Offshore Acoustic and Visual Survey

The Vessel

The R/V Dariabar is an 84 ft. steel hull sailing vessel that was custom-designed by its owner Ethan Silva for marine research work, particularly for bio-acoustic surveys.  Because it can operate under sail, and without generators or other machinery noise, it is extremely quiet, which is important for studying acoustically sensitive marine mammals.  Among Dariabar’s capabilities are extended-range voyages, sleeping quarters for 12, a dedicated science lab, and passive acoustic monitoring equipment (i.e to listen for and process animal sounds received from hydrophones).

Recently, the Dariabar has been specially outfitted with the latest acoustic technologies to conduct passive acoustic surveys. The science lab is equipped with conditioned AC power using high-capacity inverters running off a large battery-bank (for use while under sail). This allows the vessel to run silently under sail power, eliminating issues related to engine and generator noise.   This set-up is particularly useful for deploying hydrophone arrays, which can either be towed or deployed vertically.

The science lab includes a mixing board for signal switching and conditioning.  PC based computers are used to run digital signal processing software, to make digital recordings, and to plot locations of acoustic detections. A VHF antenna for reception of sonobuoy signals is located on the mast-head. In addition, a vertical “sonar-tube” is available for deploying instrumentation into the water from inside the vessel (e.g. such as a directional hydrophone).

The Dariabar also has several specially designed spotter-platforms located on each side of the beam, and high on the masts. These can be used by observers when surveying for marine mammals and other marine life.  A rigid-hull inflatable with a 4-stoke outboard is available for use as a support research vessel (e.g. for biopsy and photo-ID work). Based on our recent deep-water surveys, the Dariabar has proven to be a quiet and stable platform for conducting offshore work on cetaceans.  Planned improvements and upgrades will build upon its existing capabilities.

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