Happy Christmas …..

….. at home or aboard.

This week has been quite a mixed bag: an emergency medical, instrument recoveries, and (before they even get a chance to dry off), instrument deployments.

We reached Caldera in the evening of the 20th to meet a Coastguard vessel for the boat transfer for the medical evac.

And once the patient was transferred off we went back to the work area, with the lights of Caldera slowly disappearing over the horizon.

Transits are always a good time to complete the mandatory training for either lifeboats or, in this case, fire fighting.

Each member of the team had to demonstrate that they were able to handle a fire hose, although the scientific and technical parties are always just a back up to the ship’s crew.

First the operations lead ……

Then our electronics specialist ……

And finally our newest recruit, our software specialist.

The trick is to not get knocked off your feet!

Following that the real fun started with the first of our instruments to be recovered.

The trick with recovery is to first wake up the instruments acoustic system while it is on the seafloor.

Then, once awake, send it the “burn” signal to instruct it to connect its battery across the burnwire so that it starts to corrode as the sea water completes the circuit.

And then we hold our breath for seven minutes – the burn time – and wait to see if it leaves the seabed.

We have a nifty bit of software to help us monitor this process, whose output we can send to our IT system to display it on screen as shown below.

The green stripe is the “burn” command being sent and the red speckles each are a “ping” sent from our transducer on the ship to which the acoustic unit on the instrument should respond with its own ping shown by the blue dot.

And if the instrument is ascending from the seabed, the blue dots should move nearer the top of the screen, which represents sea level, over time.

And as the speed of sound in water is well known at 1500 m/s, and as we can measure the depth to the seabed using an echo sounder onboard, we can predict the rise rate from the gradient of the line of blue dots and, thus, when the instrument will surface.

Its always a good idea to predict that so that we can let the ship’s crew know so they can plan hand-overs, tea breaks and other essential activities!

Eventually the instrument appears at the surface and the tracking system also gives us a good idea how far away from the vessel it will be.

Hard to spot at night – but you soon get your eye in.

Easier to spot in the bright spot lights when finally along side – a surfing recovery for this one.

And then out of the water onto the deck to have a thorough wash down with fresh water before removing the datalogger tube for the all important data download.

Sometimes they come in so fast they float past the porthole window without being spotted apart from the recovery team and the bridge officers!

When they finally land on deck they are dropped straight onto their new anchor for their next deployment.

So, while one team member deals with the data from the recovery, another resets the instrument ready for its next deployment.

Fast and efficient, and queued up ready to be redeployed. The flag is the signal to the ship’s crew that it is ready and the next to go.

No flag, no deployment!

All instruments were recovered and the next set deployed by the evening of Christmas Eve, and now they will be shot into for several days to come, which means …..

…. an undisturbed Christmas lunch for us, while we plough through quality checking the recorded data!

Itr might be 30+ degrees and sunny in the Pacific but you can’t beat a turkey dinner for Christmas.

Back at home the Boss has been out an about on a Boxing Day walk, and doing a bit of Ordnance Survey trig spotting.

This one is on top of a pill box near the old Severn Crossing bridge. The top needed a bit of a spring clean to see it.

And the Boss also reports the first snow drop sighting – has spring already arrived?

Happy Christmas everyone.

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