John Leary
23rd August 2006, 20:58
I had the good fortune to visit a game reserve in Ceylon (now Sri Lanka) back in the early-sixties and was lucky enough to see a wild leopard after much pointing and whispering by our game warden guide who spotted this well camouflaged animal without the aid of binoculars, way into the distance whilst it was lying down resting at the base of some bushes. Not much to do with this story but I have included it to make the point that we develop our senses differently and whilst as an R/O at sea I could read very weak signals through severe interference I never acquired the ability of the navigating officers to identify small objects or coastline features at what I thought were impossible distances.
The Marconi Lodestone direction-finding (DF) equipment was a great piece of equipment. The DF receivers on the Brocklebank ships I sailed on were installed in the radio room and the bearings taken by the R/O. The ones I used only provided relative bearings. Later equipments like the Marconi Lodestar which were capable of providing automatic bearing measurements were I believe installed in chartrooms.
I used the Lodestones many times during my sea going career to confirm where we were when the weather was bad around the coast and when we were outside of the range of the ships radar. They also had to be checked and calibrated at regular intervals in order to keep the ships wireless license up to date.
This anecdote relates to the time in 1966 when the DF was used so that we could arrive at Jeddah in the Red Sea at night in order to save time.
The navigating fraternity familiar with the port of Jeddah will know that the waters on the approach to the port can be treacherous. It’s probably still true but in the 1960’s the route into Jeddah was marked with the wrecks of ships that hadn’t made it.
For reasons that I cannot remember now, the Master of the Manaar decided that he had to make his arrival at night and could not afford to delay arrival until daylight hours.
He decided to sail down the Red Sea parallel with the coast but in safe waters and at the appropriate time turn through 90 degrees and sail in. I have probably oversimplified the operation and if so I hope that any navigators reading this will forgive me.
The exact point along the coast when the ship made its turn was to be judged with the help of the ships DF equipment, taking radio bearings on an aeronautical beacon located at Jeddah’s airport which was behind the port. The beacon was recorded as reliable for maritime navigation and had a range of 150 miles.
I was told that as we moved much closer to Jeddah having made the turn, the position of the ship could be checked with visual bearings taken on the light fitted at the top of the beacon’s mast. All I had to do was to take radio bearing on the beacon to assist in deciding when to turn.
It was usual practice when using the DF to set the ships aerials into a predefined standard arrangement so that the same electromagnetic conditions would apply around the DF loops. It was also practice to lower any private broadcast receiving aerials that might be erected close to the loops that could affect the accuracy of the bearings.
I was confident about the accuracy of the DF equipment on Manaar that voyage as we had taken check bearings on a radio beacon when coasting around the UK before sailing deep sea. This however was the first and as it turned out the only time that I ever took bearings from an aeronautical beacon. I remember that I started to take the bearings after the last of the normal radio watch keeping periods of the day. I cannot remember exactly when but I suppose I commenced taking bearings when the beacon was midway between the bow and beam on the port side.
The radio bearings were provided to the bridge every six minutes. It helped that the beacon transmitted its long dash and identity signal continuously. Having taken the bearing and nulled the received signal with the sense aerial all that was then required was to apply the correction factor (for quadrantal and semi-circular errors) to the measured bearing. Fading of the beacon’s signal that would have indicated other types of error was not experienced at any time.
As the bearings approached the turning point I believe that the ship reduced speed so as not to overshoot. On 270 degrees relative, the ship turned 90 degrees to port so that the beacon was then dead ahead. Manaar then steamed towards Jeddah with the navigational staff keeping visual and radar lookout. I imagine the echo sounding equipment was also working overtime. I continued to monitor the beacon on the DF but I cannot remember if any further bearings were requested after we turned.
After what seemed an age I was told by the bridge that it was possible to see the loom of the beacons light and that visual bearings were then possible. A little later I was informed that radio bearings were no longer required and I could stand down.
With some relief I went on deck to look forward but although I knew that the light was dead ahead I could not see what the navigating officers clearly saw. I was told that the loom was the glow around but not the direct light emitted by the beacon.
Having confirmed that I was no longer required I gratefully turned in. Although the Manaar made a successful passage to Jeddah, I never did see the light.
The Marconi Lodestone direction-finding (DF) equipment was a great piece of equipment. The DF receivers on the Brocklebank ships I sailed on were installed in the radio room and the bearings taken by the R/O. The ones I used only provided relative bearings. Later equipments like the Marconi Lodestar which were capable of providing automatic bearing measurements were I believe installed in chartrooms.
I used the Lodestones many times during my sea going career to confirm where we were when the weather was bad around the coast and when we were outside of the range of the ships radar. They also had to be checked and calibrated at regular intervals in order to keep the ships wireless license up to date.
This anecdote relates to the time in 1966 when the DF was used so that we could arrive at Jeddah in the Red Sea at night in order to save time.
The navigating fraternity familiar with the port of Jeddah will know that the waters on the approach to the port can be treacherous. It’s probably still true but in the 1960’s the route into Jeddah was marked with the wrecks of ships that hadn’t made it.
For reasons that I cannot remember now, the Master of the Manaar decided that he had to make his arrival at night and could not afford to delay arrival until daylight hours.
He decided to sail down the Red Sea parallel with the coast but in safe waters and at the appropriate time turn through 90 degrees and sail in. I have probably oversimplified the operation and if so I hope that any navigators reading this will forgive me.
The exact point along the coast when the ship made its turn was to be judged with the help of the ships DF equipment, taking radio bearings on an aeronautical beacon located at Jeddah’s airport which was behind the port. The beacon was recorded as reliable for maritime navigation and had a range of 150 miles.
I was told that as we moved much closer to Jeddah having made the turn, the position of the ship could be checked with visual bearings taken on the light fitted at the top of the beacon’s mast. All I had to do was to take radio bearing on the beacon to assist in deciding when to turn.
It was usual practice when using the DF to set the ships aerials into a predefined standard arrangement so that the same electromagnetic conditions would apply around the DF loops. It was also practice to lower any private broadcast receiving aerials that might be erected close to the loops that could affect the accuracy of the bearings.
I was confident about the accuracy of the DF equipment on Manaar that voyage as we had taken check bearings on a radio beacon when coasting around the UK before sailing deep sea. This however was the first and as it turned out the only time that I ever took bearings from an aeronautical beacon. I remember that I started to take the bearings after the last of the normal radio watch keeping periods of the day. I cannot remember exactly when but I suppose I commenced taking bearings when the beacon was midway between the bow and beam on the port side.
The radio bearings were provided to the bridge every six minutes. It helped that the beacon transmitted its long dash and identity signal continuously. Having taken the bearing and nulled the received signal with the sense aerial all that was then required was to apply the correction factor (for quadrantal and semi-circular errors) to the measured bearing. Fading of the beacon’s signal that would have indicated other types of error was not experienced at any time.
As the bearings approached the turning point I believe that the ship reduced speed so as not to overshoot. On 270 degrees relative, the ship turned 90 degrees to port so that the beacon was then dead ahead. Manaar then steamed towards Jeddah with the navigational staff keeping visual and radar lookout. I imagine the echo sounding equipment was also working overtime. I continued to monitor the beacon on the DF but I cannot remember if any further bearings were requested after we turned.
After what seemed an age I was told by the bridge that it was possible to see the loom of the beacons light and that visual bearings were then possible. A little later I was informed that radio bearings were no longer required and I could stand down.
With some relief I went on deck to look forward but although I knew that the light was dead ahead I could not see what the navigating officers clearly saw. I was told that the loom was the glow around but not the direct light emitted by the beacon.
Having confirmed that I was no longer required I gratefully turned in. Although the Manaar made a successful passage to Jeddah, I never did see the light.