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    Re: Accuracy of sextant observations at sea
    From: Greg Rudzinski
    Date: 2010 Nov 25, 12:02 -0800

    Alan,

    You asked "What sort of boat or vessel are sextant shots made from?"

    For starters:
    1. Super tankers to canoes.
    2. Submarines
    3. Airplanes
    4. Blimps/Balloons
    5. Space craft
    6. Car/Truck
    7. On foot

    Probably not from a jet ski though ;-)

    "What sort of accuracy can be reasonably expected"

    Having done both small craft and ship CN I would say that 3NM is good aboard a sailboat and 1.5NM is good aboard ship. This is subjective opinion based on experience.

    To get 3NM accuracy aboard a sailboat it is best to average four or more observations. To get 1.5NM accuracy aboard ship I found that averaging was not necessary. It is always good practice to spend a few more seconds of time to swing the arc so as to be sure of perpendicularity of the sextant to the horizon.

    "How experienced is the shooter"

    Experience helps with sextant adjusting, observations, sight reduction, and plotting. Practice makes perfect. There is a point somewhere along the line when major blunders are routinely avoided. Subtle blunders are more difficult to discover but can be reduced also with practice.

    Just like calling shots in marksmanship you will be able to call your shots with the sextant too.

    Greg Rudzinski
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