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First of all, any skipper or navigator who doesn't look out the window
frequently is stupid, just plain stupid (see my previous post about the
59' sportfisherman that rammed a sailboat, killing the skipper, in
totally clear weather because the sportfisherman's skipper was "entering
waypoints in his GPS") (since since this started with submarines, let's
agree to exempt them ).

At the same time, I find this Hampton Roads USCG posting a bit more on
the "beware of the bogeyman" side than on rational navigation.    Let's
say their their hypothetical ship is traveling at 15 kts (certainly
pretty fast for conditions of reduced visibility).  That's a nautical
mile every four minutes or 1500 feet every minute -- or 150 ft every six
seconds.    I'd sure like to hear of an electronic charting system that
would take more than six seconds to update a track line!   So at worse,
the track line might be off by 150 feet.   On the other hand, they
advise taking fixes "every three minutes"   That means fixing the
vessel's position every 3/4 of a mile (not counting the uncertainty
introduced by the time it takes to actually plot radar or visual
bearings).   If I were navigating a ship, I'd sure rather know my
position to 150' of accuracy than to 3/4 mile.

IMHO, it's OVER reliance on electronic navigation that is the danger,
not using it intelligently while keeping an eye out the window, that
causes problems.

Yours for truth and rationality,

Lu

hch wrote:
> It may be of interest to some to note the following excerpt from "USCG 
Safety Alert HMRMS04-7", regarding Navigation in restricted visibility, as 
issued by Sector Hampton Roads on December 13, 2007, particularly the 
apparent time delay for a track line to upedate on an electronic chart.
> It seems that such a time delay could have rather far reaching implications.
>
> Excerpt ...
>
> "TAKE FREQUENT POSITION FIXES. Too often mariners fail to appreciate the 
importance of frequent fixes while navigating in restricted visibility. Over 
reliance on radar and electronic navigation systems can cause a mariner to 
lose situational awareness, in part because of time delays while the image is 
refreshed. A vessel can travel several hundred yards, especially if the 
operator fails to reduce speed, in the time it takes for the track line to 
update on an electronic chart. In some cases it may be necessary to take 
fixes as often as every three minutes."
>
> Regards,
>
> Henry
>

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