Marine Glossary

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Voluntary Observing Ship

Program of the NWS (or vessel participating in the program) to manage weather reporting by ships at sea and on the Great Lakes. Abbreviated VOS.

The Mariner's Weather Log includes news about the VOS program and related articles about general marine weather. The program operates under the auspices of the WMO (52 countries have VOS programs). The US program is coordinated locally by regional Port Meteorological Officers. There are more than 1,600 vessels (about 15% from the Coast Guard, Navy, and NOAA and 85% commercially owned) and some 10,000 personnel involved.

On board instrumentation includes barometer, psychrometer for humidity measurements, plus sea and air thermometers. Some vessels carry wind instruments, others estimate wind from the Beaufort scale. These data along with sea state, cloud cover, visibility, and ice observations are reported at main synoptic times and additionally at intermediate synoptic times for the Great Lakes and within 200 miles of the US and Canadian shores.

The data are transmitted to the NWS via INMARSAT (satellite communications using a dedicated channel) or via SITOR communications over SSB radio. About 120 vessels use the Shipboard Environmental Data Acquisition System (SEAS) which transmits data through geostationary weather satellites. VOS reports are coded using synoptic weather code FM 13-IX Ship.

See Mariner's Weather Log