Wednesday, 29 January 2014

Sun on the water (Andrew Cormack)

April Fools Day 1989 maybe wasn’t the best day for one brand new RVS employee and three brand new Sun workstations to join RRS Discovery  in Barry. We all worked well in lab conditions but typical Biscay weather soon revealed some design flaws. So my first week of shipboard computing involved re-writing low level file handling subroutines in forty minute bursts between visits to the heads. I was eventually cured by being sent up the ladder to refill the wet-bulb thermometer. Discovering that I felt better standing on the ship’s roof than down in the computer lab taught me the cures for sea-sickness: fresh air, horizon and, if those aren’t available, bunk.

A later trip to the same 20ºW line gave me a closer look at the ocean, thanks to a boat transfer through a school of pilot whales from Discovery  to RRS Charles Darwin  to help re-build their computer systems after a power failure. Discovery  may not look big from the dock-side, but she looks enormous when you’re looking up a rope ladder from sea level.

My last Discovery  trip (post-rebuild) also involved intensive programming, when a team from Columbia University decided they’d like ground-referenced velocities from our ship-mounted ADCP. Unfortunately the ‘ground’ in the South Atlantic was 3000m away, far out of the ADCP’s range. Using GPS data to subtract the ship’s motion was fine in theory, but calculations designed to produce a smooth estimate of position from spiky satellite data turned out to be a very poor source of accurate velocities. The eventual results seemed to make scientific sense, though they were very different from the big arrow marked Benguela Current on the chart. That’s a massive average of the real world mess of little currents and eddies (incidentally I think it was that trip where someone told the engineers that mapping eddies involved sailing uphill: was that in the contract?). It was my only visit to the southern hemisphere so included the memorable experience of sitting on the bridge watching more than fifty albatrosses soaring around us. And my final view of the ship, from another boat transfer into Cape Town, was past rafts of penguins.