The Barny Sentinel trawl-resistant ADCP bottom mount: Design, testing, andapplication

A trawl-resistant bottom mount (TRBM! has been developed to meet the needs of long-term deployment of acoustic Doppler Current Profilers (ADCPs) and W ave-Tide Gauges in water depths up to 300 m, This paper describes the unit' s construction and operation together with practical lessons learned during development, testing, and use that can be applied to comparable platforms. The Barny Sentinel is derived from a larger version de developed several y ears ago at SACLANT Center, now extensively redesigned to incorporate an RD I Sentinel ADCP and a Sea-Bird Wave-Tide Gauge. A concrete ring surrounding the fiberglass instrument housing serves as ballast and impact protection. Two independent recovery modes may be activated by acoustic commands, one of,which can operate whether or not the platform is upright. Features have also been included to facilitate recovery by remotely operated underwater v ehicle, A sending unit, temporarily attached during launch, pro,ides real t ime information on platform depth and tilt, and confirms that the platform is properly positioned on the bottom before a launch commitment is made. ii series of tests and applications have validated all basic functions and tr awl resistance, Platform cost has been kept below. that of the on-board ins truments, while still maintaining the required high level of recoverability .