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  The objections to the use of equal altitudes of the sun around local
apparent noon are simple mischief, and they miss the most essential point
about celestial navigation in the age of GPS.  Most yacht sailors now resist
learning celestial at any level, because they consider that a GPS and backup
is more than they will ever need---and the backup can be purchased cheaply and
at less cost that a sextant and related materials and equipment.

  The point is, therefore, that for all those who are fully invested in their
own mastery of sights not on the meridian, and who therefore deplore the local
apparent noon methods, and who use all sorts of claims and disclaimers to
discourage others from doing so, a terrible disservice is being done to the
effort to teach enough celestial to make yacht sailors safe even if their GPS
and backups fail.

  The difference between teaching equal altitudes around local noon and the
use of sight reduction tables is a very significant difference.  In my class,
over four years now, I have taught both and found that the resistence to
learning how to reduce sights not on the meridian is increasing.  No one will
buy sight reduction tables anymore, and my friend at Armchair Sailor says it
is all he can do to persuade people about to sail into the Pacific to buy an
almanac.

  For those who claim that if the equal altitudes method were valid there
would be references to it in respected elements of the literature, I would
simply say that you have not looked into the literature before giving out an
opinion.  Hewitt Schlereth in his book on navigation by the noon sight
explains the equal altitude method and corrections for movement of the vessel
for those who want to reduce the small error induced by the difference in
position of the boat between sights before and after noon.  And Volume 3,
pages 157-160 of The Admiralty Manual of Navigation (1954) explains the equal
altitudes method and gives a correction table to account for change in
position of the ship between pre- and post-LAN sights.

  The principle of the equal altitudes method could not be simpler.  By
definition, the sun increases in altitude before local apparent noon at the
same rate as it declines in altitude after noon.  Local Apparent Noon is by
definition the moment when the sun reaches its highest altitude at your
position and is therefore on the meridian (either due south or north of your
position).  Everyone knows that the noon sight was used to determine latitude,
but the use of sights before and after noon is even more useful.

  If you take a sight at exactly 50 degrees sextant altitude before noon and
later, as soon as you know that noon has been reached by the fact that the
altitude of the sun does not increase, reset your sextant to 50 degrees, you
then wait for the sun to descend in the sextant until it is tangent to the
horizon and note the time.  Exactly mid-way between the 50 degree sight before
noon and the 50 degree sight after noon, as determined by the time of each
sight, is local apparent noon.  A brief look in the almanac for the Greenwich
Hour Angle of the sun at that moment yields longitude, and the time of local
noon is a good check on your latitude sight as well.

  By taking several such pairs of sights, a series of estimates of local noon
is made and the average of them yields an even more comforting check on the
time of local noon.  If, as someone said in a recent comment, the sun is being
obscured by clouds during the run-up to noon, start earlier and take as many
sights as possible.  (The same clouds that are conjured up by the nay-sayers
to get in the way of doing this are ostensibly clouding their sights for lines
of position, and once again they are doing a disservice to this simple and
precise procedure.)  This increases the odds of one or more pairs of sights,
even if the sun is being obscured after local noon, as before.  This procedure
can be used for sights taken relatively early in the  morning, well before
noon, if necessary, so long as they are matched by equal altitude sights after
noon.

  No one claims this method had advantages over the use of sight reduction
tables, because the methods are complimentary, not competitive.  What makes
the objections to the LAN method tedious and sometimes misleading is the
uninformed claim that the equal altitudes method does not appear in the
literature and must therefore be voodoo.  It is the objections that are in
deep voodoo, not this method that has saved, and will do so again, the
relatively inexperienced and untutored navigator who has dropped a GPS
overboard and is trying to cope with anxiety and forgotten instruction to find
a way home.

  For those, finally, who say this method has been tried and does not work,
remember that a large part of the success of any endeavor is attitude.  If you
don't want to use equal altitudes, because your private view of the world
might be threatened, by all means navigate as you please.  But stop trying to
discourage those whose hold on the theory, math, or practice of sight
reduction methods may be tenuous from saving themselves or making their
passage more comfortable by knowing this simple and effective way to sail to
any point on any ocean.

  I repeat my offer to xerox the Admiralty Manual pages on this method, or
Schlereth, for that matter, for anyone who will send me an email with that
request.  Surprisingly, or maybe not so surprisingly, those who on these pages
have written that there is no scientific or academic support for the equal
altitude method don't seem to want the pages from the Admiralty Manual to
contend with.  For shame.

                                       Mal Misuraca
                                       "Celestial in a Day"
                                       San Francisco
                                       415-546-6430
                                       Aliscafi@aol.com
                                       mamlawsf@aol.com


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