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In the book of Muir, Treatise on navigation and nautical
astronomy, Annapolis 1918 (a textbook for the Naval academy)
the author writes about anomalous dip very briefly, but he says
"One has to be especially careful in the Red Sea and in the
persian Golf".

(I was looking yesterday whether any dipmeter was ever mentioned
in any standard Western navigation book accessible to me.
No.)

On Mon, 22 Nov 2004, George Huxtable wrote:

> In the Red Sea, I understand, navigation is bedevilled by the presence of
> many local low reefs, and where these dry out and are heated by the Sun,
> then that's likely to give strange values of dip for a body seen over that
> reef. And in those special circumstances the dipmeter will provide an
> imperfect correction, because, as Jared pointed out earlier, it's averaging
> dips in two opposite directions. So, as usual, the navigator has to
> interpret his information with some caution.

Alex.

   

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