On Fri, 06 Oct 2006 05:30:57 -0500, Geoff Schultz
wrote:

Does the hours of sunlight follow the rule of 12ths? I suspect that it
does, but I'm too busy to figure it out by myself and I thought that
someone might now the answer off the top of their head.

-- Geoff

Hi Geoff,
I am not quite sure what you are wanting but this may be of help. It is in a way
similar to the estimation provided by the rule of 12ths.

When you wish to roughly ascertain the remaining hours of daylight at sea, hold
your hand at arm's length towards the setting sun and bend it so that your
fingers and palm are at 90 degrees to your arm with your fingers tightly
together side by side and are horizontal.

Bring your hand down beneath the sun so that the bottom of your little finger
lies along and just touches the horizon. The distance in finger widths between
the horizon and the bottom of the sun disc is the number of 15 minutes periods
before sunset.

e.g. four fingers is one hour of daylight left. You can easily make a rough
estimate of the time until sunset this way. I know that one could look up tables
or even look up the page in the GPS that shows sunset at destination, but in mid
passage or when making landfall, it works well enough for me and is surpisingly
accurate. One could possibly get into arguments about degrees from the equator
but I don't care to go down that route.

I hope that my explanation is easy to comprehend.

cheers
Peter Hendra
N.Z. yacht Herodotus