unrestricted use, copyright acknowledgement
Geophysical Survey WESSEX2B: (09/Aug/2005 to 19/Aug/2005)
Available under the Open Government Licence subject to the following acknowledgement accompanying the reproduced Wessex Archaeology materials "Contains Wessex Archaeology materials ©Wessex Archaeology [year]"
CP2 Regional Sea Boundaries: Eastern Channel, Offshore 1:250k: Wight, SeaVoX Sub-Ocean: ENGLISH CHANNEL
Wessex Archaeology (WA) was commissioned by English Heritage (EH) to undertake geophysical surveys as part of the project entitled ‘Wrecks on the Seabed: Assessing, Evaluating and Recording’, supported by Round 2 of the Aggregate Levy Sustainability Fund (ALSF). The specific aim of this project was to provide industry, regulators and contractors with guidance on the archaeological assessment, evaluation and recording of wreck sites. ‘Assessment, evaluation and recording’ are taken to include various methods of archaeological investigation that are intended to improve the understanding, preservation and appreciation of the historic environment. Geophysical surveys were conducted over five wreck site areas. This archive relates to the geophysical survey over the Liberator, an unknown wreck, and the submarine U86. Sidescan sonar and magnetometer data were acquired from the vessel Wessex Explorer on the 9th and 12th August 2005 and the multibeam echosounder data were acquired on the 15th and 19th August 2005. The geology and geophysics component of the data are archived at British Geological Survey (BGS) MEDIN Data Archive Centre (DAC) for Geology and Geophysics. Data were also provided to other archive centres as appropriate.
Navigation was provided by a Fugro Omnistar 8300 HP GPS receiver, with corrections provided via satellite subscription service which gave a positional accuracy of ±10cm. Multibeam bathymetric data was acquired by Netsurvey Ltd. using a Reson 8125 Multibeam echosounder and a MHARS motion reference unit and gyro. Sound velocity profiles were recorded at the start of each multibeam survey and then as required during the survey. The raw bathymetric data were processed Netsurvey Ltd, in order to apply tidal corrections and remove any spikes in the data. A Klein 3000 dual frequency digital sidescan sonar, which operates at both 125kHz and 445kHz simultaneously, was used for all sidescan surveys.The magnetometer data were acquired with a Marine Magnetics Explorer Proton Magnetometer towed 10m behind the sidescan sonar towfish.