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    Re: Level of observation accuracy in medium seas
    From: Robert Gainer
    Date: 2004 Jul 22, 22:25 +0000

    David,
    Do you think that a large breakfast would affect the precision of the
    observation or the accuracy of the results on this noon sight?
    Robert Gainer
    
    
    
    >From: David Weilacher 
    >Reply-To: Navigation Mailing List 
    >To: NAVIGATION-L{at}LISTSERV.WEBKAHUNA.COM
    >Subject: Re: Level of observation accuracy in medium seas
    >Date: Thu, 22 Jul 2004 16:28:22 -0500
    >
    >An experienced navigator should be able to determine he was in or near lake
    >michigan during daylight hours (and if he was hungry, that would indicate
    >somewhere around noon or American)
    >
    >
    >
    >-----Original Message-----
    >From: Bill 
    >Sent: Jul 22, 2004 4:13 PM
    >To: NAVIGATION-L{at}LISTSERV.WEBKAHUNA.COM
    >Subject: Level of observation accuracy in medium seas
    >
    >Had a chance to make my first "on water" observations last weekend.
    >
    >First sun shot was from the pier using short dip and was right on the money
    >(according to GPS fix).  Better lucky than good ;-)
    >
    >Second was a bit more challenging.
    >
    >Location: Lake Michigan near Michigan City (southern end of the lake).
    >Boat: 34' Catalina fin keel with tall rig (36' Catalina mast and sails)
    >
    >Day before on the water:
    >
    >* Wind out of the north (started 005d and backed to 340d)
    >
    >* Started at 12-18 kn, end of day 18-23 with puffs to 28+ (true, not
    >apparent).  Headsail at 110, 1 reef in main.
    >
    >* 4-6 foot confused seas.  By day's end waves in the 8 foot range were
    >forming.
    >
    >Day of shoot:
    >
    >* Wind still out of the north (started 005d and backed to 340d again)
    >
    >* 10-15 kn true, puffs to 19+. 150-130 headsail, full main.
    >
    >* 3-5 foot confused seas.  By day's end waves in the 6 foot range were
    >forming.
    >
    >* Course 274 true (just above beam reach). Heel 12-22 degrees.
    >
    >* Slight haze, visibility approx. 15 nm.
    >
    >*  Approx. 8 nm off southern shore so had the horizon backed by sand dunes.
    >
    >Did a noon sun shoot within seconds of local noon with 0 magnification
    >sight
    >tube.
    >
    >Question:
    >
    >What degree of accuracy (range?) would an experienced sextant operator
    >expect under these conditions:
    >1. With 0 magnification sighting tube
    >2. With 4X telescope
    >
    >
    >Dave Weilacher
    >.US Coast Guard licensed captain
    >.    #889968
    >.ASA instructor evaluator and celestial
    >.    navigation instructor #990800
    >.IBM AS400 RPG contract programmer
    
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