Sea Trial Data: Recording the Big Picture with a Small Kit

January 18, 2023

by Michael Shives, P.Eng., Ph.D.

Robert Allan Ltd. is actively developing our in-house capability to collect tug motion data on sea trials.

The goal is to have a portable kit that can be set up quickly and taken anywhere in the world. Operated by one or two people, the small kit will give Robert Allan Ltd. the capability to collect high quality data for tug maneuvering and/or seakeeping motions. This new capability will allow us to demonstrate accuracy of our computational analyses, to support third party vessel simulator development or to demonstrate tug performance.

The kit will use a combination of GPS and Inertial Navigation System (INS) technologies to obtain high quality motions data. We are testing commercial systems including dual-receiver GPS to obtain high accuracy heading data using algorithms similar to real-time-kinetics (RTK) but without requiring a separate base station. The systems use either Enhanced Kalman Filtering or neural-network AI to combine data from the INS and GPS systems to give high-accuracy motions data.

It is critical to record timeseries data of the tug master’s control inputs to have time-synchronized input and response data. 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 datalogger or pure video recording, giving a comprehensive “big-picture” recording of exactly what happened during each trial.

So far, two sea trials have been conducted on local SAAM Towage tugs. Manoeuvring data from the agile Salish were used as a benchmark to inform the design of Robert Allan Ltd.’s new battery-electric ElectRA-2300 tug that SAAM will use for similar jobs. Data from the escort-specialist Grizzly tug have been compared to Robert Allan Ltd. simulation results with very good agreement.