Researcher 3/71

Cruise summary report

Cruise Info. 
Ship name (ship code)Researcher (3175)
Cruise identifier3/71
Cruise period1971-05-14 — 1971-06-07
Port of departureBarry, United Kingdom
Port of returnBarry, United Kingdom
1. To continue the IGS programme mapping the geological structure of the continental shelf.
2. To test a sparker system with a new hydrophone to assess the capabilities of the hydrophone in deep water and its suitability for use with airguns.

Sailing was delayed due to the fitting of the automatic steering and gyro compass. Survey work started on the 14th May and continued without break until the 21st when the ship returned to Barry for a replacement Trigger Unit losing 12 hours of survey time. Survey work then continued until 24th May. Good weather enabled over 2250km of profile to be surveyed covering about one third of the survey area. The ship docked in Waterford on the 24th May for maintenance and sailed again on 26th May.

The ship sailed west to undertake hydrophone trials over the continental shelf but adverse weather and engine failure caused a delay. The trials were successful and seismic records were obtained using a sparker (6000 J) in up to 2000m. Gravity and magnetic measurements were taken in the outward and return journeys.

Routing surveying recommenced on 29th May and continued until the 6th June. Water depths were computed from seismic records for two days. The total length of the survey completed was 4250km.
Chief scientistMichael C Tully (Institute of Geological Sciences, Edinburgh)
Cruise reportResearcher 3/71 cruise report researcher3_71.pdf (0.29 MB) 
Ocean/sea areas 
GeneralBristol Channel
Specific50.2-52N 08.00-04.00E
Geology and geophysics 
Multi-beam echosoundingQuantity: track kilometres = 441
Long/short range side scan sonarQuantity: track kilometres = 2487
Single channel seismic reflectionQuantity: track kilometres = 5643
Gravity measurementsQuantity: track kilometres = 5643
Magnetic measurementsQuantity: track kilometres = 5643