Operating an acoustic Doppler current profiler aboard a container vessel

Since October 1992 an acoustic Doppler current profiler (ADCP) has been in near-continuous operation on board a 118-m-long container vessel, the container motor vessel Oleander, which operates on a weekly schedule between Port Elizabeth, New Jersey, and Hamilton, Bermuda. The ADCP collects information on currents from the surface to depths as great as 404 m depending on zooplankton concentrations, ship's speed, sea state conditions, and the ship's load factor. The southbound transits provide more and better data because the ship is loaded and rides deeper resulting in less bubble formation and entrainment underneath the vessel. Installation and operation of an ADCP on a cargo ship has involved a number of factors not typical of research vessels. Providing a data acquisition system that could operate on its own without assistance from the ship's officers and that could recover from problems was the first issue. Isolating and removing electrical transients from the ship's electrical system was extremely challenging. The presence of bubbles underneath the vessel due to variable draft and in heavy weather conditions significantly limits the performance of the ADCP. These difficulties not withstanding, the system is working well and is delivering good data on the southbound legs in most weather conditions and on the northbound legs under more favorable weather conditions. Starling in 1995, differential and attitudinal global positioning system enhancements have made significant improvements to navigational accuracy and ship's heading data.