controlled by the winchman. From 100m above the sea bed it is lowered very carefully – a TV monitor displays the winch unwinding, the ‘cable out’ and the load on the cable. When the amount of load drops, the corer is in the seabed and the winch is gently reversed so that the corer is hauled back up. Once it breaks the surface the technicians go through a careful procedure of securing and lifting the sample back onto deck. Remember, this can weigh up to a ton and be 12m long.

Following that, we extract the plastic liner containing the sediment from the steel coring tube and cut it into 1.5m segments. It is then sealed, labelled and then taken to the wet lab. Here we cut each sample in half lengthways, store half and an expert describes the other half. Then follows more labelling and sealing and perhaps some photography. The two halves are taken to the cold store and here they will stay until the ship returns to the UK.

Observing the people in action I think that teamwork can be defined by the amount of trust that each of us has in the other to do a good job.

Elena writes...

I can’t believe I’ve been here ten days already! At first I though time past slowly, but now one day seems to merge with the next and they are passing faster than I’d like.

Tomorrow (Monday) UK students return to school after the half term holiday and I’m hoping they enjoy checking out the website. A personal message to my own students: you better spend your time reading all my diaries and sending me sensible questions - no games or I’ll email you a detention! And to the science club, we are sending the polystyrene shapes and cups down tomorrow so I’ll update you with the results.

The science club at Arnewood School designed an experiment to find out the effect of increased depth on pressure.  By sending polystyrene cubes and cups (that easily compress under pressure) to different depths and then comparing the initial and final size we will be able to find out. Check out Ian's report on the polystyrene experiment.

Here are some photos of the science club designing the experiment:

Arnewood School Science Club wrote messages on pieces of polystyrene to send down with the coring equipment. The message on the polystyrene reads: "The crew - if this shape doesn't come back nor will you so it better, from Lizzie" !

The pigeon we rescued is doing well. This evening another two pigeons arrived on the ship, probably his mates wondering where he is!! We also have a couple of swallows on board, hopefully tomorrow when we get closer to land they might be able to get back.

Again in the evening whilst coring the light was beautiful, it’s a pleasure to work in the changing environment.

Two swallows take a rest on the ship

Ruth, Elena and Sara enjoy some late evening sunshine

A few clouds make for spectacular sunsets

Veit takes a few moments rest to admire the sunset

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October 2003
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