NavList:

Martin, very fun. :) I'm sure NavList members will want some numbers. Can you post any sight data? How many days did you have good weather for sights?

You wrote:
"A Pioneer Mark 2 classic sextant"

Not that it's critical, but many navigation enthusiasts might recognize this as a "USN Mark 2" sextant and call it a "marine sextant" rather than a "classic" sextant.

You wrote:
"This ship sails at about 20 knots constantly, which means that we cover 1 nautical mile every three minutes.Therefore, when taking sights of three stars or planets to get a simultaneous fix, the LOP’s must be advanced to adjust the distance covered and ship’s heading."

Wow, yeah, fast! And that implies running the sights forward in almost every case (unless you have the luxury of picking one sight abeam).

And:
"Since I could not follow the time of every heading change, when taking sights a few hours apart some LOP’s advancing errors might have been introduced."

Did you have any access to actual heading changes? In six hours, what would you estimate was the largest change in true course due to great circle track? In any case there's probably nothing much to worry about here. You could, of course, just estimate the actual change in position from a great circle. Although we're accustomed to thinking about advancing celestial LOPs by course and speed, what counts really is the offset in lat and lon, and you could work that up based on an assumption of a great circle path for the elapsed time. I doubt it would make much difference in your celestial fixes compared to a fixed course and distance run, but at that (high!) speed, maybe a little.

What's your plan in London? I imagine you'll squeeze in a pilgrimage to Greenwich, yes? Any other excuse for the trip? Or primarily for the celestial adventure? :)

Frank Reed