Performance of GPS/Argos self-locating datum marker buoys (SLDMBs)

The U.S. Coast Guard Research and Development Center is developing and testing satellite tracked drifters to supersede the Datum Marker Buoys which are tracked by a radio direction finders onboard USCG aircraft. The new drifter, known as the self-locating datum marker buoy (SLDMB), is based on the Coastal Ocean Dynamics Experiment (CODE)/Davis design, modified to allow deployment from USCG fixed and rotary wing aircraft. SLDMBs are positioned using the Global Positioning System (GPS) with data telemetry through the Argos System. Performance tests were conducted to determine drift characteristics, air drop and water deployment procedures, time to first position fix, and survivability of the SLDMBs. Three air drop tests were conducted to insure proper air deployment and in-water self deployment of the SLDMBs. Two sea trials, one under moderate conditions and one during heavy weather, were conducted to examine data reception and transmission, as well as survivability of the SLDMBs.