Blog post

27-29 June 2011: trip to Scapa Flow and calibration!

Published on
June 30, 2011

We left the port of Scheveningen on the 27th of June

On our way to Scapa Flow the crew tested the trawl in the meantime hoping to catch some herring. Despite hopeful faces at the acoustic equipment of the bridge (see picture), they did not catch anything. But the fishing gear turned out to be OK and that is what counts (for the survey anyway).


After a smooth trip, we arrived yesterday (wednesday 29 July) early morning in the Scapa Flow, the calibration site. Kees and Hendrik Jan built the calibration setup. My place was behind the screens, trying to get the calibration sphere in all places of the acoustic beam.

Although the weather conditions were excellent, the acoustic conditions were not so good. On the echogram you can see blotches of weed and fishes(?) that spoiled part of the the calibration (that of the 200 khz transducer). Luckily the calibration of the 38 kHz – the frequency used to estimate the herring and sprat abundance – went OK.

At 18:00 we sailed to our start location 58.16N 2.45W in the Moray Firth. At 9:30 Dutch time we started with the actual survey, heading east on our first transect.