Cleone - CLEONE Leg 24 Day 7 - Where are we?

We know where we are to within nine feet.

 

Well, that's a pretty bold statement, and it could do with a bit of examination!  Cleone's GPS tells us exactly where we are to 3 places of decimals, and it also tells us what our position error is - at the moment 11 feet.  And if it's good enough for the GPS, it is good enough for me.  Moreover, we watch the "Miles to Go" figures and the "Cross-Track Error" carefully - we like to know exact answers.  But when we are at sea, we go for days without seeing another ship,and we are often hundreds if not thousands of miles from land.  So, for much of the time, pinpoint accuracy is irrelevant; but is it important?

 

Not so many years ago, in the late 1980s or so, very few ships, let alone cruising yachtsmen, had GPS.  They carried paper charts, and knew where they were, more or less, particularly when they were near land and could take a few bearings.  Lighthouses and buoys were numerous, accurately charted, and the significant ones were lit at night.  If they were off-shore, and could not see land, things were a bit more hit and miss.  Naval vessels, and presumably cargo ships, had an accurate Intertial Navigation system.  For the yachtsman, when he or she was in and around Europe, there was the Decca system or Loran.  These little black boxes made use of radio waves send out from various transmitters and told you more or less where you were.  Offshore, aids such as Radio Direction Finding were available.  They were useful, but again, not very accurate.  If you were ocean sailing, then you used a sextant and Sight Reduction Tables - even in the 1980s aircraft navigators used the same system.  Specialist navigators in the Royal Navy, product of a two-year course, claim to be able to fix their position to the nearest 400 metres or so using clestial navigation.  Yachtsmen would be pleased if they could fix there position to the nearest couple of miles or so.  When they got close enough to land, hey presto, lights appeared, out came the relevant chart and soon every one was happy.  But because everyone now uses electronic aids, many lights are no longer properly maintained - although we are lucky in Europe and various other places such as the US and Australia that this is not the case. 

Today, electronic navigational systems on naval and merchant ships are universal, as it is on most every yacht.  Paper charts have been superceded by electronic charts and GPS systems.  It is virtually impossible to get a marine GPS without a chartplotter.  Regardless of lighthouses, buoys and other navigational marks, the GPS tells everyone exactly where they are, and we all assume everyone else we meet knows exactly where they are too.  As electronic systems become cheaper and cheaper, paper charts are becoming more expensive and more difficult to get hold of.  Many yachts simply do not bother with them any more.  So we rely more on the gizmos and less on printed materiel and what we can actually see around us.  Provided the chart plotter is working properly, the GPS working out the position shares the same datum as whatever chart package is being used, the radar is getting a clear picture, and we can talk to everyone else, this is fine.  But is it sensible?  As we have found during this Rally, chart packages sometimes don't use the same datum as our GPS, and maybe the same could be true of a ship we are approaching.  At anchor or in a marina, the chart-plotter shows us as being ashore.  The old military dictum remains true; assumption is the mother of all cock-ups*

 

Paper charts and pencils are not affected by lightning strikes or by electrical failures.  The magnetic compass remains as accurate as ever, as does a piece of line with a lead weight and paint marks every metre.  And the Mark I Eyeball remains the single most reliable, accurate and flexible tool for navigation, position fixing and a number of other entirely unrelated tasks.  Don't decry the modern aids, use them in their place, but neglect the basics at your peril.

 

We have had another day of cracking trade-wind sailing, with 169 miles in the bag.  And today we have sun-shine as well.

 

Meanwhile, all is well with us, and very best wishes to you all.

 

James, Paul and Volker