If you want to know what the weather's going to be you've got loads of ways of finding out.
You can watch the tv & see on the news. Maybe read it in the newspaper or just pick up your smartphone,
check a website or download a dedicated weather app.
If you're on a ship out at sea, however, it becomes a little harder. You won't have mobile reception so you can't access the internet.
Newspapers obviously can't be delivered and even if you can pick up tv reception, chances are
they're not routinely broadcasting the maritime weather anyway. Instead we turn to a technology
that's been specifically developed for use at sea. Navtex. Navtex means navigational telex and it's a
system that allows reception of navigational and meteorological warnings and forecasts. It forms
part of the GMDSS or Global Maritime Distress and Safety System. Under the safety of life
at sea convention, it is a mandatory piece of kit to be carried on board any ship that proceeds to sea.
The concept is that the world is divided up into nav-areas, with warnings and forecasts
issued for each area by coastal states. There are a whole host of different subjects that can be
transmitted by Navtex. Within the unit itself you just select which ones you want to receive.
A, B and D, so: navigational warnings; meteorological warnings; and search and rescue information, can't
be turned off but all the others are optional. l is another one that shouldn't be turned off but is
usually programmed as optional in most receivers. You then need to tune into the transmission
stations to receive the actual broadcasts. Let's take Northwest Europe as an example. You get maps
like this which show broadcast stations and their approximate range of transmission. Each
station has a letter for either the international or national broadcast so all you need to do is
put the appropriate letters for your passage into your receiver. Now, as we're specifically focusing
on weather forecasts in this video let's take a look at an example. We'll use the UK, so we know
it's going to reference the shipping, or weather, areas that are used in the shipping forecast.
You may well have seen this map before. All it does is break down the whole area into smaller chunks
to give better more relevant information. These areas actually pre-date Navtex, having originally
been established for voice broadcast rather than the textual version we're talking about today.
Anyway, when the forecast comes the Navtex receiver starts to print it off. Some will just save it to
memory now but traditionally they always print straight away. On this forecast the first section
gives the overview. It's from the 15th of September 2020 at 03:00 UTC. The forecast itself covers 06:00
on the 15th until 06:00 on the 16th, so it's a 24-hour window. After that it moves into
the general synopsis which just gives a broad overview of the prevailing conditions before
moving straight on to the meat of the forecast where it breaks it down into the individual areas.
Viking, North Utsire, South Utsire. Those are just the sea areas from the map that we covered a
few seconds ago. Southerly or Southeasterly, 3 to 5, bearing northerly 5 to 7 later.
Perhaps gale 8 later in North Utsire. That's the wind referenced to the Beaufort scale.
Rather than giving the speed in knots the Beaufort scale breaks it down based on the effects that it would
have on the old sailing frigates. Each level would correspond to a different amount of sail
that they could hoist. Slight or moderate, occasionally rough later. That's the sea state
references to the Douglas scale. Just like the Beaufort scale does for wind, the Douglas scale links different wave heights to a standard scale.
It gives descriptions of the conditions rather than numbers, which could be easily confused with the wind forecast.
Rain. That's just a description of the prevailing weather conditions. You could have anything like fair, showers, rain,
thundery showers, fog patches. It just gives you an overview of the conditions itself.
Moderate or good, occasionally poor. That's the visibility with reference to the met office's scale.
Again, giving the description here means it's harder to confuse it with the wind, the sea state
and the weather. The rest of the forecast just continues working through all the other sea areas .
So we've looked briefly at Navtex, but how else could ships get this same information?
Taking the shipping forecast as an example, normal radio stations and the coast guard do read it out.
You could even download it online nowadays, though once we branch out into internet forecasting we
can actually get far more detailed ones than just the shipping forecast. We can get full-on weather
routing information instead. These usually run as a computer program where you can input your passage.
The weather forecast is then sent to your computer as a small file through the internet. It lets you
play through your passage checking the weather, the sea state, the visibility and things with reference
to your ship's actual position. Some services go one step further and they do the actual weather
routing for you. On an ocean passage you could tell them your start position and your end position and
they'd work out a number of different options for passages you could take.
You can probably already see the possibilities with sophisticated weather routing programs and services.
Safer passages, fuel savings, and less chance of cargo damage to name a few.
Even though more and more ships are being equipped with satellite systems for accessing the internet, GMDSS (and Navtex in particular)
still remains the official way for ships to receive weather updates and information.
And that brings us to the end of today's video. If you enjoy content like this be sure to subscribe and turn on
notifications to know whenever I post new content. Until next time, thank you for watching, and goodbye.