HMS Colossus geophysics survey 2005


On Saturday 16th April a small team of CISMAS volunteers travelled over to the Isles of Scilly to continue work on the Colossus Project, namely, Kevin Camidge, Brendon Rowe, Luke Randall and myself. We were joined by Pete Holt who provided the software, Site Searcher - as well as the training required to use it. The aim of the week was to carry out a second geophysical survey, on areas not previously covered by the ADU in 2002 - once again using a magnetometer, whilst additionally carrying out a sidescan sonar and bathymetric survey.

On arrival, the first task was to unpack all the equipment, check that it was in good order and assemble it to a degree that would allow it to be transported to the boat the following day. Dave McBride, another CISMAS member from IoS kindly offered the use of his boat Predator.

Sunday 17th: We loaded all the equipment onto Predator and the set-up process began.The laptops, GPS, magnetometer power unit and peripherals were installed in the wheelhouse (suitably fastened down), two 12V batteries to power them were housed just outside in a crate on the deck and the transducer for the sounder was securely set in place, bolted and lashed to the hull structure. The magnetometer was laid down with all its cabling at the stern, as was the sonar sidescanner - ready for deployment. Once happy with the set-up, having checked all connections were working, we powered down and the daily ritual began of taking the batteries and laptops back to shore; the former to be recharged and the latter to be used in the evenings for data processing etc. Tania Weller, a CISMAS member working on Scilly offered her premises for the battery recharging, which we gratefully accepted as she lived near to the quay and it would save us lugging them to and fro, a mile each way on foot to our accommodation at Porthloo.

Monday 18th: 09:15 start from the quay. The weather though imperfect, was acceptable, so loaded with waterproofs, food, laptops, batteries etc. we trooped aboard en masse, and set off. Once set up and out in the search area, we deployed the magnetometer for real, towing it behind the boat, its depth regulated by a large fender attached to its cable and its lay back position established by the length of the cable. Despite expecting the day to be just a trial run, we found that we collected a large amount of acceptable data and much to our delight, managed to complete an entire search area. Minor tinkering possibilities with the Site Searcher program were noted by Pete Holt and he resolved to spend some time during the next day addressing them.

Tuesday 19th: Pete stayed on shore in the morning tweaking the software, leaving Kevin and Bren to get to grips with running the search program. Luke was in charge of cabling and deployment whilst I kept a written log of each run, any anomalies and/or actions taken throughout the day. Dave did a fantastic job of keeping Predator on course in a lumpy sea, up and down the search lines indicated on the laptop screen - linked to the GPS. Pete rejoined us in the afternoon with adaptations to the software and the data collection continued.

Wednesday 20th: I stayed on shore and made a start on processing the massive amount of data so far accrued. Luke had training in running the search program on the boat and another successful day of data collection ensued. The weather and sea conditions were good and all the proposed search areas for the magnetometer were completed. The sonar sidescanner was then setup and having finished the planned side scan, the boat finished for the day.

We had at this stage completed our brief for the week well ahead of schedule, so we decided in the evening to try a few extra searches for the following day - weather permitting. Kevin set up an additional search area for the magnetometer and another for the sonar sidescanner.

Thursday 21st: The four of us went out on the boat with Dave whilst Pete stayed on shore. The weather however was not so kind to us and a combination of the wind, currents and waves made the planned search pattern very difficult to follow. By early afternoon we decided to call it a day, and headed back for the harbour, having not managed to get an additional sonar sidescan. But we were far from disappointed with our overall achievements.

Friday 22nd: The gear was all disassembled from Predator and brought ashore. We washed off the magnetometer, sidescanner and cabling with fresh water, utilising the bathroom shower through the window! Then we re-packed it for shipping back to the mainland. We spent a relaxing evening in the Scillonian Club where we had arranged to have dinner with our Scillonian counterparts who had offered their help throughout the week.

Saturday 23rd: Final packing of our belongings and cleaning of the rented accommodation had us in a flurry of activity until 10:00. Then Dave arrived, kindly offering to transport the crated and heavy equipment to the quayside in his car. Our other main baggage was left by the roadside for the Island carriers to collect and we trotted off to Hugh Town to while away the rest of the day until the 16:30 ferry. Once again we were beholden to Tania who allowed us to leave our hand luggage at her premises (video camera, daypacks, laptops etc.) which meant that we were unencumbered for the rest of the day until boarding the ferry.

Project Review: Overall an unqualified success. We achieved everything we set out to do plus a little bit more. The solid grind of data processing has yet to be completed and will involve many hours of work. It is hoped to identify exciting possibilities for hitherto undiscovered new targets on the Colossus site - to be investigated in September when CISMAS plan to carry out dive searches. On average we spent 8 hours per day on the boat and must have walked at least 6 to 7 miles each day, sometimes well loaded up with equipment. I have to say that I, for one, thoroughly enjoyed the experience even though at times it was wet, cold and tiring.