Monterey Bay Aquarium Research Institute

ALTEX Arctic Cruise
October 7 - November 7, 2001
Tromso, Norway to the Arctic Circle
Logbook

October 10, 2001: Day #4
At Sea


Mike Pinto writes: The day started with breakfast at 7:00 am of pancakes, eggs and cereal. Today’s tasks included preparing the vehicle for launch, and to test the radio data communications calibration, calibrate the ship’s radio directional finder (RDF) used to track the vehicle on the surface and to run some short missions with the mid-sized vehicle. Monday’s tests indicated that the RDF was not accurate in locating the position of the AUV

The first test was to put the AUV in the water with the RHIB (rigid-hull inflatable boat), move the Healy approximately 1 km away, rotate the Healy 360 degrees in place as we check data communications and calibrate the RDF by measuring the ship’s relative heading to the AUV against the measurements of the RDF. We all moved to our positions - spotters were located at several positions to visually track the vehicle, Jim Bellingham on the bridge recording RDF and heading data, Mark Sibenac on the bridge monitoring data communications and Bill Kirkwood keeping the AUV company in the RHIB. The test was successful in communicating with the vehicle (although there were some weak signal areas) and determined the RDF calibration.

The next step was to run a short mission. The vehicle was programmed to dive 15 meters and run at 3 knots for three minutes. We could see the vehicle move out and dive below the surface. The hydrophone system tracked the vehicle while we waited for it to surface. After surfacing, visual contact was made but only a small amount of data was transmitted back to the Healy before the communications link failed. The AUV was retrieved and the data was reviewed after the hard data link was established.

After dinner the science team met for its regular 18:00 meeting. Rob McEwen reviewed some of the early analysis of the on-board data that indicated a problem with the rudder control surface behavior (the vehicle possible spinning donuts?). Several ideas were tossed about and the AUV operation team and the data group went back to the lab to work on the problem. Upon inspection of the vehicle, the team determined that a rudder servo arm connection was disconnected and a small amount of sea-water was discovered in one of the battery control circuits. The team suspects that the AUV rudder servo connection may have been damaged inadvertently by being struck by the RHIB boat during the earlier testing in the day. It appears the sea-water corroded a connection that may be the cause of the communication problem. So as the day ended for me, the vehicle was being repaired and readied for the next phase of testing.



Bill Kirkwood helps coordinate Dorado's deployment from one of Healy's RHIBs.


 

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