By Richard Chiverrell
2-3 days ago the RRS James Cook voyaged towards the deeper waters of the Porcupine Bank, a lesser known quarter of the continental shelf off western Ireland. Leaving the coastline of Donegal and Mayo in our wake for our remote destination 213,000 m west of dry land, but with key essentials to sustain us. Stocks were replete with plentiful willpower, pineapple juice, fresh water, vibrocore tubes, melon, bacon and eggs. As we progressed south the harder grounds that lay ahead, our target to sample the sediment of the seafloor continues to make mince-meat of the steel core-catchers. We use these to ensure the valuable muds and shells do not fall out of the vibrocore chamber as we return it to deck after the radio call sign ‘….bottom operations are completed, over, roger…’. The core catcher is an ingenious device that fits into the base of the vibrocore tube, as we hammer into the sediments its’ metal talons open to allow material to enter the vibrocorers’ lair, but then grip tight there should be no escape….. Science team have however been confounded and are confounding the BGS crew by their selection of hard and sticky sediments, which attempt to escape under suction as the vibrocorer is retracted from the sea floor before recovery to the ship. This destroys core catchers it appears at will…..
Stock check, eight sciences days to go, one transect remaining, 70 vibrocore tubes, 33 core catchers and 45 targets for sampling. This maths does not stack up…. In mission control concern is rising about our supplies of core catchers, particularly as night team chew through three in two core sites) leaving Donegal Bay(two in one core to catch this stuff, Science Team are picking well, we have diamict, but this is seriously tough stuff. But on Porcupine Bank there is no hardware store, no core catcher shop, we are on our own…. Brains were being exercised, contingencies discussed, meanwhile the BGS scoured their stocks, NOC’s piston core team’s and the RRS James Cook materials on board; was there a way to make extra core catchers?….. The piston core catchers, what about them…. the wrong size and a different fit to the chamber….. so near but so far…. Again it was the BGS crew to the rescue as Garry, Iain, Connor, David, Claire and Apos exercise their ingenuity and welded new, more resilient tougher core catchers using the spare parts from torn, contorted remnants of the existing broken one’s and parts from piston core catchers. Once tested and in production, they can make them in 5-10 minutes… If successful this might see us through the target list of sites for the Galway Bay and Porcupine Bank transect…. Night shift see the first deployment of the ship-made catchers, and they work well and survived three-four visits to the sea floor compared to one currently by the less robust originals. A huge sigh of relief from Science Team, and a well earned pineapple juice for the BGS….
Credits: Photography by Alex Ingle (except for the badly lit one by me)