OK Navigators, what are these for?

[GordMay]

... 'What about LORAN ?' I hear you ask....
Even after the war and the invention of LORAN I doubt they had it.... I never came across it on any British ship I sailed on... with one exception and she had been built for a Norwegian owner ...

This is a shortened version of the 1947 "LORAN for Ocean Navigation" filmstrip, produced by the Coast Guard, as a sales pitch to commercial shipping lines to adopt LORAN (as a both a navigational aid and to assist in distress situations).
➥ https://timeandnavigation.si.edu/mul...e-loran-system

The first LORAN (A) chain went live in June 1942 at Montauk and Fenwick. By the end of World War II there were 72 LORAN stations, with over 75,000 receivers in use.

[Uricanejack]

Originally Posted by El Pinguino

At last... I think we have a definitive answer..... from the Old Pharts site I frequent

'Folks,

Have been following this thread with interest?
As someone who spent 5 years as a navigating officer on Cunard cargo vessels from 1967 to 1971 have been pondering the question posed by Cisco.
Perhaps the plus/minus refers to "twist"?
When I first joined Cunard it was the time that the Queens were being disposed of as well as many navigators. Some transfered to the cargo fleet. I was advised by these experienced gentlemen that to counteract the gulf-stream they applied a "twist" allowance of up to +/- 2 degrees to N. Atlantic GC courses. Strangely it worked on the many crossings I made during those years as navigator and our landfalls were generally spot-on.
Hope you all have a prosperous and healthy New Year. Cheers, Chris'

Interesting
Never heard the term. Must have been company jargon, for set and drift.Those guys would be doing the Atlantic day in day out.
Prediction of set and drift based on previous experience would be logical and putting on the board for all to see good practice.
I never did. I never did 30 knots across the Atlantic.
Often applied set for an anticipated current based on local knowledge. A Cunarder would have mutch better local knowledge of the Atlantic than I ever did. Southampton to New York anyway,

[Uricanejack]

Originally Posted by El Pinguino

And also ... regarding 'twist'...

QM and QE would both have been doing 700 mile 'days runs'.... thats a long time between 'sights' ( even when you divvy it up between morning stars/noon/evening stars and don't allow for overcast conditions...) so they would have been running on DR for considerable distances.

'What about LORAN ?' I hear you ask....
Even after the war and the invention of LORAN I doubt they had it.... I never came across it on any British ship I sailed on... with one exception and she had been built for a Norwegian owner.


Another handy little factoid for you .... one of the largest British companies - Blue Star Line - owned by Vesteys the Butchers - only started fitting radar to their ships in the late 1960s.... a very conservative animal was the British shipowner...

This is where I sought enlightenment https://www.shipsnostalgia.com/showthread.php?t=289523

Seems someone had the answer at #2 but then the thread wanders a bit..... until several days ago.

Never saw loran on a British ship or a 10 S band. Both American . I did use loran on and 10 cm S Band on an American owned ship. I am from the UK originally.
Even so I can see the British have a real “ not invented here” issue.
On the other hand the British do invent a lot of stuff. They just don’t like it when someone else makes a better version.

From memory it was ok of the US coast but the version we had required loran lattice on the charts US NOAA charts had the lattice our admiralty folio didn’t. It’s long range accuracy was questionable anyway. Although position accuracy was questionable the error was reasonably constant. Used both Deca and Loran coastal loran for US coast Deca for Uk NSea.

Typical tramp. We didn’t have anything until the law required it. Sailed with an Early ARPA and transit Sat Nav. Oldest rust bucket tramp tanker in the company. But chartered with a Cargoe for the US. They were flown out to Malta Fitted by Gibraltar, required box’s ticked. Never saw one again for years.

Until Kelvin Hughes made them for yachts. Rumours the boss got a free set for his boat with the deal. Deca is long gone. So is the Transite Satelite. GPS was after my time. I hear Loran is still going.

Loran was US system like sat nav publicly funded. Deca was a private company who rented the receivers, I sailed occasionally with mark 12 and 21 the lattice charts and interpolation. Company only put it on NSea based ships. until KH produced a set which gave lat long and was way better.

I did once sail with an Omega. A US system supposedly world wide. The military system may have been quite good. The one we had would just about confirm which ocean we were in.

Being Scottish it kind of bugs me. The New Queens were built in France. For an American owned company.

Which originally was Canadian.

[Don C L]

Originally Posted by El Pinguino

At last... I think we have a definitive answer..... from the Old Pharts site I frequent

'Folks,

Have been following this thread with interest?
As someone who spent 5 years as a navigating officer on Cunard cargo vessels from 1967 to 1971 have been pondering the question posed by Cisco.
Perhaps the plus/minus refers to "twist"?
When I first joined Cunard it was the time that the Queens were being disposed of as well as many navigators. Some transfered to the cargo fleet. I was advised by these experienced gentlemen that to counteract the gulf-stream they applied a "twist" allowance of up to +/- 2 degrees to N. Atlantic GC courses. Strangely it worked on the many crossings I made during those years as navigator and our landfalls were generally spot-on.
Hope you all have a prosperous and healthy New Year. Cheers, Chris'

Amazing, thanks for that Pinguino!
Thanks to all for the enlightening contributions here

[Lodesman]

Originally Posted by Uricanejack

I did once sail with an Omega. A US system supposedly world wide. The military system may have been quite good. The one we had would just about confirm which ocean we were in.

Omega was world-wide, and IME was paired with Transat - the two systems complemented each other. The sat-nav was accurate, but it could go 6-12 hours between fixes. The Omega was constant, but not particularly accurate. The sat fix would give two possible locations on the earth, so Omega was used to resolve the ambiguity - the highly accurate sat-fix then gave a correction to the Omega position, which was then applied as an EP of sorts, until the next sat-fix. Omega was a hyperbolic system like decca/loran, but used phase-comparison rather than time difference - only needed 8 transmitters, stationed around the world. Very clever system - but I believe the Yanks ripped-off the idea from the Brits.