Next message: Frank Reed: "Re: The lost expedition of La Perouse"
George H wrote:
"Well, if I had a crew member would be devoting the next 40 - 60 minutes to
such closely-spaced observations as Frank has suggested, I wouldn't expect
much useful boatwork out of him in the 2 or 3 minute free intervals in
between."
LOL. Well, maybe if they're so busy manning the oars on that slave barge you
operate, then they wouldn't have time for sights! <g> <that is a joke> More
seriously, as I have already said (and I think it's obvious) there is no
requirement to take the sights spaced as closely as you are implying.
I think that if one has time for celestial at all, then this method I've
described is no worse than any other approach when it comes to the time
required. I haven't the slightest doubt that a navigator could make and eat lunch and
do this sight run, too.
By the way, in another post you commented on the fact that you need speed
over the ground which means you would need to correct for any current. That's
true, of course, and it applies to ALL running fixes. One recent post pointed
out that many people using standard celestial at sea just shoot a couple of
sun sights during the day, likely separated by quite a few hours, and then
bring them together as a running fix. If they're in a 2 knot current, and the
two sun sights are separated by six hours, this could easily lead to an error
of 12 miles in the fix. That's standard LOP navigation. That there is a
moderate error from ignorance of current in the lat/lon by noon sun technique that
I have described is not a problem of this method per se.
Also, something like 75% of the world's ocean surface has currents below 1
knot, and around 90% has currents below 2 knots. Those areas with higher
currents tend to be fairly stable, e.g. the Florida Current portion of the Gulf
Stream is basically always in the same place, and anyone sailing those waters
better know that before they start thinking about sextants and celestial
navigation.
And just for fun: What's the most famous ocean current? Three years ago, it
was probably the Gulf Stream, but that title now almost certainly goes to its
down-under counterpart, the East Australian Current or EAC. Thanks to a
computer-generated turtle and a couple of little fish in a Disney movie, this
ocean current's name has become known to hundreds of millions of people
worldwide.
-FER
42.0N 87.7W, or 41.4N 72.1W.
www.HistoricalAtlas.com/lunars
