Spring 1985 Leeway Experiment
COAST GUARD RESEARCH AND DEVELOPMENT CENTER GROTON CT
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The U.S. Coast Guard R and DC and Florida Atlantic University FAU conducted an experiment off the east coast of Florida during March and April 1985 in order to determine the leeway of various craft common in Search and Rescue SAR situations. Leeway, defined as the response of a survivor craft to the effect of wind alone, is an important component of the total drift calculation for a survivor craft. Other components are the sea current, tidal current, and wind-driven current. Leeway data will be utilized by search planners to predict the movement of various search targets. The search targets evaluated were three types of 4-man life rafts, one 6-man life raft, and three types of small boats less than 21 feet in length. This report presents results of the R and DCs statistical analysis. Results of FAUs use of the data to calibrate and test a numerical model are presented separately, DOTOSTP-3487058, August 1986. Leeway was calculated as the difference between the test crafts velocity and the average current of the upper three feet of the water column. The oceanic surface current at the test craft was determined from an array of drifters surrounding the test craft. The drifters and small craft were tracked by a Microwave Tracking System MTS. The wind was measured onboard the small craft at a height of six feet above the ocean surface. The apparent wind relative to the current at the raft was used in the analysis. life raft, drogue, leeway.
- Escape, Rescue and Survival