II. Sea Trials - Gulf of Mexico, prior to Aruba

With the mobilization complete, the R/V Persistence and crew set out into the Gulf of Mexico to test all of the equipment to be used during the search for Natalee Holloway's remains. After arriving on site, about 12 hours transit south of Louisiana, we took a SVP (sound velocity profile) to measure the acoustic velocity of the local seawater. Accurate measurements of the sound velocity aid in acquiring accurate sonar data. SVP completed, the side scan sonar is gently lowered into the water with the large winch. A couple steady hands guide the towfish away from the ship's hull to avoid a catastrophic collision, damaging the precious transducers. We anxiously gathered around the primary sonar computer as the first data comes in. Hours of acquisition later, the towfish is dialed in and the data looks very good. The side scan sonar has sufficient resolution to do the work.

The above image is a sample side scan sonar image to illustrate the type of imaging and resolution a high quality digital side scan sonar is capable of acquiring. A wreck (~150ft long 3-masted schooner) is laying upright on the seabed. The dark area to the left of the wreck is the acoustic shadow. A crab trap similar in size and character to the one we will be searching for thought to contain the remains is seen near the bow of the wreck, shown by the black arrow.

After the side scan sonar trials, the ROV (remotely operated vehicle) team and acoustic positioning personnel moves in on location. We moved to a site with about 100ft water depth, adequate to test the acoustic positioning equipment with the ROV. We deployed and calibrated a compatt (computing and telemetry transponder) and then deployed the SeaEye Falcon 1266 ROV. Once in the water, the ROV was tested for telemetry and video functionality. The ROV performed flawlessly.

Seaeye Falcon 1266 ROV (Remotely Operated Vehicle)

Seaeye ROV in action!