Will any useful lessons be learned from the loss of ‘Cheeky Rafiki’? Only if the hull is recovered and inspected.

The loss ‘Cheeky Rafiki’s’ crew in mid-Atlantic is a sharp reminder that sailing small boats across wide oceans can still sometimes be risky.

Photos of the upturned hull from which the fin keel had clearly been torn http://www.theguardian.com/world/2014/may/23/us-hull-missing-yacht-search-cheeki-rafiki have led many experts to wonder whether the boat was strongly enough built to withstand the stresses of a mid-Atlantic gale.

Radio reports from the crew about leaks suggest that the keel-bolts may have been working loose before the keel broke off.  Losing your keel in these circumstances would undoubtedly result in a terrifyingly rapid capsize and, with no chance to launch the liferaft, the crew would then have had very little hope of survival.

But before we rush to judgement we need facts.  If any useful lessons are to be learned from this disaster it is essential that experts be given the chance to examine the hull of ‘Cheeky Rafiki’.  And that will only be possible if the wreck is recovered and brought ashore for proper inspection.

I hope very much that this is in hand.  The easy option, of course, would be simply to sink the wreck, or worse still, abandon it.  That would be a great shame and terrible lost opportunity.

Frank Worsley’s difficulties…on NavList

I’ve just spotted an interesting post from Brad Morris on the fascinating website NavList – which is devoted to celestial navigation: http://www.fer3.com/arc/

It’s all about the difficulties facing Frank Worsley in rating his chronometer before departing Elephant island with Shackleton. This was a crucial operation if he was to have any hope of determining the longitude of the James Caird accurately as they crossed the Southern Ocean heading for South Georgia.  

As I recount in Sextant, Worsley had to take a sun sight for this purpose and – thanks to foul weather – only just managed to do so before they set off.  But for this method to work reliably it was essential to know the exact position of the place where he was making the observation.  

Brad Morris says that there was in fact a good deal of uncertainty in 1916 about the exact position of Elephant Island.  Not very surprising, given its remote location, but Worsley’s own account doesn’t mention this – perhaps he was unaware of it? http://fer3.com/arc/m2.aspx/Frank-Worsleys-Sextant-certificate-Morris-may-2014-g27804

A new alternative to GPS? The quantum accelerometer.

A new alternative to GPS? The quantum accelerometer.

Fascinating article in New Scientist about a possible ‘quantum positioning system’ soon to be tested in submarines.

GPS doesn’t work under water so submarines rely on fancy accelerometers to calculate where they have gone since their last accurate fix on the surface.  But this sophisticated form of ‘dead reckoning’ is still far from perfect.  After a day the ‘drift’ may exceed one kilometre.

The UK Defence Science and Technology Lab (DSTL) is now developing an enhanced acceleromter relying on the perturbations in clouds of atoms trapped and super-cooled by lasers.   If this can be made to work it may yield positions 1000-times more accurate than conventional accelerometers.

There are plans to test such a system at sea in 2016.  But one factor that will need to be taken into account is the gravitational anomalies caused by undersea mountains.  So improved maps of gravitational variations will be needed.

 

 

 

The new Longitude Prize

The new Longitude Prize announced yesterday is exciting but it’s a real shame that some of the coverage implies that Harrison was the ‘sole’ discoverer of the solution to the original problem back in the 1750s.  See http://www.telegraph.co.uk/science/science-news/10841125/Calling-all-geniuses-for-the-new-Longitude-Prize.html

The truth is quite different of course, as I’ve documented in some detail in ‘Sextant’. While Harrison’s prototype ‘H4’ watch was indeed a brilliant success, and paved the way for even better chronometers made by other craftsmen, the astronomers simultaneously achieved an extraordinary breakthrough with the ‘lunar distance’ method of determining the time.  Much of the credit was due to Tobias Mayer’s new tables predicting the moon’s complex motions.

In reality, the chronometer method and the lunar distance method of finding the longitude were to be used in tandem for many years to come, as is readily apparent from the logs of all the great navigators of the age, right through until the 1830s.  And both methods, of course, depended on observations made with a sextant!

‘Catastrophic failure’ of Russian satnav network causes alarm

newsphoto_glonass_logo

On 2 April the Russian satnav network, known as GLONASS, suffered ‘major disruption’ when all 24 satellites produced corrupted information for almost 12 hours.  It took almost 13 hours to fix and during that time GLONASS was giving location data up to 55 kilometers out off the UK coast, according to the General Lighthouse Authorities.  Pretty scary if you were relying on it!

This ‘outage’ is discussed in a fascinating new issue of Navigation News (from the Royal Institute of Navigation www.rin.org.uk). It starkly reminds us of the urgent need for a robust back-up to existing global satellite navigation systems (GNSS), including GPS.

It’s not yet clear exactly what went wrong with GLONASS but there’s no reason to suppose that GPS or any of the other GNSS now in the pipeline – including the EU’s Galileo – is any less vulnerable.

Professor Chris Rizos of the University of New South Wales commented: ‘This catastrophic failure of one of the world’s two global satellite navigation constellations is a wake-up call for all of us.  We ignore the possibility of these events at our own peril’.

It would be nice to think that the good old sextant might fill the gap but of course GNSS does far more than just give a positional fix.  It also provides a super-accurate time signature on which many non-navigational systems now rely – including the world’s financial markets and mobile phone networks.  So there’s a great deal more at stake here than shipwreck or taking a wrong turning.

The best potential back-up in the event of GNSS melt-down is eLORAN – ‘enhanced’ LORAN – a very accurate and relatively low-cost system.  It relies on powerful low-frequency radio transmissions from land-based sites that are much less vulnerable than the extremely feeble ones from satellites.  eLORAN doesn’t offer all the facilities of GPS but it is complementary and independent.  Several countries are developing eLORAN in order to provide ‘resiliency’ in the event of GPS failures – including the UK and Ireland.   South Korea too is on the case – as well it might be given that the North Koreans have apparently already been jamming GPS transmissions on their borders.  But the EU apparently still behaves as if there’s no problem – and there’s little or no informed public debate on the topic.

That’s the most alarming thing of all.

 

 

A revealing 1743 map at a grand country house

Ham House firescreen of c17

Here’s how much they knew about Australia (or New Holland as they called it then) back in 1743 – as revealed by an old fire-screen at Ham House, a National Trust property on the outskirts of London.  The west and north-west coasts are roughly correct but Van Diemen’s Land (now Tasmania) is very vague and still attached to the continent.  The whole east coast is conjectural and joins Papua-New Guinea in the north.  The discovery of the Torres Strait in 1611 remained unknown, at least in England.  Cook, Bass and Flinders had a lot of gaps to fill in over the next 60 years!