Robert Allan Ltd (RAL) has developed an electronic device to record high-quality data of tug manoeuvring and seakeeping motions on sea trials, for performance and design analysis
The goal of the Canadian vessel designer is to have a portable kit that can be set up quickly and taken anywhere to collate information that could be used for future design, simulation and operation of tugs.
“This new capability will allow us to demonstrate the accuracy of our computational analyses, to support third-party vessel simulator development or to demonstrate tug performance,” said RAL computational fluid dynamics and ship simulation specialist Michael Shives.
The kit will use a combination of global positioning satellites (GPS) and inertial navigation system (INS) technologies to obtain high-quality motion data.
“We are testing commercial systems including dual-receiver GPS to obtain high-accuracy heading data using algorithms similar to real-time-kinetics, but without requiring a separate base station,” Mr Shives explained.
The systems use either enhanced Kalman filtering or neural-network artificial intelligence to combine data from the INS and GPS systems to give high-accuracy motion data.
“It is critical to record timeseries data of the tug master’s controls to have time-synchronised input and response data,” said Mr Shives.
“This must be done with zero possibility of impacting the vessel control, so we are using footage collected by GoPro cameras and subsequent image processing to convert the collected video to data.”
This provides audio and visual information much richer than a pure data-logger or pure video recording, giving a comprehensive recording of exactly what happened during each sea trial.
So far, two sea trials have been conducted on SAAM Towage tugs in Canada. Manoeuvring data from the agile Salish were used as a benchmark to inform the design of RAL’s new battery-electric ElectRA-2300 tug. This is under construction at one of Sanmar’s shipyards in Turkey, ready for completion this year, and which SAAM will use for similar towage and ship-handling jobs when it arrives in British Columbia.
Data from the escort-specialist Grizzly tug has been compared with RAL’s simulation results with very good agreement, said Mr Shives.
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