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Peter wrote:
"If a zenith body can be found  and identified then the boat's position is
known."

And George  replied:
"No, it isn't. Not unless you know the time. How do you get that,  without
any instrument?"

To which Peter replied:
"To put that  another
way, how would he not have at least a rough idea of the time? Lack  of
precision is not necessarily the same as lack of accuracy. Folk without  a
written language tend to have great memories and compensating skills we  may
find difficult to comprehend. Without a clock they may get better,  for
example, at estimating the passage of time. Remember that the  apparent
movement of the stars across the night sky is itself akin to a giant  clock,
or reference. The point I was trying to make, that I took as the moral  of
Creamer's accomplishment, is that nav should be a holistic process.  We
should be ready to embrace, or at least consider, all possible  methods."

WHOA! er... Peter...?
Yes, by watching the apparent  movements of the stars (and knowing the day of
the year) you can get a good idea  of the local time, which is nice for
planning your midnight snack. But without  some instrumentality, like a sextant
with an almanac for lunars or a  chronometer, or some repetitive, predictable
signal available over tens of  thousands of square miles, like a satellite
signal, there is no way to get any  type of absolute time, and therefore no possible
way to get anything but a very  rough value for longitude astronomically, and
no value at all that would be  useful for navigation. Local time alone is
useless for navigation. Yes, you can  get a rough value for LATITUDE by watching
zenith stars. But there's nothing in  that technique that can supply longitude.

Of course there are other ways  to get longitude non-astronomically out of
sight of land without instruments or  calculation or communication with other
vessels, such as watching for swell  patterns, spotting land birds, noticing
animals and algae found only in certain  locales or in proximity to land,
detecting evidence of certain specific  currents, sighting clouds that form only
above land, seeing mud in the water,  detecting a change in salinity, and so on. A
lot of modern drivel has labeled  these techniques as "indigenous" navigation
and claimed that these methods  represent some special "Polynesian
knowledge", for example, unknown to western  science. In fact, these methods were in
common daily use among navigators from  "Western" civilization as recently as 150
years ago. The fact that navigators  from other cultures ALSO knew these
methods is very interesting, of course. It  tells us that they had a 'culture of
navigation' since this information takes at  least a few generations to
accumulate.

-FER
42.0N 87.7W, or 41.4N  72.1W.
www.HistoricalAtlas.com/lunars

   

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