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    Re: Dependence on GPS
    From: Peter Fogg
    Date: 2009 Nov 2, 09:32 +1100

    Lu Abel wrote:
    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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