"Location, location, location" Topic

So back in the day of sailing ships, position could be determined by use of chronometer and sextant. How was it done during WWII?

Pretty much the same way

Weren't there radio location methods too?

Some wrecks are found considerable distances from the reported action location.

The early model B-52 bombers had a window in the top so the navigator could shoot the stars with a sextant. By that time, it had become a backup plan, used to confirm the radio navigation.

Grelber

Latitude could be determined from the earliest days of the Age of Sail by use of the sextant ("shooting the sun"). Accurate determination of Longitude was really not possible until the invention of chronometers able to keep very accurate time over extended periods at sea. It was a great technical challenge and the Admiralty ultimately paid an extremely handsome award to the inventor of the marine chronometer (1790's IIRC). See the book "Longitude" by Sobel -

link

With the advent of long-range radio direction-finding, a ship could get a fix on its position by triangulation of signals from powerful shore stations. But the accuracy of any given directional azimuth depended upon a variety of factors – strength of transmitted signal, distance of shore station, atmospherics, efficiency of ship's receiving apparatus. The more shore station azimuths taken (and the angles formed by them relative to one another) the more accurate the estimated fix would likely be. At the end of the day, you would would far more likely end up with a zone or area of positional confidence rather than an exact cross-reference position.

A friend of mine who spent many years in the merchant marine once told me that, if bad overcast hid the transit of the sun for a period of days, they would be lucky to achieve a positional fix any closer than +/- 100 miles of their true position in the open ocean. This was, of course, in pre-satellite days. Hence, sighting of a land-based navigational landmark (lighthouse or unique geographical feature, for example) was always important in order to confirm one's true position as compared to one's estimated position.

FWIW.

B

British tankers were using sextants in the Western Desert--and out in that same desert was the Lady Be Good, which missed its airfield and kept right on going because the RDF people "read the back of the loop" and were 180 degrees off.

Shall I mention a crew on extended night land navigation at Fort Benning in 1984 which wound up in Alabama? I still don't know how they pulled that off: you had to traverse a river to do it where they did.

During World War 2, the UK and the US developed the LORAN A (Long Range Aid to Navigation) system. It allowed precise location measurement across vast distances. By the end of WW2, over 75 Loran A stations were in operation in the PAcific, and several more in the Atlantic.

Ho pzivh43,

My Dad (WW2 USN coxswain on a PTO Tin Can) had a Loran system on his 41ft Bruno Stillman offshore sport fishing boat (along with a PPI radar set-up and three radios – safety first) which he ran out of Boston MA. I do not know what Loran version he used – A or C. I can remember being on buoy spotting duty in the bow on one or two occasions when he had to feel his way back into Boston harbor through heavy fog by radar – definitely a pulse quickener.

I looked into the wartime history of Loran A (google "Loran A" – there is great Loran veterans' historical website still on line). A fairly long time (about 2 years) was taken up by technical development (MIT RadLab and NDRC). Large scale operational deployment did not seem to have gotten under way until 1944 or so (with about +/- 1pct range accuracy).

FWIW.

B

RAF C-130 Hercules in the 1980s had a number of different nav systems including the sextant and LORAN-C.

The simulators had them both.

I remember there were maps with lots of ellipses drawn on them for the Loran. The simulated Loran also had to produce a ghosting signal.

B