Summer 1983 Leeway Drift Experiment.
Abstract
A new method of determining leeway was tested using three life rafts. The method differed from previous methods in that (1) the current was estimated from an array of Lagrangian drifters instead of a single drifter, (2) a land-based microwave tracking system was used to determine positions, (3) two of the life rafts were instrumented to monitor the relative wind at the rafts, and (4) all analysis used the apparent wind relative to the current at the raft. All three life rafts were undrogued, canopied, circular with diameters of 6 to 7.5 feet, empty except for 80 to 100 pounds of equipment, and ballasted. The three ballasting systems were (1) two half-cylinder ballast bags with a 6-inch draft, (2) a toroid ballast system with a 14-inch draft, and (3) a hemispheric ballast system with a 28-inch draft. The method was successful in differentiating the leeway of the lightly ballasted raft from the more heavily ballasted rafts. The leeway speed of the lightly ballasted raft was comparable to results in previous studies. The leeway speeds for the more heavily ballasted rafts were substantially less than those in a previous study. The leeway direction of the lightly ballasted raft was dependent on the raft's orientation to the wind with the two ballast bags acting as a keel. The more heavily ballasted rafts drifted directly downwind. Wind speeds ranged from 2 to 11 knots with waves of 0 to 2 feet and swells up to 4 feet. Keywords: Search and Rescue; Leeway; Life Rafts; Windage.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1985
- Accession Number
- ADA163568
Entities
People
- J. Willcox
- L. Nash
Organizations
- United States Coast Guard Research & Development Center