NavList:

Hi Folks

Always a good read – all your posts – was sitting in my daughter’s house whilst my wife and her were ‘shopping’- dangerous.

I turned on Prime and sifted through the junk – and up popped ‘Amelia’ – Richard Gere and another person – junk story on what happened to Amelia – I switched it off and went back to my kindle

I am reading a really good read that may interest you sailors out there “The Wager” = by David Grann – HMS Wager around 1740 – when navigation was an art not a science and though latitude was easy to get – longitude WAS NOT. The Longitude Act had been passed but no one yet had claimed the prize – John Harrison precision clocks didn’t become available until after the Wager. I haven’t finished the book but it is spell-binding intrigue.

Dead reckoning was the means of determining longitude – but without a decent compass, ships speed determination and a lot of other modern speed/drift and other basic navigational aids – throwing a dice and putting a pin in a map probably was just as good.

However, I have just finished an incredible book called “Mosquito” – by Rowland White – probably the most successful aircraft and the most diversly tasked aircraft of WWII ( my dad flew them in Bomber Command) – and NZ has just rebuilt from scratch a Mossie and it has just flown!.

I digress – but the story of the book the Mosquito was pivoted around the successful bombing of the Gestapo HQ in Copenhagen in 1945 by the low flying Mossie force – to get from England to the coast of Denmark the had to fly at 300 mph – at an altitude of 50 feet ( yep – salt spray covered their windscreens) - and their ONLY means of navigation was DR by a master Navigator ( one of the most successful RAF navigators of WWII) – Ted Sismore ( see Amazon ‘Gestapo Hunter’ – release date 1 Nov 24 – it can be pre-ordered). Anyways – for 1.5 hours – travelling at approx. 5 miles a min they DR navigated – the weather was awful ( to say the least) strong winds were from the North straight out of the North Sea – he hit the coast of Denmark almost bang on target!

(for the record – I am also a retired RNZAF Navigator and have knowledge and experience at DR Navigation – actually before GPS – our last flights (before graduating in 1975) were in a Strikemaster Jet at 50 ft – cross country – similar type speed and DR navigation was the only way of navigating – but we were over land and used land marks, rivers, railway lines, powerlines, towns to quickly pin point progress and adjust heading and speed to achieve time on target. This was very different to what was achieved by Sismore).

The Wager founded on the West Coast of what is now Chile trying to navigate East to West through the Horn – and their DR navigation was a long way in error 60 NM plus further East than reality – so when they needed to try and head up into the Atlantic away from the Horn they were just off the coast of Chile – and without any masts and strong westerly winds from the roaring 50s they were doomed. However, the author makes a note – a supposition I suppose from the logs of Wager crew – that ‘they estimated their position by Dead Reckoning and the stars ( there is actually an entire chapter called “Dead Reckoning” ) as such and such position” – I didn’t get out a map and plot it – but my question is to you sea farers…..

From what information could such information be gleamed – no accurate time piece. The maps of those days were not accurate – it was overcast most of the time...

So – if you were stranded somewhere down on the Tierra del Fuego archipelago western shore with basic gear, could you estimate your position?

I am very interested in the answer having never sailed before and my knowledge of navigation and DR is all via flying.

Regards Howard G