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    Re: New inovation in astro navigation?
    From: Lu Abel
    Date: 2010 Aug 2, 19:06 -0700
    Well put, Richard!

    If we're gong to distrust GPS, how about distrusting iron vessels (chemistry/metallurgy) and, worse, fiberglass vessels (pure alchemy, creating polymers out of oil).  Maybe we should distrust screw machines and go back to holding our wooden boats together with trunnels. 

    Navigation and vessel building are inherently conservative professions (unless you race boats).  Each of us has to decide what level of technology we feel comfortable with.   But the goal is first and foremost safety, and to eschew GPS (or radar, or VHF radio, or AIS, or any of a host of other technologies) because under some rare-to-impossible circumstances they might not work is wrong, IMHO.

    One thing the can't-trust-GPS-CN-is-the-only-way-to-go folks keep glossing over -- what do you do when it's cloudy??   There are endless records of vessels being wrecked because they were set by an unknown current or for some other reason were way off from their DR position (how about a whole fleet under Cloudseley Shovell?)

    I love to practice celestial navigation.  But to eschew modern systems because "they might not work" under some hypothetical circumstances is wrong.   An analogy:   I also love steam engines.  They are simple and easy to understand as compared to a diesel or jet engine, which are black magic.   But I'm sure not going to tear the engine out of my car and install a steam engine.

    Lu Abel


    From: Richard Reed <richard.reed@idnetfreemail.co.uk>
    To: NavList@fer3.com
    Sent: Mon, August 2, 2010 12:58:40 PM
    Subject: [NavList] Re: New inovation in astro navigation?

    Here's a setup for deep space navigation that uses expensive digital cameras mounted on a kind of acceleration-sensitive yoke for attitude measurement. A gross angle is measured by the yoke, and the fine precision by DSLR's with big telephoto lenses.

    http://www.psatellite.com/research/dsnav.php

    My opinion of 'electro-trickery' begins with immense respect for the recognition of the significance of double-reflection geometry and the progressive refinement of the precision available to hand in the sea environment. Also, if sextants were wonderful for this, what can you say about chronometers? It doesn't do to call them 'mechano-trickery', because for all the elegance of lunars, our failure to have a better natural clock than the Moon made mechanical timekeepers _necessary_. I guess trade would have progressed with all the shipwrecks anyway, but probably much more slowly.

    I forgive 'electro-trickery' for a lot of things. Do we need air transports? Forget all the fly-by-wire and flight management computers or even jet engines. To land an airplane when birds prefer to walk, you need eyes so much better than a bird that your lousy reflexes don't matter, and you have to see through clouds and fog -- electro-trickery in spades. A simpler example is ocean navigation in bad weather. The ocean approach to the English Channel from the south is fairly nasty in winter and full of ships. Best to have something better than light to steer or avoid others by.

    I'm still fascinated by the elegant beauty of CN, and apologise if I abuse the spirit of the list. I just think a lot of modern complications have their places.

    Richard

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