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    Re: Dependence on GPS
    From: Byron Franklin
    Date: 2009 Nov 4, 09:35 -0800

                                                         Dead Reckoning. A
    Second Opinion against EAG.
     
    Electronic Assisted Groundings.
    I agree with you, use everything available, if the situation is
    important or dangerous.  Electronic Navigation is tops. My experience
    using electronic equipment aboard nuclear submarine and surface ships
    is, it�s of extremely accurate with little down time. After using
    electronics you build a trust and faith. The equipment and their
    builders deserve, a �well done!� Certainly conventional navigation is
    harder to master, takes more time and is less accurate. The black box
    is best. So why, lose time with the least accurate, Including Dead
    Reckoning. I can get a fast accurate fix with the black box. But this
    can be the problem known as E.A.G.  Electronic black boxes fail to
    warn you when they don�t do their job. They always look the same.
    Humming and giving information. Right or wrong.  My most vivid
    memories are the few times the electronics failed. These are the times
    that make you take notice. Always it seemed to be at the wrong time.
    One very vivid memory (1964) was on a very sophisticated ship heading
    toward the Hebrides off Scotland. Dead Reckoning (D.R.) put us with-in
    the radar range of the high rocks and hills of the Hebrides. Our radar
    scope was clear.  Our charted D.R. time was quickly closing the
    entrance to �Little Minch�. Loran gave us a beautiful three point fix
    plotting on the chart to the west and north of the entrance.  I looked
    again at our D.R.as a �second opinion.� And, recommended to slow as I
    got another three point  fix, next to the first.  Should I trust the
    fix and come about? Shortly after, the lookout and radar suddenly
    picked up the Hebrides ahead. Two black boxes failed us (Radar and
    LoranC.) The D.R. although not accurate, was a warning based on
    information I knew to be near to correct, Course Speed and Time. A
    D.R. can be quickly checked to ensure the plot is correct. Before and
    after that time, I saw many three pointer fixes that proved wrong.
    Electronics are good and a god sent. But, in navigation, human input
    is a must for safety. The manufacture and salesman have a job to sell
    you on how good and reliable their black box is. Other seaman may tell
    you, how they safely transited shoal waters using only the black box!
    They are right! It has been done.  But, undue trust and faith in
    Electronics� has Assisted in many Groundings.  I think that the
    electronics are great, but I like seeing where I have been and where I
    am going, The DR. and the chart are my trusted friends and should be
    yours, No matter what equipment is aboard, your safety depends on a
    second opinion on that fix. When transiting always run a Dead
    Reckoning plot and file an underway plan.
    
    
    On Nov 1, 5:32�pm, Peter Fogg  wrote:
    > Lu Abel wrote:
    > > Peter:
    > > I've seen some themes in replies to your posting: �(1) �First and foremost,
    > > good navigators use ALL available information and techniques to assure a
    > > safe voyage.
    >
    > I've said as much myself, Lu.
    >
    > > To eschew any particular technique (eg, GPS because "it can't be trusted")
    > > is as silly and dangerous as to eschew any other technique (eg, DR because
    > > I'm too lazy and/or trust the electronic box too much to do it).
    >
    > I've also said that no eschewal is being proposed.
    >
    > > (2) �There are technologies to keep GPS sets working under pretty adverse
    > > conditions (eg, waterproof bags, even waterproof metal cases).
    >
    > And they are also prone to failure. �Even if they were perfect, the need of
    > the GPS for the supply of constant electical power tends to be
    > counter-indicative of successful isolation.
    >
    > "My understanding of �your point of view would be helped if you would
    > provide the brand names and models of these GPSs that failed you."
    > I can''t see how this information would be of any help at all, Lu, even if
    > it was data at my fingertips, which it is not. �And you appear to ignore my
    > repeated mantra that the failure of necessary supporting systems amounts to
    > the same practical effect as failure of the GPS box itself.
    >
    >
    >
    > > As for battery life, the rated battery life for a Garmin 76 is 16~18
    > > hours. �We all know battery capacity is reduced in the cold, so maybe it's
    > > less in a cold, water-soaked environment. � But "chewing through at an
    > > unsustainable rate?" � First of all, I use a 12v accessory cord off my
    > > boat's 12 v electrical system.
    >
    > And if your "boat's 12 v electrical system" should fail to continue to
    > produce power? �Remember that one wave through your open main hatch can
    > achieve this. �Or your motor failing to start, for any of innumerable
    > reasons for this.
    >
    > > � AA cells are suddenly replaced by a 90 lb lead-acid golf cart battery
    > > that's pretty hard to "chew through"
    >
    > No, it is very vulnerable in practice.
    >
    > > � I truly believe you have had some bad experiences with GPS. � But without
    > > more data on the exact details I have very hard time accepting a
    > > generalization to "GPS is an inherently unreliable navigation tool."
    >
    > Am not claiming that GPS is particularly bad; not compared with all
    > the different systems that tend to fail after a while at sea, for a great
    > variety of reasons. �With the greatest of respect Lu, you appear to be
    > missing the point, and I'm not sure how I can make it more clear.
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