Communications Equipment for the Sailor

Used for communication of weather and other Marine Safety Information from MRCCs. Range is limited by the nature of the signal, effectively, to line of sight and the signal is prone to being blocked by high ground or large structures.

VHF weather broadcasts are normally of inshore waters forecasts but may also include some forecasts for open sea areas.

Broadcasts are usually in the local language although some countries, such as Spain, Croatia, Greece, Italy in my sailing experience, do have English language versions as well. With European Latin based languages, there is normally little problem in learning the basic terms. These can be found in the RYA weather forecast booklet, G5. For thos who worry about the language, I have a comprehensive list of French weather words on another page.

The UK Coastguard say that this long wave system is the main method for dissemination of weather and navigation information from the fairway buoy out to about 200 NM although it can often be received further out. The technology is old, late 1940s or 50s, I think. Speeds are slow being determined by teleprinter technology.. Stations broadcast, in turn, in 10-minute slots over a 4-hour cycle. Stations use a common international frequency of 518 kHz. Because of local interference and screening signals may not be received in harbour. Otherwise, there are reception problems for three main reasons. First, if one station overruns its allotted time and a vessel is within range of the next station, then the two signals will interfere with each other. Secondly, such interference can also occur when there is high pressure and a low level temperature inversion. The ground wave signal travels further than normal and two stations broadcasting at the same time, normally far enough away from each other, will cause interference. Thirdly, at night, depending upon the state of the

ionosphere, signals can bounce back down to earth and cause interference; see my NAVTEX problems page. This sky wave can cause interference with a much nearer station whose signal is being received by ground wave.

NAVTEX provides, as a minimum, twice a day, 24 hour forecasts with a brief outlook that should be for a further 24 hours. The areas covered are sea areas as used in the BBC shipping forecast. for example. The French term is "bulletins au large". Gale warnings and cancellations are also broadcast.

NAVTEX broadcasts on the 518 kHz frequency are always available in English and are always for open sea areas ie not inshore waters. The UK, exceptionally at present, uses a national NAVTEX frequency of 490 kHz for inshore waters forecasts.

This is, effectively, the open ocean version of NAVTEX. Transmissions are from geostationary satellites. This, in effect, limit reception to latitudes equator-wards of about 60 – 65 degrees. There are versions of the receiving equipment that are designed for non-SOLAS vessels eg Mini-C. Although rather expensive, INMARSAT-C can also be used to send (slowly) text messages and emails.

The weather information provided is a 24 hour forecast and a brief outlook for a further 24 – 36 hours. Areas covered are for the open ocean, eg the UK North Atlantic bulletin. The French term is "bulletins au grand large".

This is a HF/SSB (Single Side Band) long range radio system. RTTY is used by the German weather service, DWD and the US Coast Guard in their SITOR (Simplex Teletype over Radio). Again, the technology is old and speeds are slow – similar to the football scores that appear on TV. RTTY can be received using a HF radio with SSB capability plus a computer and some software. For the DWD service, there is also the NASA Weatherman which is, in fact, a HF/SSB radio pre-tuned to 4 of the six DWD frequencies. For more, see my Radio Teletype Page.

European and Mediterranean sailors make great use of wind forecasts at a small number of numerical weather prediction model grid points. These are available out to 5 days ahead. Around the coasts of Germany there are inshore waters forecasts. More generally, there are also forecasts for the first 24 hours. Around NW Europe, these are available for shipping forecast sea areas and are a useful backup to NAVTEX. For areas further afield, eg the

Mediterranean, these 24-hour forecasts are too general to be of much use. DWD schedules can be found from a link on my GMDSS page.

There are also broadcasts of weather reports from ships and land stations. These are in a numerical coded form but, with a little practice, can be interpreted. There is some clever software that will interpret the data and even draw a chart for you on your computer screen; this is an example analysed synoptiv chart. Be careful because the data are not quality controlled. The garbage in garbage out principle holds good.

SITOR has been called a long range form of NAVTEX. It is used by the USCG to broadcast navigation and weather information over the Atlantic and Pacific oceans. It is used over the polar regions which are not covered by INMARSAT-C.

This is another old system that uses HF/SSB to broadcast weather charts. Either a computer and software is needed or a dedicated receiver/decoder. Transmissions are very slow and it can take 20 minutes to receive a chart. There are moves to replace Radio Fax by a satellite based system which may or may not be sufficiently user friendly to attract leisure sailors. Radio fax schedules can be found from links on my GMDSS page.

Although it can be useful, and I have found it so, it has been largely superseded by alternative delivery systems and techniques. These include Internet web pages and the use of email and GRIB coded products.

Use of national radio very obviously depends upon ability to comprehend the language. The BBC shipping forecast is, arguably, one of the most useful simply because it is updated on a 6-hourly basis. Those sailing in the Northern North Sea and Southern Baltic have said that the German Public service radio broadcasts in German are exceptionally clear and easy to understand.

Local radio, in the UK at least, is a variable feast. Much depends on the interest of the local station controller and staff. Schedules and content can vary at no or short notice. Not to be relied upon.

For most of us this means a mobile, terrestrial system but it must be likely that satellite phones will become cheaper to buy and use in time. For terrestrial telephone systems, a serious limitation is distance from an aerial. These are likely to be placed to optimise use over land. Use over sea may not be possible even 5 miles out. Use at anchor will depend, again on aerial location and local topography. There are aerials that can extend range greatly. Also, using Bluetooth to connect phone to computer allows the phone to be put up to 10 m higher than the laptop computer. Using a mobile phone, access is possible to access the Internet for browsing or email using GSM. However, the lack of bandwidth can make this expensive. Most people these days use GPRS or a derivative. Speeds will be much faster than GSM and substantially faster than a dial-up land-line.

GPRS is particularly useful to access pages of text using the Saildocs web page text service and the GRIB code service both available at no charge via, for example, Saildocs. For many GMDSS forecasts there are fast downloads available, see my GMDSS page.

Until recently, costs of downloading data have been quite large, up to £10 per Mb of data but are coming down rapidly. During 2008, Orange were

providing 5 Mb a month for £12. This service could be turned on and off when required. Download speeds can be greatly increased using a data compression package such as Onspeed or MailASail. This reduces the size of downloads by a factor of around five times.

Chart downloads can be costly, even over GPRS, but all the latest available UK Met Office charts can be obtained from the UK Weather Org Site in a compressed format. Copy and paste individual thumbnails into Paint and then enlarging results in a little fuzzy, but quite usable, chart. The possible disadvantage is that you have to take all the charts out to 5 days ahead, a download of between 140 and 230 Kb depending on how many charts are available at the time..

Recently (Autumn, 2008) there have been number of firms offering 3G "dongles" that can download at broadband speeds. In Italy, data costs were £10 for 1 Gb a month and a yearly contract was not required. It is a moving scene and this page will be out of date when you read it.

For advice on setting up and using mobile phone and laptop to connect to the Internet, see the Mobile Phone set up page.

Each of the above has its own role and there is really very little duplication. VHF and NAVTEX should be regarded as necessary because these are the systems put in place under the GMDSS for the dissemination of MSI. If you are a blue water sailor, then INMARSAT-C is the NAVTEX equivalent. However some long distance sailors rely upon RTTY/SITOR. Perhaps what we need is a low cost, receive only INMARSAT-C terminal. For the time being Mini-C is the leisure sailor's option.

In a sense, of course, detailed weather forecasts on ocean crossings are not vital. If bad weather is coming there is little that the average cruising sailor can do. His yacht is too slow to be able to avoid major storm systems. All that is necessary is sufficient warning to prepare the boat and crew for the worst. This may seem like heresy, but it is a view put forward by blue water sailors, INMARSAT-C or the same forecasts over HF/SSB will give two days warning of severe weather.

For European/Mediterranean sailors the DWD RTTY is an extremely useful service, especially for those all important 5 day forecasts. This means HF/SSB and a computer or the NASA Weatherman. This is NOT a NAVTEX replacement, as so many seem to think.

A mobile phone system has much to offer and is a useful backup way of getting open sea area forecasts when NAVTEX has not been received. It does, also enable reception of INMARSAT-C texts by quick download from the http://weather.gmdss.org/gmdss.html site.

In some ways, a mobile phone is an obvious replacement for NAVTEX. However, it must be remembered that NAVTEX is an operational service, available on passage, providing weather and navigation warnings. Mobile phone reception is of limited range.

Internet services are not operational and there is no warnings system. There have been some well publicised examples of lives being saved at sea using a mobile phone. Nevertheless, the MCA strongly advises that they are an additional resource and not a replacement for conventional marine radio systems.

All the systems have their place in the scheme of things. There really are few "either/ors" Radiofax is the obvious one to forgo and, for coastal sailors, INMARSAT-C. Perhaps one could forgo the RTTY equipment and rely upon the US GRIB for outlook and planning purposes. I do find that it is reassuring to have and to use both. Contrast and compare! See also the links on these pages, in particular those on NAVTEX, Radio Teletype, VHF, and Sources of Forecasts,