NavList:

George Wrote

 

"Jeremy says "the latitude is consistently off", but it's only a mile out
from GPS, according to me, so nothing to be ashamed of there. Indeed, it's
well within the margin of error that can be caused by natural changes in the
refractive part of the dip. Rather more interesting, to me, is the scatter
in those Moon altitudes. I wonder why. Was the sea state good, at that time?
Often, with a high Moon, contrast can be low, especially if the sky is a
touch milky. That gets worse if you use an all-over horizon mirror, rather
than a half-and-half split job. If Jeremy had recorded a number of altitudes
for the Sun, as he did for the Moon, I wonder whether thet, too, might have
shown scatter. What's his experience?"
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The sea state was fine at the time, with only a easy roll.  The trouble was the moon/horizon contrast was quite low and therefore the exact limb was difficult to determine due to a bit of haze.  I also find that regularly my daytime moon shots are not as solid as my sun lines, which provide an excellent limb most of the time.  Sadly, I had no time to shoot additional sun lines.  As for hardware, I was using the Tamaya, which has the classic split glass/mirror horizon array. 

 

Jeremy

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