HMS Colossus: debris field survey 2004

It is difficult to make any conclusive statements about the Colossus debris field at this stage of the project. There are still magnetic anomalies identified by the ADU survey to be investigated. Furthermore the ADU survey does not cover the whole of the designated area; clearly we must wait until the debris field project has been finished before proper conclusions can be reached. That said, it is already apparent from the work so far that much material from Colossus lies outside the current designated area and as such is not ‘protected’.

There is also evidently a cluster of material, including three guns (Guns 7,8 & 10) lying to the south east of the stern of Colossus which indicate that the debris field is more complex than the hitherto perceived debris trail between Roland Morris’ old site and the stern site. See the plan of the targets identified.

The Colossus anchors are another potentially interesting part of the story. We know from Murray’s account that Colossus deployed all three of her bower anchors prior to her loss. One, at the original anchorage in St Mary’s Roads, was lost when the cable parted. We are also told that Colossus was riding to the other two on ‘half a cable’10 when she foundered. Locating any of these anchors would give invaluable information concerning the position of the vessel. None of the Colossus bower anchors has yet been located. The three anchors noted by Morris as leading him to the site are all far too small to have been bowers from Colossus11. The largest of the Morris anchors had a recorded shank length of only 3m. The bower of a 74 had a shank length of 18’6” (5.63m)12. Unfortunately we know that at least one of the Colossus bowers was recovered in contemporary salvage of the wreck13 and the possibility that the other two were also salvaged must be considered. That said, should any of the bowers from Colossus remain on the seabed their location would offer invaluable information.

By conducting a systematic survey of the whole area around Colossus some estimate of how much material remains and just how much has been salvaged will be gained. This will be particularly true for the larger iron objects, guns and anchors where it should be possible to detect all such objects by finishing the magnetic survey started by the ADU (phase II of the CISMAS project).

10 A cable is defined as 120 fathoms, however Bellona, a sister ship of Colossus, had seven cables on board, all of 100 fathoms (Lavery The 74-Gun Ship Bellona 2003)

11 Wessex Archaeology Colossus DBA 2003 and original notes by Slim Macdonald

12 Lavery The Arming and Fitting of English ships of War 1600-1815.

13 Wessex Archaeology Colossus DBA 2003 – 3.2.20 p13.

Project outline
ADU magnetometer survey
Wessex Archaeology survey
Project methodology
The targets
Targets investigated
Targets identified
Plan of the targets identified
Summary of anomalies investigated
Anomalies yet to be investigated
The photographs
Appendix 1 -Magnetic anomaly graphs
Appendix 11 -Colossus debris field survey - diver record sheet