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weather - page 1

8.1 Forecast

The HNMS (Hellenic National Meteorological Service) issues a weather forecast for the following hours, updated every three hours. You can get a forecast from the HNMS web site or other similar web sites or on marine VHF radio. The forecast includes a detailed analysis of weather systems, gale warnings, sea area forecasts and coastal station reports for the following hours for the waters around any place you would like to visit.

Useful web sites:





The wind and the sea state are probably of the most interest, so let’s kick off by finding out exactly what is meant when we are told that the wind will be Force 6.

Here are the major sources or weather information:

  • VHF radio, fixed mounted or hand held

  • On-line Internet access

  • Weather fax

  • Television and radio stations

  • Smart phone and Device Apps 

  • Subscription services for serious sailors wanting accuracy

Beaufort scale

Admiral Beaufort published his wind scale in 1808 so that Royal Navy captains wouldn’t keep damaging expensive sails that cost the Admiralty a fortune! It was so successful that it remains, to this day, the internationally accepted method for classifying wind speeds. An updated version that gives guidance for small sailing and power craft is shown in PDF 8.1.1. The wind strengths are average wind speeds, not the maximum that can be expected. Taking things to the extreme, a Force 4 may give gusts of up to 20 knots if it is squally, and if there is a 3-knot tidal stream flowing in the opposite direction, the apparent wind felt will be 23 knots – a Force 6! An unexpected 5-hour leg to windward with this wind-over-tide situation may be impossible for many power craft and an endurance test for even an experienced yacht crew. If you are relatively new to the sport and have chartered a boat for a weekend that turns out windy, try to resist any peer pressure that may push you to set out against your better judgement. Tragic accidents have happened in the past when novice skippers were persuaded to venture further than wisdom dictated. Keep your resolve and make alternative plans to explore the sheltered creeks close to base instead.


PDF 8.1.1

Strong wind warnings and gale warnings

Strong wind warnings are issued when the winds are expected to reach Force 6. Gale warnings are broadcast on marine VHF and Navtex as soon as possible after they are issued, and those with Digital Selective Calling (DSC) radios will hear a safety alert before the voice message is broadcast. The warning will be issued for specific sea areas when winds are expected to reach Force 8 or to give higher gusts. A ‘soon’ forecast will generally give the coastal sailor time to reach shelter.

Other wind scales

The Beaufort Scale is an empirical measure that relates wind speed to observed conditions at sea or on land. Its full name is the Beaufort wind force scale. Except the Beaufort Scale the wind speed can be measured in knots, miles per hour and kilometres per hour.


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