Gps

[Keith Tindell]

I wonder how things would go now if GPS systems were switched off ?, i would think that many of the old ways would be forgotten. My navigation knowledge is only in small boats, and mainly coastal, but the old RDF sytem is still useful for Aero beacons , and harbour entrance signals. One wonders if these skills are still used by big ship navigators?. Morse code was removed from the RYA sylabus some 20 years ago. The other system (the name of which i have forgotten now) in the approaches to the Isle of Wight, consisted of a transmitter buoy in Scratchels bay, and another off Start point, where you listened on the VHF (channel number forgotten), and it transmitted a system of beats in groups of ten, when the beep faded, that was your bearing from the transmitter. Have used that system in poor viz on many occasions, this system has now been switched off. KT

[j.sabourn]

Maybe should hope they are never not useable, as will be at war more than likely. For those that did the MN Defense course in the early 60"s when things were getting tense between Russia and the USA. The first attack on the UK and was estimated that two thirds of the country would be wiped out, all radio communications would cease, no ports to discharge or load at. That was just over 50 years ago. Doesnt bear thinking of the present weapons available. All such weapons of mass destruction should be banned, any country who starts using , are promoting the end of mankind. JS

[happy daze john in oz]

Maybe should hope they are never not useable, as will be at war more than likely. For those that did the MN Defense course in the early 60"s when things were getting tense between Russia and the USA. The first attack on the UK and was estimated that two thirds of the country would be wiped out, all radio communications would cease, no ports to discharge or load at. That was just over 50 years ago. Doesnt bear thinking of the present weapons available. All such weapons of mass destruction should be banned, any country who starts using , are promoting the end of mankind. JS

John, sadly I have to tell you but thta is how it will end. Some lunatic in a country such as North K will one day think he is a supreme being and let one go. The west will retaliate followed by Russia then china and it will be good night nurse for all of us.

[John Arton]

Radio Direction Finders are no longer a requirement to be fitted on ships provided that alternative position fixing devices such as GPS are carried. If no RDF is fitted then an exemption certificate is issued and included in Part B of the ships safety equipment certificate.
After the demise of the Decca Navigation system, widely used by especially fishermen who would use one of the coloured lines on a Decca chart as a reference to good fishing grounds, the only long range electronic navigation system left is LORAN, the American equivalent to Decca. Decca only had a range of around 200 miles whereas Loran had ranges of over 1000 miles. Decca was killed off by the bandwidth that it used being required for the mobile phone industry.
GPS for pilotage is not so good so there is differential GPS which uses land based radio transmission's to correct the GPS signal to give an accuracy down to plus/minus centimetres. This system is often used by pilots who carry there own laptops with highly accurate and up to date charts with the very latest real time depth contours on them in a number of ports world wide. All AIS system's have a Pilot port fitted for Pilots laptops to be plugged into in order that they can utilise the ships GPS signals. There are also in a number of ports using mobile phone technology coupled with GPS to give them highly accurate navigational data which on the huge ships of today with their deep draughts and limited channel space available is an absolute necessity when entering crowded ports.
The maritime industry is only now waking up to the fact that GPS can be easily high jacked and that all the computer based systems on board are very vulnerable to computer hacking. There was an experiment carried out where a mega yachts integrated navigation system was high jacked from a remote computer and the yachts course altered by over 90 degrees without any on board realising that they were 0 degrees off course as all their instruments were still showing that they were heading on their intended heading.
There is a move afoot to make the fitting of Loran C a requirement as a back up to GPS and money is being put into developing the Loran C system to make it more stable and accurate as well as easier to use.
With the advent of digital signalling the amount of bandwidth allocated to the maritime sector is gradually been reduced with even the bandwidth of radar being reduced.
Although we may all think that since the demise of the radio operator and morse code etc. using HF and MF radio signals that radio signalling is a thing of the past, in fact in todays world it is ever more present as everything from your mobile phone to your television set uses radio signals in one form or another and there is a limited amount of useable radio bandwidth that enables good signal quality for communications. The discovery of digital signalling has allowed much faster and greater quantity of information to be passed over similar radio bands and the allocation of radio bands is constantly under review by the International body that governs the allocation of all radio bandwidths.
I am no expert on this subject, just an observer and ex. user so my description may be on the "idiots guide" to GPS and radio transmissions, so I hope I am not leading anyone astray in my observations and use of terminology.
rgds
JA

[Keith Tindell]

Thank you for that description John, i had often wondered how much of the old systems remained. As i have said before, i do not claim to be an experienced navigator, only in small mainly sailing vessels, but i wonder on a weekend at the needles lighthouse, how many sailing and power boats set a course by GPS for Cherboug and set off, many i would suspect do not even have a chart out on the table, and in the middle of the sailing season its like all travelling down the M1. if Gps were to go down i can imagine the confusion. My own experience of Decca was how unreliable it was especially at night, and so was constantly cross referencing with RDF and log reading, tidal drift etc etc, . Strangely it was the part i enjoyed most KT

[Ivan Cloherty]

. My own experience of Decca was how unreliable it was especially at night, and so was constantly cross referencing with RDF and log reading, tidal drift etc etc, . Strangely it was the part i enjoyed most KT

It's what we did Keith, it was a challenge, especially on the coast, and that's why we enjoyed it, found the Decca an absolute godsend on ships without radar and fairly accurate for its day, with its red, green and purple clocks in the console and coloured lines on the charts, certainly missed it when joining ships without it. Remember coming from deep sea and joining a coaster with it, thought I was in heaven.

[john sutton]

The only electronic navigation aid I saw in my days at sea was decca.This was on the Somme a coaster and consisted of a box with three dials and lights coloured red,green and blue if the reading was taken from the box and taken to the charts which had red green and blue lines which were numbered you could get an accurate position.I only ever saw this on the one vessel and was obviously only any use rond the coast.
Years after leaving the sea I used decca on various boats I owned and even navigated down to spain on decca although we lost it in the middle of the bay and worked of dead reckoning until we picked it up again off the Spanish coast.

[j.sabourn]

I was just going to say that John you used to lose the Decca Chains shortly after entering the Bay, going down to Gib when working for Naval Party 1007 used to take a couple of runninng fixes with the sun. A naval Lt. who was on board one trip asked if he could come up and do a morning sight , on coming on the bridge he wanted a naval printed out form which suppose told him what to do, told him we didnt carry, so he diddled of, think told the story before. The Navy in a number of ways and manners were not brought up and trained the same as the MN, however technically I suppose they were further advanced than us re communications. Think it was mentioned before every merchant ship that went down to the Falklands had its own naval communicators on board. JS

[John Arton]

John S
Falklands, yes all the MN ships that went down had naval radio officers with there own gear on board.
Keith
Used the Needles channel often when leaving Fawley and the yachties were a nightmare especially the power boat men. I have had many a scare with very expensive power boats racing across the entrance without a care in the world and totally ignoring the presence of any other shipping, be it commercial or leisure, that was in the same vicinity.
Came out once when the Vendee round the world race yachts were coming into the finish and that was a real nightmare, huge sailing yachts intent on still racing even coming in through the needles and there we were fully lading trying to give them sea room going down the channel, tried to call them to give them warning that I was running out of water but not one of them replied despite them being constantly on the VHF to the port and race organisers.
Still strangely enough, despite having to put up with the fools on yachts, always enjoyed our trips in and out of Fawley.
rgds
JA

[Ivan Cloherty]

The only electronic navigation aid I saw in my days at sea was decca.This was on the Somme a coaster and consisted of a box with three dials and lights coloured red,green and blue if the reading was taken from the box and taken to the charts which had red green and blue lines which were numbered you could get an accurate position.I only ever saw this on the one vessel and was obviously only any use rond the coast.
Years after leaving the sea I used decca on various boats I owned and even navigated down to spain on decca although we lost it in the middle of the bay and worked of dead reckoning until we picked it up again off the Spanish coast.

Stand to be corrected John, but sure that they were red, green and purple, because they were starting to introduce the sea as blue on the charts then, so would have been hard to find the blue lines on a blue chart especially at night under subdued light, not that its important, just testing my memory Cheers