Leeway Divergence
Abstract
Understanding leeway divergence is key to accurately determining maritime search areas. The downwind and crosswind components of leeway drift as a function of wind speed have been reported on in the literature for 23 categories of leeway drift objects. Two additional leeway drift object categories were analyzed in this report. The optimal relationships between downwind and crosswind components of leeway coefficients and leeway speed and divergence angle values are derived empirically using the 25 categories that contained both sets of coefficients. Downwind and crosswind leeway coefficients were generated for an additional 38 leeway categories based on the estimates from standard error relationships. The entire set of downwind and crosswind leeway component coefficients is presented for 63 leeway categories. The crosswind component of leeway has been observed to be either positive (right of the downwind direction) or negative (left of the downwind directions) for the duration of each individual drift run. For four drift object categories, forty-nine sign changes of the crosswind leeway component occurred during 1332.2 hours of sampling. This represents a frequency of sign change in the crosswind components of 4% per hour, independent of leeway category or wind speed. Crosswind leeway component sign changes at 4% per hour have a significant impact on the final search area probability distribution modeled by Monte Carlo simulations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2005
- Accession Number
- ADA435435
Entities
People
- Arthur A. Allen
Organizations
- United States Coast Guard Research & Development Center