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     Reflecting on my years at sea, I would have to say that from the
bridge a L.O.P. intercept of more than three miles from a GPS or LORAN
A.P. would send me straight to the short wave for a time check
followed by a double check of the index error. Height of eye wasn't
easily checked underway. Today the underway height of eye can be
checked with a laser rangefinder. The last check would be almanac and
sight reduction calculations. Often everything would checkout good
which would put blame squarely on my ability to keep the sextant
perpendicular to the horizon. On a sailboat beating to weather keeping
the sextant perpendicular to the horizon is problematic. Developing a
good pair of sea legs is the remedy.G

On Jul 11, 8:52�pm, Anabasi...@aol.com wrote:
> In general, a merchant ship has from about 20-40 meters of height of �eye
> from the bridge. �On a 100 meter vessel, it is a bit lower, with �most larger
> ships around 30 meters.
>
> My normal Celnav fixes are usually within 3 nm and I am disappointed by �
> worse results. �Sunlines are usually within 1 nm when I use the GPS fix as �the
> AP, as are LAN observations.
>
> I don't envy those who need to shoot from small vessels. �I have never �done
> so, and can't say that I'd like to. �My worse conditions are 20 degree �rolls
> with periods of 10-15 seconds. �That can get irritating, but not �
> insurmountable.
>
> Jeremy
>
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