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      In a lifeboat with a chronometer,tables, and compass (no
sextant), a navigator would be able to mark the GMT time of the sun's
limb on the horizon. The elevation is zero. Correct for refraction,
semi-diameter, and height of eye (dip). Perform normal sight reduction
and expect 6 minutes of arc accuracy under normal weather conditions.
Morning and evening LOP's may provide a running fix opportunity. Final
landfall would be made by sailing along an LOP to the destination. If
clouds threaten to obscure the sun at the horizon then estimate
elevation above the horizon by counting solar diameters to the lower
limb. One solar diameter at the horizon will be about 33 or 34 minutes
of arc. A finger width held at arms length equals about 2 degrees of
arc. Expect 20 minutes of arc accuracy up to 4 degrees of elevation.
The lifeboat compass can be checked for deviation at the same time.
     If given a choice , I would trade the chronometer for a sextant
and then latitude sail using Polaris, LAN, or a star's meridional
passage.

On Mar 7, 11:41 am, 40 South  wrote:
> Supposing one was in a small boat with an accurate timepiece and the
> necessary tables, how accurate could you determine your longitude by
> observing the rising or setting of the sun or any other celestial
> body?  Also, assuming you had a compass and were north or south of the
> tropics, would it be possible to estimate your latitude by taking a
> bearing of the setting or rising of a celestial body?
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