On Fri, 03 Mar 2006 23:11:04 -0500, Wayne.B
wrote:

The best backup for GPS is another GPS, and
some spare batteries.

Agreed. I have two, Old Handheld and Older Handheld, plus Really Old
AlphaNumeric Trimble Unit on the Nav Station that is the Most Accurate
of All.

But I also know coastal pliotage and carry a sextant, because things
get dropped, batteries fail and GW Bush can turn GPS off if the
terrorists are winning, or if he feels like it. (Doesn't matter once
Galileo's operational, I suppose, but that's another story).

So as long as I can see the shore, hear the surf, smell the land and
persist in carrying paper charts, odds are good that I'm covered.

I find that the GPS is handy in CONFIRMING my location (as far as that
goes), but navigating with it is strictly optional. It's an aid, one
of many, not a final arbitor or a second skipper.

R.

Courtney Thomas wrote:
Jeff wrote:

Gary wrote:

otnmbrd wrote:

That same bolt of lightening will take out your calculator so you
then have to work stars long hand. It'll also kill your digital
watch and radio so you won't have the correct time. It'll probably
short out your boat so you won't be able to work the stars out
until light the next morning. The lightening excuse to learn astro
is BS. Learn it because you want to or take a couple extra
handheld GPS. Practice dead reckoning. Know where you are all the
time.

Gaz





Let's see...... calculator gone, long hand star calc's....add a
minute or two to the solution.
digital watch killed..... in that case I'm probably dead too so
what do I care.... always have a mechanical clock that you know the
error...no big deal, was done for years.
lights out?....lite a candle or wait till daylight.... what the
hell, it's offshore navigation, what's the rush....



And how did you check the error on that deck watch? Radio? What was
the error and how much does it change daily? Can't just do the time
check anymore. Damn lightening.



With all due respect Gary, I think you need a refresher course on
celestial. I wear a "windup" watch, and have two windup ship's
clocks. All of them are accurate to a minute a month, and have a
pretty consistent error rate. I generally set them once a week, so the
error is well under a minute. So, would you care to tell us what the
expected error would be for both Latitude and Longitude?

To be honest, I don't really buy the lightning argument either. But
I'm not sure some find fault in celestial because it is not accurate
to 3 meters.


Jeff,

I'd be very interested in your opinion of where to get an inexpensive
but reliable "windup" clock/watch ?


Did I say inexpensive? My watch is an older Rolex, and the clocks are
both Chelsea. The most accurate of the three is a WWII deck clock I got
for about $250. My point is not that windup watches/clocks are perfect
backups for their more modern counterparts, but that in a pinch
electronics are not necessary for navigation. Latitude can be
determined without time, and longitude can be determined within 30 miles
even with a few minutes error. Not great for long passages, but good
enough to get you home.

BTW, my father-in-law spent 17 days in a lifeboat at the end of WWII.
He was able to navigate about 1000 miles using a Movado watch.

I don't know who you are or what you do...

Da Kine... Trust me. Mr. Gary Davis is very well qualified as a
commentator on this news group. Refer to the following URL:

http://www.navy.forces.gc.ca/oriole/...mandteam_e.asp

Best regards

Bill

Well, it should still work as a receiver, anyway.

Terry K

On 6 Mar 2006 20:20:24 -0800, "purple_stars"
wrote:

snipity-snip

RDF might be fun to play around with out in the deep blue.

Correct me if I'm wrong, but don't radio waves travel in great
circles? If so it might be fun working the great circles out in
conjunction with your RDF fixes.
Just a thought.
Mark E. Williams

On Wed, 08 Mar 2006 17:54:51 -0600, Maynard G. Krebbs
wrote:

RDF might be fun to play around with out in the deep blue.

Correct me if I'm wrong, but don't radio waves travel in great
circles? If so it might be fun working the great circles out in
conjunction with your RDF fixes.

The vast majority of RDF fixes are done at ranges of less than 50
miles or so. They become increasingly unreliable as the distance
increases for a variety of reasons. When RDFs were still popular they
were frequently used at ranges of just a few miles to home in on a
breakwater or harbor entrance in the fog.

On 8 Mar 2006 15:25:57 -0800, "Terry K" wrote:

Well, it should still work as a receiver, anyway.

True, and they are big enough that it is not likely to get lost or
misplaced. :-)

Maynard G. Krebbs wrote in
:

RDF might be fun to play around with out in the deep blue.

Correct me if I'm wrong, but don't radio waves travel in great
circles? If so it might be fun working the great circles out in
conjunction with your RDF fixes.
Just a thought.
Mark E. Williams



RDF is great as long as there is NO DRIFT, water current or wind drift.

If you don't learn to take that into account and just follow the RDF to the
station, you end up in this big spiral to the target, the long way around!

GPS, of course, doesn't suffer these 1930's problems.

Larry wrote:
Maynard G. Krebbs wrote in
:


RDF might be fun to play around with out in the deep blue.

Correct me if I'm wrong, but don't radio waves travel in great
circles? If so it might be fun working the great circles out in
conjunction with your RDF fixes.
Just a thought.
Mark E. Williams




RDF is great as long as there is NO DRIFT, water current or wind drift.

If you don't learn to take that into account and just follow the RDF to the
station, you end up in this big spiral to the target, the long way around!

GPS, of course, doesn't suffer these 1930's problems.

I understand one of the problems with RDF in the English Channel was
collisions with the beacon ships. Apparently, because RDF doesn't give
ranges, it is always critical to keep the radio beacon of the light ship
on one bow or the other when in fog!

Larry wrote:
....

RDF is great as long as there is NO DRIFT, water current or wind drift.

If you don't learn to take that into account and just follow the RDF to the
station, you end up in this big spiral to the target, the long way around!


The same will happen with a GPS, unless you know how to use cross
track error. And its certainly better than simply following a compass
bearing.

Anyone capable of using RDF would also know how to use a compass, and
understand the meaning of the changing bearing. Today's GPS user
doesn't necessarily have these skills.

GPS, of course, doesn't suffer these 1930's problems.

1930's??? Most boaters couldn't afford Loran until the late 1980's.
And small, waterproof GPS only became available until about 10 years
ago. You sound like a n00b that took his "safe boating class" from
the jetski salesman last weekend.