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    Re: Emergency navigation: a Cruiserfix tool.
    From: Frank Reed
    Date: 2016 Sep 1, 09:16 -0700

    Bill Lionheart, you wrote:
    "You would have to be really lost for it to be any help!"

    Yes, this device is no better than an estimation tool and could easily be counted as a celestial navigation "toy". The level of accuracy you could expect from a device like this standing on solid ground, with a sea horizon visible, is on the order of +/-15 minutes of arc at best and in relatively benign ocean conditions +/-30 minutes of arc (at the 1 s.d. level). A hundred years ago, that could have been useful. No more. It's a fun device with some clever features, good for entertainment, but its practical value is almost nil, limited by this very low accuracy level.

    Tony wrote in a another message:
    "I only have the translated reprint by another magazine stating that a novice in navigation could - in favorable conditions - fix his position to within 2 miles of the obtained by regular means."

    Clearly there are a lot of ways for this to be misinterpreted since the text is second-hand and he noted from a translated reprint. There is absolutely no way that this "Cruiserfix tool" could provide position fixes accurate to within 2 miles repeatably. Not a chance! Well, there's a small chance: by random luck if you have typical errors with a standard deviation of 30 miles then you'll be within 2 miles something like 5% of the time --that's blind luck.

    Just to reiterate, the very low practical value of this device in no way diminishes its entertainment value, and it also might find use in teaching.

    Frank Reed

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