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    Re: lifeboat navigation
    From: Geoffrey Kolbe
    Date: 2002 Oct 24, 08:31 +0100

    At 15:56 23/10/02 -0400, Jared Sherman wrote:
    
    > < what navigational items are appropriate to pack in the ditch bag?>
    >Arguably, a Globalstar or Iridium phone. Welcome to the Very Small Planet.
    >
    
    Having a means of communication from a life boat is fine. But having
    alerted the authorities that your boat has sunk and you now need picking up
    from your lifeboat, the first question is going to be, "What is your
    position?" It would be nice to be able to give them an answer....
    
    Even if you have no communication and your lifeboat is just drifting with
    no means of effective propulsion, it is still a very good idea to know
    where you are. As you drift into known shipping lanes you know that now is
    the time to stay extra vigilant, for example. Knowing where you are enables
    you to manage your resources of food, time and energy in a more efficient
    way and that can be the difference between life and death.
    
    In my opinion, it would be foolhardy to rely on remembering your last fix,
    or being able to carry navigational data and/or navigational equipment from
    your boat to the lifeboat as your boat sinks. You may not have time. It
    would also be foolhardy to rely on the phone or radio stored in the
    lifeboat to be working. I think it is essential that some form of
    navigational equipment should be stored _on_ the lifeboat.
    
    The nature of that navigational equipment is a matter of debate, but
    battery life has to be a, if not the, big issue of consideration. Lithium
    batteries may have a good shelf life, but once you start using them in the
    GPS, they are not going to last long.
    
    What does have a good lifetime - more importantly, a good usable lifetime -
    is a quartz watch. I am wearing a Casio watch that I found in a field eight
    years ago - it still has the same battery in it now that it had when I
    found it!
    
    To my mind then, the best navigational pack for a lifeboat would be
    waterproof box, inside of which is a sextant, a world map (which can be a
    single chart or a series of charts) showing currents and shipping lanes,
    three or four cheap quartz watches whose rates are known and a long term
    almanac, (my own "Long Term Almanac for Sun and Selected Stars,"
    naturally,) some sight reduction forms, a scribbling pad and some pencils.
    If the watches are waterproof, this will still all work if the lifeboat
    fills with water and these items are bobbing about until you can get the
    water out again. A calculator or a GPS may not be so obliging.
    
    The only maintenance required for such a navigational package would be to
    change the batteries in the watches every five years, calculating their
    rates and resetting them to exact GMT as you do so.
    
    Geoffrey Kolbe.
    
    
    Dr Geoffrey Kolbe, author of "Long Term Almanac 2000-2050" for sun and
    selected stars, with concise sight reduction tables.
    Available online from www.pisces-press.com
    
    
    

       
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