Marine forecasts: where to get them and how to read them
Get and read a marine forecast: shipping and inshore waters forecasts, VHF, NAVTEX and GRIB files, the exact words, pressure charts and satellite images.
How the lesson starts
MSI, Maritime Safety Information, is the forecasts, the gale warnings and the navigational warnings for ships. The MCA is responsible for it, and the Met Office prepares and issues the forecasts and warnings in it.
There are two approved ways of sending it out: NAVTEX, a receiver on board that prints or shows the messages, and EGC, Enhanced Group Call, which sends them to ships by satellite.
The internet is not part of the MSI. It is useful, but the Met Office says it should never be relied on as the only way to get the latest forecasts and warnings.
The shipping forecast
The waters around the British Isles are divided into 31 sea areas. The map shows the four in the Channel.
The Met Office issues the shipping forecast four times a day, at 2300, 0500, 1100 and 1700 UTC, and each covers 24 hours from 0000, 0600, 1200 and 1800 UTC.
Gale warnings, for winds of force 8 (34 knots) or more, or gusts reaching 43 knots or more, are issued as required, as soon as possible after they are received, and are valid for 24 hours unless cancelled. The stronger words count the same way, the mean wind or the gusts: severe gale, force 9 (41–47 knots) or gusts reaching 52–60 knots; storm, force 10 (48–55 knots) or gusts reaching 61–68 knots; violent storm, force 11 (56–63 knots) or gusts of 69 knots or more.
What you practise inside
- Where forecasts come from
- Reading the forecast2 exercises
- Charts and satellite2 exercises
This is a preview. The lesson itself is interactive: you work through it step by step, and every answer is checked as you go.