NAVTEX

[Danny_Labrador]

There’s an interesting article in Sailing Today this month that shows how you can connect an standard short-wave band radio to you laptop (earplug socket to sound card), and then with cheap/free software receive weather fax reports – I never knew that!

The article also mentions that the software has options for NAVTEX and other text base weather reports receiving but it does not make it clear if this can be done with a basic £60 radio.

Bit thick on this, can anyone enlarge the picture for me? It seems to be a good way of getting NAVTEX without the need for a dedicated receiver ?

[Benbow]

Yes there are several programmes that will do this for you. I use SeaTTY.

But there is a huge disadvantage vs a dedicated little box - you need to keep a PC connected to your radio waiting for the transmission and consuming power. Unless you also want Wx fax and TTY, I would get a dedicated device.

[EdBeynon]

The results will depend on the quality and stability of your radio. I've done it with a Sony ICF-SW-100 but they aren't cheap. You will need to be able to tune to side band for weatherfax. If you have the radio already then download SeaTTY and give it a try. Google 'Navtex Frequencies' to find out what to tune to for Navtex or use this link to get weatherfax frequencies and schedules.

[Gin]

I have a Sangean ATS909 which I bought for this purpose and have since been struggling with to pull in GRIB files, which everyone says is easy - so I must be a dunce!

I anticipate spending a lot longer at it over winter before I've cracked it [img]/forums/images/graemlins/confused.gif[/img] [img]/forums/images/graemlins/confused.gif[/img]

[beneteau_305_553]

Before getting navtex have a look at this site:

http://www.frisnit.com/cgi-bin/navtex/view.cgi

Navtex seems poor with regard to weather forcasts. The shipping forcast is often transmitted only once in 24 hours and you don't know when they are going to transmit it. I don't think the inshore forecast is transmitted at all.

A really good aerial is needed to receive the signal and even then difficult in marinas unless you are next to the Niton or Ostend transmitter.

Getting the messages via a wap message on a mobile seems better if you are within range and coastal sail.

More detailed weather forcast and nav warnings are transmitted on VHF and these are for your area.

receiving synoptic charts using weatherfax via radio is very good thanks to the royal navy Northwood but its not a written forecast.

[Danny_Labrador]

OK, I know what GRIB files are but how and from where do you download them and what software do you need ?

[Oldhand]

Depends what you call a "standard" short wave band radio. For a start the majority of Navtex is transmitted at the bottom end of the MF band (490kHz and 512kHz), which is hardly "short wave band". There is a third Navtex frequency which is short wave at 4209.5kHz but I have yet to receive a strong enough signal to decode from any source. In addition, the "standard" radio must be a Single Sideband (SSB) receiver, capable of upper sideband reception, a facility most domestic short wave receivers don't have. Although I haven't read the Sailing Today article you mention, it sounds misleading.

You also need to be aware that reception of the 2 MF Navtex frequencies can be degraded to a very high degree by interference from other onboard electrical/electronic devices. As a result, expecting a portable receiver with a telescopic whip antenna to provide good Navtex reception while stuck on the chart table is pushing your luck. Successful Navtex reception of more distant stations is very dependent on antenna siting and installation. Many people complain of poor Navtex reception relaibility in marinas. Having a Navtex antenna mounted at the masthead mostly overcomes this but I still sometimes get interference from neighbouring boats.

As already mentioned, if you do have a suitable receiver, its not very practical to run a PC on onboard for the sort of durations required for Navtex reception, unless you are prepared to power up the system at the published transmission times. However, not having a Navtex receiver with a printer, I do use PC Navtex reception for storing navigation warnings which are relevant to my sailing area, having already read them on my dedicated Navtex receiver display.