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    Re: SOA vs SMG or SOG
    From: Irv Haworth
    Date: 2009 Oct 26, 15:21 -0700
    Thanks for your input. I may try to query WMO for an explanation, but thought best to try members of this group as a starting point.(meaning aside from usual texts, Dutton,Weems, Mixter,Bowditch, Colter, Hobbs { US Naval Academy} etc.)
    Re your "QRA ?" Not sure of exactly what info you want (name of vessel or my address  ) so will give the you two answers.
    As a ham radio operator ashore my call sign is VE7CVL. (When I'm sailing off shore in my 40 foot ketch it's  VE0SAO. Name is Irvin F Haworth and live in West Vancouver BC Canada general email [ irvhaworth@shaw.ca ]
    The name of my vessel is La Brisita  ON 804819  , MMSI 316007738 . Call Sign CFG 7512 .

    From: navlist@fer3.com [mailto:navlist@fer3.com] On Behalf Of Anabasis75@aol.com
    Sent: Sunday, October 25, 2009 5:53 PM
    To: navlist@fer3.com
    Subject: [NavList 10277] Re: SOA vs SMG or SOG

    This report is completely different than the one's I've ever submitted from the ship.  Our form dates back to the telegraph days and things are sent in 5-number code groups.  It isn't done by telegraph any longer, but either SITOR or INMARSAT these days.  In any case we don't give data that looks anything like this report.
    I never even noticed the term they used for speed but we enter a code group for a fairly large range of speeds (4 or 5 knots if memory serves) as well as direction.  We don't even have to calculate a distance run, just submit position to the tenth of a degree.  We submit reports every 6 hours unless certain criteria are met such as winds over 100 knots or close to a tropical cyclone.
    As far as the term SOA vs SMG vs SOG we don't use them much, we just say "what's our speed" etc.  There just isn't much debate about the technicalities of it all.  About the only time I am truly concerned is if we are talking about ARPA (radar) inputs where SOG from GPS inputs can differ significantly from Speed through the water from the Doppler log.  The theory is that the rules are based on the relative angles of the two ships' headings which can vary quite a bit from the actual track vectors that SOG of the ownship would provide when compared to the radar echos (ie inaccurate CPA solutions).  I have not seen this problem too often in practice however, and nearly every ship I have sailed on uses GPS for radar input instead of the notoriously inaccurate speed logs that are installed on the ships I tend to sail on.
    PS Irvin, QRA?
    In a message dated 10/20/2009 9:25:30 P.M. Eastern Daylight Time, irvhaworth@shaw.ca writes:
    I'm somewhat perplexed over current usage of abbreviations: to wit the old (last 25 years ?)  standard meaning of SAO (speed of advance) versus what  I believe is the current view as presumably held by WMO (World Metro Org. ) who supply ships with free equipment and training to report weather..VOS (Voluntary Obs ...)
    What follows is an slightly edited (name of ship etc removed by me) recent report.
    The noon to noon report based on positions shows 425 NM ( my Rhumb calc. gives 424.5 NM) which they report as a SAO of 17.7 kts.
    To me the SAO should more rightly be termed the SMG (speed made good) .
    I contacted the webmaster but despite being an old US Navy chap had no idea.
    Hopefully some members might shed some light on matter for someone who may have slipped a notch or two without realizing the new movement....hi..hi
    himself aka Irvin

    Last reported at 2009-Oct-19 12:00 UTC. Time now 2009-Oct-19 18:30 UTC.
    S 17°12', W 179°42'.

    Wind from 160 at 14 knots

    Waves 1.0 meters (3 feet), 10 second period

    Barometer 1012.0 mb
    Air temperature 25.0 ° C
    Dewpoint 19.1 ° C

    Notes date/time lat lon naut. miles run SOA wind from knots barom. wave height air temp dew point water temp
    2009-Oct-19 12:00 S 17°12' W 179°42' 425 17.7 160 14 1012.0 1.0 25.0 19.1
    2009-Oct-18 12:00 S 15°00' W 172°42' 50 16.6 120 12 1010.2 1.5 26.0 21.8
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