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Tritech Gemini 720is Multibeam Sonar Deployed in Underwater Tanks at York Minster

York based diving and underwater engineering specialists CDMS Sub-Surface Engineering Ltd, purchased a Gemini 720is multibeam imaging sonar in 2016. The sonar has since been deployed by the CDMS team in a range of novel and diverse projects, one of which includes the surveying of underground tanks adjacent to York Minster. These vast underground reservoirs were constructed during the Second World War, so that water would be readily available should the minster succumb to bombing. Remarkably, throughout the duration of the war the minster remained relatively untouched.

The multibeam sonar, which has a range of up to 100m, is installed on the MicroSeaker ROV and provides both visual and sonar data. The sonar's capacity to visualise work areas even in zero visibility conditions means that the challenges present in tasks such as navigation, obstacle avoidance and object detection are significantly reduced or removed. Furthermore, in situations where there are potential hazards, the use of an ROV together with the sonar is a safe alternative to diver deployment.

Mark Dobson, ROV Pilot with CDMS SSE Ltd commented, “The Gemini 720is together with the sonar imagery, provided an enhanced ability to navigate around the vertical support columns. With limited light, the ability to see using Tritech's sonar technology, allowed the project to be carried out quickly, safely and efficiently. Simply put: in many situations we couldn't carry many of the projects we do without the sonar".

Other projects undertaken by CDMS using the sonar, include the location of an end pipe in a reservoir and the surveying of redundant sub-surface sprinkler water tanks.