The visibility of the water, its depth and temperature make it extremely difficult to carry out extensive diver measurements...
In early 2001, the ScapaMAP Acoustic Consortium (SAC) was formed with the aim of augmenting the project's other work with acoustic remote sensing data. The visibility of the water, its depth and temperature make it extremely difficult to carry out extensive diver measurement of the ships. Consequently, the only way to quickly map all of the wrecks and surrounding area to reasonable accuracy is to use an acoustic instrument.
Above: the survey vessel Scimitar.
Previous work has used sidescan sonar and shallow water multibeam equipment to provide medium resolution bathymetry and high resolution acoustic backscatter for the area. SAC chose to use a new, dynamically focused, very high resolution multibeam echosounder, the Reson 8125, to provide the highest resolution data of the wreck and surrounding area to date.
The survey system provided by the SAC members consisted of the Reson 8125, a TSS POS/MV 320 attitude and navigation system, and a Racal Landstar DGPS receiver, installed aboard the S/V Scimitar operated by the Archaeological Dive Unit bases at St Andrews University. The survey was carried out from 13-16th June 2001.
Following discussions between Historic Scotland, the Maritime Coastguard Agency's Receiver of Wreck and SULA Diving it was proposed the ETV Anglian Sovereign be used to conduct a second remote sensing survey over the Scheduled sites in Scapa Flow. The objectives were to determine if this technique could be used for rapid site assessment to edit changes and to extend the survey area to cover the salvage sites. The Anglian Sovereign is used for hydrographic surveys in support of the UK Civilian Hydrographic Programme when not in use as a towing vessel, and is permanently equipped for this purpose.
Above: the Anglian Sovereign.
The Anglian Sovereign was equipped with a Reson 7125 Multibeam Echosounder (MBES) system, Applanix POS/MV 320 V.4 GPS-aided Inertial Motion Unit (IMU), CSI DGPS MAX receiver, Fugro SkyFix.XP Satellite Precise Point Positioning system, SeaBird SBExx Conductivity, Temperature and Depth (CTD) probe, Pressit ND16-60 draught sensor. The survey suite was configured to send all data to the data capture computer with storage on an external Network Attached Storage (NAS) device. Timing signals were led from the POS/MV to the Reson TPU so that data time-tagged as source could be used for combination of data.