NavList:

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.

 

Jeremy

 

PS Irvin, QRA?

 

 

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.
Position 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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