You phrased the question badly. If everything is displaced along with the
rock it is rather straight forward to correct if you know of the error. If
a rock is mischarted or uncharted you are correct. I think mischarted
rocks are very rare. Mostly placed badly with everything else or missed
completely.

On the west coast we often deal with rapidly rising land masses...often at
angles of more than 60 degrees with reference to the horizontal. You better
be going real slow if you expect to get a depth sounder alert.

This is actually a place where the GPS operator is at a disadvantage. A
piloting operation is relative to local landmarks while GPS is
absolute...so if the GPS guy is not aware of the error he has a problem in
comparison to a piloting operator.

On the other side of the equation in is reasonably easy for a gps operator
to maintain someting close to optimal clearance of hard stuff. It is a
complex and difficult task for a pilotage operator to do the same.

Jim Donohue

"Dave" wrote in message
...
On Fri, 21 Jan 2005 08:15:10 -0800, "Jim Donohue"

said:

In many places you use the numbers from last time. Many of the numbers
are
published in guides or privately. You can also set up the course to
minimize exposure.

In general the errors are area wide. You work out the correction from
known
objects. You use radar and the bottom to assure yourself you did it
correctly. Go slow when in doubt.

Not responsive to the question. The question was:

OK, how is that GPS going to help you avoid hitting that rock that's
shown
in the wrong place on the chart?

The responsive answer would be that a GPS is as likely to send you into
that
uncharted rock as any other method, but there are other ways to avoid the
rock that's somewhere other than where the chart shows it, like a depth
sounder, and plotting a course well away from known rocks.

On 21 Jan 2005 17:12:08 -0600, Dave wrote:

Yes. I well remember coming back from Cuttyhunk to Pt. Judith in a fog using
RDF. Sure was glad to see the openings in the harbor of refuge breakwaters
appear out of the fog.

==========================

Ahhh yes, another sea story from the past. We did the same trip under
similar circumstances back in the early 80s, probably when we still
had the Westerly 28 and the kids were young. The closer we got to Pt
Judith, the foggier it got until we were down to total pea soup
conditions. Eventualy we could hear the surf on the breakwater and
see the spray flying. Following the breakwater around to the western
entrance, we DR'd our way to the channel buoys and upstream, where
the fog eventually eased up a bit. We found a place to dock on the
western side and shared a small dock with another sail boat. Talking
with them later in the evening we learned they had been there 5 days
waiting for the fog to lift! Next morning they were still there
waiting. We proceeded on down to the breakwater, once again
navigating in heavy fog, while dodging incoming ferrys and fishing
boats. Several miles from the breakwater the fog lifted again and it
was clear sailing all the way back into Long Island Sound. One of our
family jokes is speculating on whether or not the other boat is still
in Pt Judith waiting for the fog to lift.

Bruce in Alaska wrote:



I would like to add a simple note here.

OTN talks about using Radar and the Mark One Eyeball to get position
fixes while navigating in coastal and inshore waters. Ok, that is common
practice, and has been for MANY years.

Now consider the accuracy of those fixes, as compared with the accuracy
of an Electronic Position Fixing Device.

BG Dang! I gotta find this place you guys are navigating through, that
requires instant position data, within a few inches.....


Mark One Eyeball.... Taking a sight with binocs even over a compass card
will usually get a line within a degree or two, IF the guy is really
good at it or is using one of those old WWII TBT's... Ok, now figure
that your going to have to do that on at least two bearings, and better
yet, three or four. Ok, now you have to go plot those bearings on the
chart using the reverse bearing from the marker you sited on, and then
figuring in the time difference between the bearings, and the speed of
advance, of the vessel, and you don't get a REAL FIX, but an AREA of
FIX that IS "Orders of Magnitude" bigger than the REALTIME GPS Fix.

First off, the "Mark One Eyeball" method of navigation, can be many
things. What you describe above, is just one of them. The accuracy of
that same method can vary, from, exceeding GPS, to useless, but on
average,will be well within the needed parameters to safely navigate an
area under normal conditions.
Needless to say, this method tends to suck in restricted visibility.
With all due respect Bruce, it's obvious from your above that you are
not all that familiar with the method you are discussing.


Radar..... Same thing here, except that your bearing will tend to be
better, depending on the Horozontal Beamwidth of the antenna, and the
distance, and area of the target which the bearing is to. Again, the
AREA of the FIX will be smaller for the radar because the time to get
the bearins, (two or more) will be shorter, but the plotting times and
the speed of advance will be the same. Again the Area of fix will
be "Orders of Magnitude" larger than the REALTIME GPS Fix.

Here, you are using only one of the methods available to you (in fact,
the time consuming one). Sorry Bruce, but like Jim, your radar
navigation needs work, also. Stand beside me under most coastal
navigation areas in Alaska, take a reading on a GPS fix, at the same
time I take a range and bearing via radar ... betcha I beat you plotting
said fix and the only discrepancy between the two positions will revolve
around how sharp my pencil was (unless of course the chart is in error,
in which case my position is more apt to keep us out of trouble).
BTW, forget the "speed of advance" junk .... it's a lame argument at the
speeds we are talking about for most cruisers.... unless, of course,
they've screwed up and gotten too close to a nav hazard, to begin with.


GPS Fix..... even with out WAAS, this should be in the 30 foot centered
circle, and the speed of advance isn't even a problem due to the small
amount of advance in the one second cycle times of GPS Calulations.
The same can be said for LORAN-C with modern day Receivers, that have
builtin Lat/LONG Calculators, especially if the route has been run
before, and Know Anomalies in the TD's are already accounted for.

If, for the most part, your navigation requires you to be within a 30'
centered circle, then I have to question your "route planning". Granted,
there are times when you need precise distance information and you are
navigating in narrow areas such a marina's and harbors where you have to
work between docks, but in those areas, I'll take radar every time,
because it doesn't care if the charted positions are correct.



Now all the above really is mostly not a GIANT Issue at 7 - 12 Knots,
as there is always enough time to figure this all out. However, I defy
anyone to show me how anything but a Very GOOD GPS Based Navigation
System can be used on a Fast Ferry doing 35+ Knots inside Boston Harbour.
Speed KILLS, and the faster these guys go, the faster one of them is
going to run the rest of us over, because the navigator isn't watching
where he is going, because he is busy PLOTTING his position.

Explain to me why this isn't a problem......


Sorry, haven't ridden any fast ferries in Boston. Rode the ones from
Hyannis to Nantucket. From what I saw, most "general" navigation was
done by "eyeball" and "radar"..... Why?....For those running a familiar
route, it's faster and generally, more "spatial awareness" accurate for
the operator. When a chart plotter is available, it's a fantastic third
tool that frequently changes ranking in importance over the radar and
eyeball..... so, in answer to your question, it IS a problem that
various operators need address, though a simple GPS without a chart
plotter is NOT the solution.


otn

Jim Donohue wrote:
SNIP

On the other side of the equation in is reasonably easy for a gps operator
to maintain someting close to optimal clearance of hard stuff. It is a
complex and difficult task for a pilotage operator to do the same.

Jim Donohue

LOL Only part I think needs clarification.
In coastal navigation (especially on much of the US West Coast), if the
operator knows what he/she is doing, it is neither a complex or
difficult task to maintain optimal clearance of hard stuff, under normal
"piloting" conditions.

otn

And you mislead outrageously. It is of course quite simple on the west
coast. It is the nature of the coast. However we are dealing with a
"otnmbrd" wrote in message
nk.net...
Jim Donohue wrote:
SNIP

On the other side of the equation in is reasonably easy for a gps
operator to maintain someting close to optimal clearance of hard stuff.
It is a complex and difficult task for a pilotage operator to do the
same.

Jim Donohue

LOL Only part I think needs clarification.
In coastal navigation (especially on much of the US West Coast), if the
operator knows what he/she is doing, it is neither a complex or difficult
task to maintain optimal clearance of hard stuff, under normal "piloting"
conditions.

otn


While I do agree that the west is easier than the east one must still
remember that
piloting in navigation involves frequent or continuous determination of
positon or a line of positon relative to geograhic points, and usually
requiring need for close attention to the vessel's draft with respect to the
depth of water. Iti is practiced in the vicinity of land, dangers, etc. and
requires good judgement and almost constant attention and alertness on the
part of the navigator.

Which part don't you understand otn?

Jim

I'm a bit baffled by those who say you need nothing more than
GPS.
Is GPS accurate? Of course it is. But make sure the GPS is
set to the earth model the chart is. Oh, and make sure you
never transpose numbers when entering waypoint data. One
more small item...check the route to make sure there are no
rocks/reefs in the way..the GPS will cheerfully run you aground.
But you've already thought of those factors.
Are DR nav methods, charts, hand bearings, etc. less accruate
than GPS? Of course they are.
Should one rely ONLY on GPS and chart plotters?
If the answer is "yes", then that inplies you believe the electronics
will never fail. And the IRS will never audit you..right?
Is there something *wrong* with suggesting/teaching mulitple methods
of navigation? I don't think GPS/radar have feelings...it won't mind
if you confirm position by other means.
Since I'm in a cranky mood, I'll tell you that the biggest risk to a boat
is not deploying the Mark One Eyeball in close waters.
For example, I've told students
over and over again to do something as simple as looking behind
them once in awhile when in the islands. But no, they look ahead for
the waypoint coming up. Imagine their surprise when that big ferry or
freighter toots it's horn a 1/4 mile aft. Happens a lot in these waters.
Norm B

Jim Donohue wrote:
And you mislead outrageously. It is of course quite simple on the west
coast. It is the nature of the coast. However we are dealing with a

Nothing misleading.... mayhaps beyond your comprehension?




While I do agree that the west is easier than the east one must still
remember that
piloting in navigation involves frequent or continuous determination of
positon or a line of positon relative to geograhic points, and usually
requiring need for close attention to the vessel's draft with respect to the
depth of water. Iti is practiced in the vicinity of land, dangers, etc. and
requires good judgement and almost constant attention and alertness on the
part of the navigator.

Which part don't you understand otn?

I understand it all quite well.... which part don't you understand?
It doesn't matter what method you are using to determine your position
under piloting conditions.
The point is, (East coast, Gulf coast, West coast... I've done them all)
that piloting, using eyeball or radar methods, is NOT necessarily all
that more complex or difficult a problem to remain at optimal clearance
to the hard stuff compared to GPS.
All your arguments tend to do, is confirm that your piloting skills are
limited, your radar skills are limited, your celestial skills are
limited, since you keep looking for excuses to make GPS your sole source
of navigation.
Truth be known, your 25 years sailing and 12,000 miles coastal
navigation is great and beyond what many have done, but obviously, like
me, you're still learning, but I'm afraid you're not grasping many of
the lessons.

otn

On Fri, 21 Jan 2005 20:08:04 GMT, Bruce in Alaska
wrote:

In article et,
otnmbrd wrote:

Jim Donohue wrote:



Why with professional luddites like you and your ilk I am required for
progress otn.

As stated, "you just don't get it". In truth, I'm a prolific user of
GPS, both the basic readout and connected to a chart plotter, making use
of all the information it supplies.
However, especially in the coastal waters I mainly traverse nowadays,
it's NEVER my sole source of position information and in fact, plotting
a GPS position isn't all that much quicker or necessarily as accurate as
a simple radar range and bearing, or eyeball fix.


The aside points out that the real amateur sailor with sufficient skill to
cross oceans uses GPS otn...and have a likely non working celestial
capability. It is in no way an excuse of any type...merely an observation
on how life actually is. You likely don't like it otn but you really don't
get a vote.

You use your survey as an EXCUSE for not learning or using celestial.
G By "non working" I assume you mean they have the ability but don't
use it. That's their choice, just like it's the choice of many ship
Masters making ocean crossings to require their people to occasionally
take celestial fixes and when in sight of land or radar range, to take
visual fixes as well as radar fixes and compare them to the GPS.
I also note that in another reply, you are still not comfortable using
radar for navigation.... that's too bad.... you're missing out on a
great tool.

otn


I would like to add a simple note here.

OTN talks about using Radar and the Mark One Eyeball to get position
fixes while navigating in coastal and inshore waters. Ok, that is common
practice, and has been for MANY years.

Now consider the accuracy of those fixes, as compared with the accuracy
of an Electronic Position Fixing Device.

Mark One Eyeball.... Taking a sight with binocs even over a compass card
will usually get a line within a degree or two, IF the guy is really
good at it or is using one of those old WWII TBT's... Ok, now figure
that your going to have to do that on at least two bearings, and better
yet, three or four. Ok, now you have to go plot those bearings on the
chart using the reverse bearing from the marker you sited on, and then
figuring in the time difference between the bearings, and the speed of
advance, of the vessel, and you don't get a REAL FIX, but an AREA of
FIX that IS "Orders of Magnitude" bigger than the REALTIME GPS Fix.

Radar..... Same thing here, except that your bearing will tend to be
better, depending on the Horozontal Beamwidth of the antenna, and the
distance, and area of the target which the bearing is to. Again, the
AREA of the FIX will be smaller for the radar because the time to get
the bearins, (two or more) will be shorter, but the plotting times and
the speed of advance will be the same. Again the Area of fix will
be "Orders of Magnitude" larger than the REALTIME GPS Fix.

GPS Fix..... even with out WAAS, this should be in the 30 foot centered
circle, and the speed of advance isn't even a problem due to the small
amount of advance in the one second cycle times of GPS Calulations.
The same can be said for LORAN-C with modern day Receivers, that have
builtin Lat/LONG Calculators, especially if the route has been run
before, and Know Anomalies in the TD's are already accounted for.

Now all the above really is mostly not a GIANT Issue at 7 - 12 Knots,
as there is always enough time to figure this all out. However, I defy
anyone to show me how anything but a Very GOOD GPS Based Navigation
System can be used on a Fast Ferry doing 35+ Knots inside Boston Harbour.
Speed KILLS, and the faster these guys go, the faster one of them is
going to run the rest of us over, because the navigator isn't watching
where he is going, because he is busy PLOTTING his position.

Explain to me why this isn't a problem......

The ferry service between Stockhom and Helsinki was dependent on GPS
with its own diferential setup back in the 1980s, years before the
USCG had differential beacons, never mind WAAS.

They were threading a lot of islands really fast in all visibilities,
including zero. And their schedules were much faster than before GPS.

Differential at that time was crucial for cancelling the effects of
SA. Of course, they could survey the route themselves and verify the
correspondence between GPS and chart.

And, their differential system would have alarmed immediately on any
GPS failure.


Rodney Myrvaagnes J36 Gjo/a

For your upscale SUV: Dingle-balls hand knit of natural Icelandic yarn

Good Morning Roger!
I just read your thread. I was moved by it. I am a neophyte sailor who has
been avidly sailing and living aboard for over six years on a small racing
sloop (7.7m). I conclude from your edress that you're in New England.
I know it won't be possible for me to come to you, so would you consider
passing on " that something rich and rewarding" to someone eager to learn it
as opposed to having it passing "from my life" and being lost forever.
Although I have and use the new GPS technology I am eager to learn the old
ways. My problem is I can't afford the schools for celestial navigation etc.
If interested would you be interested in a "distance learning program" with
me. Then perhaps in the future we can establish a time when I can come to
your location over a long weekend or personal vacation to test and apply
what I've learned. Maybe this is a crazy idea to you, but I hope you will
find someone to whom you can "pass down'' this knowledge and experience so
that it can be perpetuated instead of lost.

Rico
S/V OSAZZE
"Roger Long" wrote in message
...
The post about taking your charts with a grain of salt and using all
available information brings up the conundrum I'm facing as I return
to sailing after nearly 20 years.

Most of my command time was in simple, traditional, boats. The most
complex instrument on board was my usually watch. I didn't even have a
depth sounder or speedometer and navigated clock and compass exactly
as was done 100 years ago. Since I sailed in Maine, I saw a lot of fog
and made a lot of long runs this way.

Never in a boat have I felt more aware and in touch with my
surroundings then when enveloped in that gray cocoon with buoys and
ledges occasionally moving through it, usually right on schedule. The
faint sound of a wave on rock, the darkening of the fog where a
headland blocked the light, a change in wave patterns as I passed a
gap in a protecting chain of islands or ledges, all helped confirm
that my chart work was right.

Some of the later boats I chartered had Loran but I never turned it
on. I didn't want to be distracted by learning it and using the old
ways was a big part of the enjoyment of cruising. I used (and taught
when I was a piloting instructor) very simple methods that would be
less likely to let me down when tired or busy. Instead of speed and
distance calculations, I would just set my dividers to the boat's
speed on the scale and then do everything in time.

On one of my last charters, a hurricane threatened. We were way
downeast and the owner insisted that we had to get sixty miles back to
his mooring in dense fog instead of tucking the boat into a hole and
riding it out. It was one of the thickest fogs I have ever seen. We
ran through most of Fox Island Thoroughfare without seeing either
shore. It was a memorable day.


I learned how to fly airplanes a few years later and that put
navigation in a whole new light. The plane had Loran and GPS but I
refused to turn them on for the first three years so that I would
develop the map and eyeball skills and a feel for the distances and
speed. Now I use the magic boxes all the time but, in some ways, my
situational awareness is less. I track a position that I can transfer
to the paper map it the power fails but it is different. I used to be
flying over the land and identified fixes below. Now I am flying over
the map. You get lazy fast, especially with all the other things to
attend to in an airplane.

Now that I am about to return to boat piloting, I'm unsure about the
place of GPS in my life. The old ways were a big part of cruising for
me. Ride a cable car up a mountain in Switzerland and you may see
people with ropes hanging by their fingernails trying to get the same
place you are going. The rational is similar. I'd also like my video
gaming kids to learn what the human mind can accomplish without the
aid of a microprocessor.

But, is it responsible? It certainly won't be seen as such if I ever
hit anything. On the other hand, I know of many aircraft accidents
that were clearly caused by the pilot trying to use the box instead of
his mind. I always used to know where I was. I'm not sure narrowing it
down with an electronic cursor will significantly increase my safety
in most circumstances.

The strongest rational I can see for relating my place in life to
invisible satellites instead of the landscape I can see around me is
backup for my macroprocessor. If I should fall overboard or become
incapacitated, the kids can either tell the Coast Guard, "We're right
here", or follow the cursor home. I'd like to think I could teach them
to do the same thing the old way but, face it, they know about GPS,
they aren't going to be very interested in learning that, "other
stuff".

I like gadgets though. I have an old aviation GPS that will give me
latitude, longitude, and waypoints. I can't knowingly leave it ashore.
I'll have to buy a marine unit for my new job as Harbormaster. I won't
leave that behind either. Once I turn them on, I know I'll be hooked
and something very rich and rewarding will have passed from my life
forever.


--

Roger Long

Well, I'm touched by your comments.

However, there is nothing special about my knowledge. It's just the
basics of coastal piloting and the foundation on which you should
build your use of more advanced methods and tools.

My original comment was that, when forced to rely on these methods
alone because of economics and the availability of equipment at the
time, I found myself forced into a heightened awareness of my
surroundings and enjoying the simplicity. It's much like how a
backpacker experiences his environment differently than someone who is
driving through it. Just as there are times and places you shouldn't
be walking, there are times and places that it would be foolish not to
use GPS and other such tools now that they are universally available.

I was never actually taught any of this. I just read about it and
really paid attention when I first started going out in boats. You can
do the same although learning from people who know more is never
wasted.

Finally, I know next to nothing about celestial. I'm strictly a
coastal sailor. My big boat ocean time has always been as crew.

I'm not in a position to take time to teach you anything personally
and, as I said, it's no more that what a good piloting teacher would
teach you first. The key is to navigate constantly, even when there is
no question about your position. Read what you can, talk to everyone
you can, and just sail in an alert fashion trying different things and
paying attention to every clue you can. You should do fine.