NavList:

Maybe I've missed something but the obvious approach seemed to be to calculate Latitude by two altitudes then iterate the Moon fixes to get time and Longitude. I would not expect the Longitude to be that good given the azimuths of the sights.

I'd never tried to do this for real and using the rather long sequence of formulae (nicely described in Henning Umland's work) to get the two possible latitudes from the star sights proved frustrating. I can't see much likelihood of getting a reliable answer without a tested computer program. It's so easy to get terms mixed up. Is there a better way of calculating the Latitude, I suspect not?

Anyway, on safety grounds I'd decided to turn back on the basis that North America was pretty easy to find if I went westwards and there's quite a lot of sea if we missed Bermuda. Thanks Frank for a testing problem.

Happy New Year

BobC