Jim Donohue wrote:
"Jeff Morris" wrote in message
...

Jim Donohue wrote:

Anyone who has been on a boat knows that a GPS *DOES NOT* for all
practical purposes work all of the time. I've had a GPS fail several
times, I've seen charting inaccuracies a number of times. Similar things
have happened to almost every cruiser I know.


You lead an unlucky life. I have never seen a significant outage of the
GPS. I follow the tech literature on the subject. Aside from deliberate
military actions the outages are very few, far between, and limited in time
duration. As I said I have never seen one.

You mean, other that the outages that have happened, there have been none?

I'll admit the system has been pretty stable but individual satellites
are taken down which causes minor hiccups. Several weeks ago, my wife's
car GPS was off by a quarter mile for about 5 minutes - I have no idea
what the cause was, but it could have been a problem on a boat.


It is of course possible that you have a source of interference on your
boat. That does happen. It is one of the reasons that multiple GPSs are
sensible. Different devices have different weaknesses. I am sure there
are also some specific locations that have a multi-path problem. Again
though few and far between. GPS ain't perfect but it is very close. Done
with redundant instruments on the open sea it is, for all practical
purposes, perfect.

The problem that has bit me a few times is that I use a handheld which
is connected to its cable every time I use the boat. If the power
connection isn't solid, it can fall back to battery power, and then shut
off a few hours later. I keep spare cables and batteries, but when it
happens, I'm down for a few minutes.

And although I often have a chart cartridge, I've found occasional
"dropouts" in the coverage - rather disconcerting when you're in a
tricky section of the ICW and the chart screen suddenly goes blank.

On my previous boat (Nonsuch 30) I would lose signal sometimes. I
assumed it was from the wishbone boom, but others claimed the antennae
was too low and the signal was blocked by crew members; perhaps both
causes were factors.

I've never been hit by lightning, by I know many others that have, and
the GPS is frequently a victim. I've also heard of GPS's damaged by
power spikes. Actually, the first time I took a GPS on a trip its menu
button was damaged so it was virtually useless.

Having a spare GPS, and batteries, cables, etc. on board is useful and
prudent, but it doesn't help when you lose the primary in a tricky
situation.

While these problems are infrequent, and often "operator error" it does
not mean they don't happen. And having a strategy to cope, such as
carrying a redundant GPS doesn't help you for the time it takes find it
and fire it up.



The present cruiser population is certainly and effectively completely
dependent on GPS for off shore navigation. At this point I don't think
there are many exceptions left. I have not come across a report of a
significant problem with that in a long time.

What's your point? The vast majority of boaters don't go offshore. And
obviously, piloting techniques are not commonly used off shore. You
keep trying to equate piloting with celestial; they're are not the same
thing.


Charting inaccuracies are chart problems very close to completely. Without
gps they are hard to detect. The ones on the West coast of Mexico however
are detectible with a good LORAN.

Without GPS the charting inaccuracies would not be as important. As I
mentioned before, I watched a trawler run aground because they trusted
the GPS and didn't watch the depth.





None of these incidents were a major problem for me because I was using
other techniques and was able to recognize the situation and compensate.

The issue here is not which technique is the most accurate, or which
should be used to the exclusion of the other. Continuing to cast it in
these terms make you look like a jaxian fool.


One uses all reasonable methods available. The first and primary of these
is GPS. Your inablity to understand this simple statement is almost jaxian.

The question isn't what should be used first; the question is what
should be taught first. Your inability to understand that is beyond jaxian.

Teaching someone GPS before basic piloting is like teaching children how
to use a calculator before teaching them the addition table.





The issue is that you claimed it was foolish to teach someone basic
piloting, even when the person was eager to learn. This attitude marks
you as a complete fool, Jim. I hope I never meet one of your students on
the water.


No my argument was that basic navigation...not piloting...was better taught
with GPS as the primary technique. It was in response to an individual
teaching basic navigation with electronic aids removed.

Actually, the case was that someone was learning how to do LOP's and DR
and wasn't interested in LORAN. You called this "utter nonsense." I
call your attitude "sheer stupidity."


It is even possible
that the individual involved and I would end at the same end point. Just
different routings.

It is remotely possible, but someone who learns how to use a GPS first
is rather unlikely to then learn basic piloting. And this is the
essential point of my argument. Anyone can teach them self how to use a
GPS; learning piloting usually takes instruction and practice. If I
only have a student for a few hours, I'd rather spend time on something
that's harder to learn, and just as important. Most of the concepts of
piloting relate to GPS usage, so nothing is wasted.


And you again utterly misstate my position. GPS is the first skill
taught...it should be the centerpiece of the navigation system. Then
others. Certainly even the dullest of students can learn to check a
chart position via eyeball or radar.

Are you daft, man? Are you claiming now that piloting need not be taught
because "even the dullest" can do it without training? And radar too?
Bizarre, considering you've confessed to have weak radar skills!


Listen carefully. Pilotage is important. One teaches navigation with the
GPS first.

One person might do that, the rest of us will teach properly, thank you.

The first portion of that instruction is the use of charts.

agreed.

A
current student however should learn with the GPS positon centric techniques
rather than the LOP techniques of conventional DR.

DR doesn't involve LOPs. Its clear your understanding in this area is weak.

Yes eventually these get
taught also...but secondary to what is the real world.

Eventually? Yea, right.



You asserted that learning LOP's and DR was "utter nonsense." I think no
one should be trusted with a GPS until the learn these basics.


Uhhh where did it state that learning LOPs and DR was "utter nonsense"? I
think I made such a comment about teaching a student navigation with such
techniques emphasized to the exclusion of electronic navigation. Still do.

Perhaps you should re-read your fist post in this thread. Dave said his
daughter was enjoying learning LOP's and DR, and wasn't interested in
the Loran. Your response was "Ohh stop...what utter nonsense." You
went on to spew more silliness which only served to make you feel
important and make everyone else think you're a fool.

Nowhere was it mentioned that Dave's daughter would not go on to learn
other techniques, or that she was even destined to be a boat's
navigator. It was only stated that she enjoyed learning basic piloting.

Frankly criticizing anyone for wanting to learn almost anything is a
mark of a very small mind.



You correctly point out that it will be difficult to teach DR/LOP after one
learns electronic navigation. That is because it is difficult to convince
the student that sufficient value exists in such techniques. You deal with
this value problem by teaching DR/LOP first.

There's a bit more to it, but OK ...

I claim simple that this in
no way prevents the knowledge of DR/LOP going away real fast. I think we
need to develop that set of DR/LOP skills that will actually stick after
electronic navigation is learned. If we can't develop such a set and
convince the newby of value then the outcome is the same.

The way to do this is to actively practice "manual techniques" even
while using a GPS. I've never known someone who learned GPS first who
did this. However, once you have actually navigated by LOP's, or
following depth contours, or watching "danger bearings," it starts to
become automatic. When I see a buoy line up with a point of land, I
mentally follow the line on the chart and check the depth I should be
in. It only takes a second, but would someone who had never done that
"for real" bother to do it?


I stress the electronic navigation first because I think it more important
they do that well than that they master an initial set of techniques they
will abandon upon learning the electronic version. First good at the
primary system then good at the secondaries.

Too bad the world doesn't work this way. We could teach calculators in
the third grade because the kids could be trusted to learn long division
later.

I introduce VOR/DME and RDF merely to demonstrate that we really don't
propose to teach all available navigation techniques...only those that we
believe useful and reasonable.

There are lots of techniques that are arcane or obsolete. They may be
of interest to the advanced navigator or hobbies, but they are in a
different category from piloting, especially when the equipment isn't
often carried on board.



The NTSB study blamed several "probable causes:" over reliance on GPS, and
lack of training of the officers, and the failure to recognize the problem
from other cues. This is a perfect example of problem with your approach.
Claiming that your strategy works, but in this case they were incompetent
is foolish.

http://www.ntsb.gov/publictn/1997/MAR9701.pdf


I am reasonably familiar with the report. Find for me any mention of over
reliance on GPS. It does find fault with over reliance on the automatic
features of integrated bridge systems.

Calling it a "system" was a euphemism. It was a GPS attached to an
autopilot. They ignored the depth sounder, the radar, and visual cues.
Actually, the same thing could have happened to most anyone with an
Autohelm and a Garmin, except the the Autohelm (now Raymarine) gives a
better indication of faulty input.

It also discusses flaws in the
design of such systems. I agree that total reliance on a single GPS is not
wise. I generally run three...and two are active in the process to try to
avoid the entry errors that I believe are the worst problems with GPS
navigation. When the europeans get their system operative or the Russians
complete theirs I will almost certainly run one GPS off another system. I
will also use other inputs like depthsounders and radar to help prevent
errors.

So you turn on 3 gps's for a day sail? I think you'd be better served
by brushing up on more basic skills.