Scapa Flow 2013 Marine Archaeology Project

About the Project

The Scapa Flow 2013 Marine Archaeology Survey Project, commissioned by Historic Scotland, undertook remote sensing surveys and archaeological diving evaluations at some of the sites within Scapa Flow, Orkney and at the Churchill Barriers.

Results from the surveys of several of these sites examined can be found by following the links on the right, and the full technical report can be downloaded using the link at the bottom of the page. Upload of this data was completed with support from Historic Scotland.

The project was completed by ORCA Marine and SULA Diving.

Aims and Objectives

The project aimed to establish or confirm the identification, extent of survival, character and condition of around 28 known but mostly poorly recorded First and Second World War wreck sites, 8 salvage sites, several sites thought to be associated with Second World War Boom Defences, and a limited sample of geophysical features identified in previous studies (Project Adair).

The work built on that of previous surveys including those completed as part of the ScapaMap Project (2001 and 2006) and by Wessex Archaeology Scapa Flow Wrecks Survey (2012), amongst others.

Survey Methods

Remote Sensing Surveys

Remote sensing surveys were completed using a side scan sonar device, which used reflected sound waves to produce an image of remains on the seabed.

The side scan surveys were completed with a C-MAX Sonar CM2 Digital Towfish. A medium frequency setting of 325 kHz was used,with the range set to either 50m (9.1 pings per second) or 75m (7 pings per second) depending on the target site. This resulted in either a 100m or 150m swathe during each run, at a resolution which enabled the technician to distinguish both wrecks and smaller objects such as mooring ropes, anchor chains and anchors from the seabed.

To increase manoeuvrability, the towfish was pole-mounted during some of the scans of the blockships at the Churchill Barriers.

Spatial data was collected using an Evermore SA380 Marine GPS attached to the winch or the pole. When towed, the layback of the towfish was calculated using a pulley counter making it possible to determine the location of the towfish (and thus the site) relative to the boat to within 5m. When pole-mounted, the position of the towfish in relation to the boat is precisely known. Thus the location of site can be determined to within 3m accuracy as per the accuracy of the Evermore GPS.

Diver Surveys

Where contacts were identified and past survey information about the condition of the remains was limited, divers were sent down to look at the remains from each site to assess their survival, identification, character and apparent condition. Unless a known buoy was present on the site, a shot line was deployed on the target coordinates or nearest clear contact identified on the side scan. The position was determined using an Evermore SA380 Marine GPS (approximate accuracy 3m).

Video footage of the dive and photographs of key features observed were taken and the footage reviewed by a marine archaeologist and marine historian.

Resources

Scapa Flow 2013 Marine Archaeology Survey Project: Final Report

Project Contributers

Annalisa Christie, Kevin Heath and Mark Littlewood compiled the report. In addition Malcolm Thomson, Brett Green, Toby Tibbitts, Keith Rendall and Barry Kenyon completed the side scan and diving surveys, facilitating the data collection.