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".....Let's remember that the basis of nav is a DR plot.  Knowing where you 
start from, then tracking movement over time.  Everything else is just ways 
of checking that plot.  This is the real reason why GPS is so potentially 
dangerous - when it fails, or the necessary supporting systems fail to allow 
it to do its miraculous stuff, then the poor silly sod has no idea at all, 
instead of having quite a useful idea that is regularly updated, albeit a 
derived position that can probably stand some refinement.  Dependence on GPS 
doesn't encourage people to look carefully at their environment on an ongoing 
basis and think constantly about how what they see can be useful information. 
 Traditional nav does this...."

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This is a very powerful argument ... and quite correct.  I support it 
wholeheartedly.   I think 'modern' GPS has most likely suppressed traditional 
navigation to the detriment of practical sailing and safety.  I experienced 
it's insidious effects for myself recently for the first time, and, shame  to 
admit, was sucked into its seductive charms myself.  I'll explain:

With a recent sailing trip a couple of weeks ago across the English Channel 
for the first time in many years, (Portsmouth to St Vaast Brittany)  it was 
made on a brand new all-singing, all-dancing, everything done from the rear 
cockpit Bavaria 39.

A lovely boat...but.. NO going forwards to change the headsail(s): it has 
furling jib;  No going forward to the mainmast to haul mainsail or to reef 
same, it has single line reefing; ALL done from the cockpit; 
....and NO need to bother about _navigating_: all done on a GPS run console in 
front of the wheel.  Just watch the 'telly' ('tube' for Americans)  as you 
sail along, occasionally looking up out at the waves and horizon ...!
It even has a little boat-shaped icon which swivels around on its axis to show 
where you are making track so you can see if you really are going the way you 
are pointing. 
As my (sailing) neighbor said afterwards when I mentioned it:  "_that's_ not 
proper sailing; there's no discomfort and challenge to it!"

Very nice and comfortable sailing though it was, it did emphasize to me though 
how seductive GPS must have become, with the sheer ease of becoming utterly 
reliant on the equipment through laziness, and most probably therefore little 
to encourage new generations of sailors to do _proper_ navigation even if it 
is fairly basic as a get-you-home-safely exercise.  It was so _easy_ to just 
switch on and look at the box.

There was one other important point that struck me though ... twice on the 12 
hour trip (going and the other coming back) the damned thing started to beep 
at regular intervals. When I asked what it was trying to tell us - Chris Gill 
the owner said the battery was getting low, and he had to start the engine 
and run it a short while to top up the battery.

Now I don't know if his battery was in a poor state and needed replacement and 
could not hold the charge; or if the GPS was using such a large amount of 
power it discharged a perfectly respectable battery fast;  but there was one 
thing for certain:  on  a long trip that engine was going to have to be run 
every day to maintain a navigation plot with the Garmin GPS kit.

A chart; a sextant;  cheap crystal controlled clock (as proven by Garry 
LaPook) and almanac would be much more sensible to me I think ... but then I 
am 'old- fashioned' in many ways.

Douglas Denny.
Chichester.  England.

=================================

Original Post:

Frank writes:


    If you're going to claim that those waterproof bags are just another 
technology waiting to fail, then you have to apply that same standard to 
traditional methods of navigation. Do you store your chronometer in a 
waterproof bag? How about your spare chronometer?


Sure.  These may be good ideas.  Over time the watches that are less 
waterproof fail to proceed and get replaced.  The aim is to have back-up 
systems, ideally ones that can perform the same useful functions as those 
being backed-up, but not vulnerable in the same ways.  So motors to augment 
sails, oars to function in the place of recalcitrant outboards, kerosene 
(paraffin) lamps in case the electricity supply goes (or just to preserve 
battery power), tinned food if the fish don't bite, and so on.  Traditional 
methods of nav for when the GPS has an issue.  Nah, forget that one.  Nav is 
a whole mindset, not just an alternative methodology.  Its about being aware, 
in a wide sense.


      So what to do... carry a cheaper handheld GPS that you can turn on when the main system fails. 


Frank, Frank.  Impractical in practice.  Those things take quite a while from 
cold to become functional, then continue to chew through those little AA or 
even worse AAA cells at a quite unsustainable rate.  You couldn't carry 
enough cells to cross an ocean with.  They are only for occasional use, 
assuming the nearest Wal Mart is always close-by.  Yes, you could use 
rechargeable cells, with a solar system to do that, and then you have another 
system to maintain while you wait for it to fail.  I'll say it again, 
sailboats provide terrible environments for even robust equipment.  Sailing 
involves a lot of fixing stuff or learning to do without it.
 

    Let me ask you this: if you met someone planning on doing some 
long-distance sailing, and they said to you, "I'm planning on taking a 
carefully stored handheld GPS for backup in case the main satnav system 
fails", would you advise AGAINST taking that backup GPS?? Do you not agree 
that the very great majority of the cases where the main satellite system 
fails can be answered simply by breaking out the spare and using it properly?


I think this person would be much better advised to learn to navigate, and not 
be dependent on electronics to do it for him/her.  

Let's remember that the basis of nav is a DR plot.  Knowing where you start 
from, then tracking movement over time.  Everything else is just ways of 
checking that plot.  This is the real reason why GPS is so potentially 
dangerous - when it fails, or the necessary supporting systems fail to allow 
it to do its miraculous stuff, then the poor silly sod has no idea at all, 
instead of having quite a useful idea that is regularly updated, albeit a 
derived position that can probably stand some refinement.  Dependence on GPS 
doesn't encourage people to look carefully at their environment on an ongoing 
basis and think constantly about how what they see can be useful information. 
 Traditional nav does this.


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