At 04:53 PM 12/19/04 -0500, you wrote:

My major complaint with sextants is that of cost. For $1000 you can buy 10
GPSs with lithium AA batteries with which you can get a fix of almost
infinite precision. The batteries will still get a fix 10 years from now.
In the meantime, if you don't practice with your sextant you will be lucky
to be able to get any fix worth having.
A good sextant is perhaps more than $1000, but you can use one of the
plastic ones, which will get reasonable fixes for perhaps $200. On the
other hand, you can still get 2 GPSs and batteries for that amount. In any
event, you get my thinking. I know that this is a kind of heresy and that
Sextant religion is not to be trifled with, but I have a pretty hard headed
attitude about costs and benefits.

Yea, I know. About midnight the Sextant followers will gather around my
bunk, chanting. And, by daylight another heretic will have been burned at
the stake.

Mike

Capt. Mike Maurice
Tualatin(Portland), Oregon

I have a Davis Mark 25, about $200 new, cheaper on E-bay. I figured that the
additional precision of a really "good" sextant would be lost on me with a
small powerboat pitching around on the seas. The expensive one might be good
on a carrier deck or something more stable. Also, the additional precision
would probably be wasted on inexperienced me... operator error!

One other note. Like any backup equipment, take out those backup GPS' and
use them occasionally. For one, new Duracells expire in what... six years?
Don't let them sit around that long or eventually they will corrode and ruin
your equipment. Don't ask me how I know this. This past weekend, I pulled
out my Garmin 175 GPS / chartplotter to use it. Somehow, the "new" duracells
were dead. This usually means the power button got pushed along the way
while in it's case, but I don't know how this happened since it sits in a
metal box (faraday cage) untouched. Anyway, once plugging in to 12V power,
seems it had lost it's initial position fix, so it had no idea in the world
(literally) where it was. Had to reinitialize, and it took a LONG time to
acquire signals.

Once it finally had a good fix, I discovered that for some reason, the
chartplotter function wasn't working properly... it now doesn't want to
recognize the chip. Good thing I really didn't need the thing in an
emergency!

Keith
__
...at least I thought I was dancing, 'til somebody stepped on my hand.
----- Original Message -----
From: "Mike Maurice" mikem@yachtsdelivered.com

At 06:45 AM 12/20/04 -0600, you wrote:

Alkaline Duracells should not be left in any expensive equipment for even a
year without checking them. Even the expensive Lithium L-91's should be
checked once a year, to make sure they are not leaking or have had some
other kind of failure. The L-91's actually have some electronics in the
body and that part is possibly subject to failure, where the actual Lithium
part would still be ok.

GPS's should be turned on and run for 15 minutes (min) every six months or
so. Check the batteries. An hour or more would be better. The almanacs get
out of date and this info is what the GPS uses to decide which satellites
to try to latch onto. In any event, if you have any inkling that you may
need a GPS in a hurry, especially in rough conditions, it should be turned
on 15 minutes ahead of time. 30 minutes would be better. About once a year
I take all my GPS's  out and let them run for a couple of hours in a
location with as wide open a sky as available, and check all batteries.
Replacing any that seem down more than about 30 percent. If conditions are
really rough it is possible you will not be able to get a fix with a unit
that has not been on for a year or more; at all, until conditions calm
down. Keep this in mind. All this will be aggravated by having the antenna
located high up and subject to extreme motion, like on a mast.

I have never had any trouble getting a quick fix, if these guidelines have
been followed. But, I have had trouble when I did not use them. I am
suspicious that most troubles with getting a fix are related to some of the
problems mentioned above. There are so many misconceptions about that GPS.
There is no magic. These are just radio receivers with computers, and are
subject to the same problems as pretty much any other similar equipment.

Mike

Capt. Mike Maurice
Tualatin(Portland), Oregon