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 Nigel wrote:

> Thank you for your note Steven,
>
> The purpose of going on the nav group was to see if anyone had come up with
> a different way of tackling the problem which is why it was rather broadly
> stated..
>
> The point of my exercise was to explore the feasibility of establishing
> longitude from a cleared LD other than using tabulated LD's from the
> Almanac (which of course are no longer tabulated). I have tried calculating
> HA moon from dec.star, assumed dec. moon and LD but of course end up with
> some tedious iterations and doubtful accuracies.

I don't get the point. Also, I don't understand how you compute the Moon's
Altitude without putting your zenith/horizon reference system into the
equation.
>
> Regarding watches, calcs etc, my own view is that if one wishes to use such
> exercises as LD's then they should be done by hand with logs of the time,
> usually Norie's 1805 edition (I do have earlier tables but they are a bit
> fragile)

Yep. I saw what I did as a first experiment. One of the major difficulties is
getting an accurate measurement. It's relatively easy to bring a body down on
the horizon, but it's something completely different to bring it diagonally to
the moon. I didn't want to pre-set the sextant to the approx. right angle
because that is a _serious_ form of cheating, in my opinion. You need to know
Greenwich Time it.

   

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