Searching the Sound

Side scan of the Buitenzog, provided by School of Ocean Sciences at the University of Wales (Bangor). In cooperation with the School of Ocean Sciences at the University of Wales (Bangor), SOMAP undertook some remote sensing surveys within the Sound of Mull in August 1999. The principal objectives of this work have been to identify new wreck sites, to record existing ones, and to examine sediment transport and environmental conditions within the Sound. Additional side scan work has been undertaken by the Archaeological Diving Unit of St Andrews University.

Above right: Side scan of the Buitenzog, provided by School of Ocean Sciences at the University of Wales (Bangor) – click for full size image.

Techniques used

During surveys in 1999 aboard the diving vessel Gemini Breeze, we deployed both side scan sonar and a proton magnetometer. The side scan sonar incorporated a high (100&325khz) dual frequency towfish connected to a CM-800 recording system, displaying data on a VGA screen. The proton magnetometer system was a high resolution tow system connected to a Scintrex MP-3 proton magnetomoteter. We fixed positions of anomalies using differential GPS, supposedly allowing +/- 10 metre accuracy.

Areas targeted

This project looked at Ardtornish Point, Fishnish Bay, Scallastle Bay, and Duart Bay, as well as the wrecks of the John Preston, Buitenzorg, and Swan.

Problems encountered

Side scan of the John Preston site, provided by School of Ocean Sciences at the University of Wales (Bangor). We experienced problems with position fixing due to transmitter irregularities and had to rely on standard GPS. Magnetometry also proved to be problematic. This was probably due to the existence of large background geological anomalies resulting from the extensive Tertiary igneous rock in the area. This made the identification of high frequency anomalies consistent with shipwrecks fairly difficult.

Main findings/achievements

Side scan image of the Hispania, by the Archaeological Diving Unit. Good quality data sets were obtained of whole and broken up shipwrecks. No ‘new’ wrecks were located, although a few were rediscovered and position fixed. We did locate several interesting anomalies in Scallastle Bay which will require ground-truthing by SOMAP divers in the future. Rippled beds identified in the south of both Scallastle and Duart Bays suggested sediment transport pathways in an easterly direction. Side scan also picked up pathways associated with scallop dredging operations.
Above right: Side scan image of the Hispania, by the Archaeological Diving Unit – click for full sized image.

Acknowledgements

Jim Bennell, Doug McElvogue, and Tim Collyer of School of Ocean Sciences at the University of Wales (Bangor); Martin Dean and Mark Lawrence of the ADUS, St Andrews University.

All black and white images have been provided by School of Ocean Sciences at the University of Wales (Bangor). The colour image of the Hispania was provided by the Archaeological Diving Unit of St Andrews University.