Shifting doors on the Crystal Sea II

With brother Alec carefully controlling the power block from the boat, young David supervises lifting the starboard trawl door....
how many St Ives men does it take to measure the door chains....
under the watchful eyes of David senior, the door gets lifted aboard....
and hung from the gantry....
hundreds of pots wait on the quay for the Emma louise....
with a core-drill on the go, is it possible that the harbour is prospecting for oil in a bid to circumvent the current shortage?