Main article: Weather ship
The weather ship MS Polarfront at sea.
Their crews were normally out to sea for three weeks at a time, returning to port for 10 day stretches.[52] Weather ship observations proved to be helpful in wind and wave studies, as they did not avoid weather systems like other ships tended to for safety reasons.[56] They were also helpful in monitoring storms at sea, such as tropical cyclones.[57] The removal of a weather ship became a negative factor in forecasts leading up to the Great Storm of 1987.[58] Beginning in the 1970s, their role became largely superseded by weather buoys due to the ships' significant cost.[59] The agreement of the use of weather ships by the international community ended in 1990. The last weather ship was Polarfront, known as weather station M ("Mike"), which was put out of operation on 1 January 2010. Weather observations from ships continue from a fleet of voluntary merchant vessels in routine commercial operation.