Sulmara was commissioned to deliver trenching survey data without the requirement for a survey support vessel. As part of this five-month project live “as-built” data during trenching was essential. While working in the Gulf of Mexico, Sulmara was able to improve the speed of delivery of “as-trenched” survey work, as well as reducing overall vessel time spent, by performing simultaneous trenching and survey operations.
By reviewing the standard methodology, the Sulmara survey team identified that the vessel configuration would allow the WROV c/w dual head R”Sonic 2024 to fly behind the jet trencher, at a suitable offset, to allow trenching and the “as-trenched” survey to be completed in a single pass. Positioning algorithms were employed to allow extended layback ROV operations whilst auto processing techniques allowed DoB calculation, based on pre-trench pipe position.
This not only negated the need for a separate survey pass, but also enabled the project engineers and trenching supervisors to access data relating to the performance of the trencher in (almost) real-time, thus facilitating effective decision making and fostering confidence in trencher performance.
The Drix USV (Uncrewed Surface Vessel) was deployed using a circular mode programming to support the positioning of the ROV. However, the analogue signal proved problematic in an environment with a lot of other background “noise”. However, with adjustment and perseverance Sulmara managed to deliver the positioning data required to keep the ROV on track.