Navtex woes

[chrisrixon]

I´m currently in Gijon, N Spain. Lots of boats are complaining of poor Navtex performance. Anyone know whats going on?

I am getting 0000 forcasts from Corsen (brittany) but the 1200 forcasts are high error eg 26%

I am getting nav warnings from La Coruna clear as a whistle but no forcasts.

Its a real pain ....

More info: My set is a Furuno and the ariel has stainless stell from the pullpit around it, is that bad?

Also do these stations not repeat the weather every 6 hours? My feeling is that it is only transmit when fresh and not repeated 6 hours later.

It´ll be back to Radio 4 at this rate

Cheers Chris.

 

[ParaHandy]

Chris

Corsen (A) 518khz transmit weather at 0000 & 1200 utc. I have found a significant reduction in signal strength at midday and if inside a busy harbour or ferry port, even worse. Weather forecast is only, normally, at these times.

Coruna (D) 518khz 0030 & 1230 utc. ditto above.

Have snipped this off Frank Singleton's Navtex site:

Douglas

After discussing my NAVTEX with others, much more knowledgeable on radio reception, I looked at the earthing for my set. At installation I had connected the negative to the ground used for many of the yacht's electrics. This turned out to be a keel bolt. To get a better earth, I bared some of the aerial wire and connected the screen of the coaxial cable to the sacrificial anode.. The result was instant success! CORSEN was received, somewhat patchily, in St Jean de Luc almost down to the Spanish border. Likewise NITON. Interestingly, but of no relevance to our needs, we also received stations from afar, notably Reykjavik in Iceland, when night time signals bounced off the ionosphere.
Still, we did not think that reception was as good as it might be although the north coast of Spain is over 300 miles from le Stiff and over 400 miles from NITON. At Santander, another yacht had the same NASA NAVTEX Pro and the same manufacturer's whip aerial only marginally higher than ours. They were getting much better reception. Perhaps my aerial was too near the Aerogen pole after all.

We then moved the aerial to the other quarter and, after that, got generally acceptable results. Even in harbours as far south as St Dennis d'Oleron we were able to receive messages although with some garbling. Coming up the coast of France reception improved steadily from both NITON and CORSEN. Interestingly and surprisingly, until we got as far north as South Brittany we found that NITON was often received more completely than CORSEN even though NITON was further away and the signal was coming over land.. On return to the Dart we found good reception there of both NITON and CORSEN. From Chris Pink, UKHO, we later heard that CORSEN had been having problems that year.

On our 2000 cruise to Barcelona from the Dart we found good reception from la Coruña, once he came back on the air, as far south as Peniche. Lisboa (Monsanto) was received from about Peniche round as far as Cape St Vincent but I lost him in Lagos. We received Tarifa from somewhere east of Faro until near Cartagena. After that we received Valencia (Cabo la Nao). As far north as Barcelona, Valencia was getting erratic. We could not receive in Barcelona harbour.

I still thought that my reception was not so good as it might but could not decide whether this was due to the budget price set or the aerial. I thought the latter. In fact, I strongly suspected that most reported NAVTEX problems are due to poor aerial siting, poor earthing or people simply trying to receive in poor locations. The latter can be in marinas surrounded by masts, in among buildings especially with electric equipment or in areas with a great deal of screening.

For our 2001 season in the Med I installed a new NASA active aerial. This is a short stub, similar to my rather old GPS aerial in appearance. The results have been excellent. My suspicions were amply confirmed. For example, we were receiving Toulon down the east side of Sardinia. In 2002, in Tarragona marina, we were receiving both Toulon as well as Valentia.

Any yachtsman not getting good NAVTEX reception should inspect his on board installation carefully and experiment as we have done. The results are well worth the effort. It must be remembered that NAVTEX signals are only ¼ kW at night and 1 kW by day. Hoping to receive under the shelter of land, a long way from a transmitter is unlikely to be successful. The proximity of other sources of radio emissions is also likely to affect, adversely, NAVTEX reception.