Several students of DeVry Institute of Technology in Calgary, Alberta, Canada did just that with
four GPS receivers, a computer, and some specialized software. Four inch accuracy. **No kidding.**
I don't know if they had DGPS units for the experiment. The experiment snowballed from an earlier
experiement that won them some sort of international championship in 2001 when they got an
automated, computer guided model helicopter to lift off, fly 3 meters and hover over a four inch
target, hook onto it and then fly back and land. No manual control what-so-ever. Pretty neat if
you ask me! (But I heard they had to drive at only a walking pace).

"Jack Dale" wrote:
How many out there are prepared to drive their car using GPS only?

On Tue, 18 Jan 2005 05:13:19 GMT, "Richard P." wrote:

Several students of DeVry Institute of Technology in Calgary, Alberta, Canada did just that with
four GPS receivers, a computer, and some specialized software. Four inch accuracy. **No kidding.**
I don't know if they had DGPS units for the experiment. The experiment snowballed from an earlier
experiement that won them some sort of international championship in 2001 when they got an
automated, computer guided model helicopter to lift off, fly 3 meters and hover over a four inch
target, hook onto it and then fly back and land. No manual control what-so-ever. Pretty neat if
you ask me! (But I heard they had to drive at only a walking pace).

"Jack Dale" wrote:
How many out there are prepared to drive their car using GPS only?

I live in Calgary. I hope they send out a notice to drivers when they
do it.

My lack of faith in GPS was reinforced when the chartplotter showed
my boat on land while safely anchored stern-to in Princess Bay on
Wallace Island.

On the other hand, I did navigate through the rocks in Race Passage in
last year's Swiftsure using GPS. I had a paper chart in front of me
while I did it.

Jack

Jack Dale wrote:


My lack of faith in GPS was reinforced when the chartplotter showed
my boat on land while safely anchored stern-to in Princess Bay on
Wallace Island.

On the other hand, I did navigate through the rocks in Race Passage in
last year's Swiftsure using GPS. I had a paper chart in front of me
while I did it.

Jack



This is the problem/situation that many are noting, especially those
using chart plotters.
During most piloting exercises where we're underway, many minor
discrepancies between the chart plotter position and actual will not be
readily apparent as they are relatively small and due to the fact you
are normally giving a "safe berth" to most points you are passing, of
little consequence.
However, once you are anchored or moored or even working around a tight
docking situation, these discrepancies DO become readily apparent.
In most cases, I'm dealing with chart plotters on different vessels (all
gyro stabilized) that are using same/different/similar electronic
packages and unknown chart data (some charts I know to be older versions).
Depending on the vessel, I've noted errors of from @10' - 100' of a
variable nature (sometimes between trips, sometimes between vessels).
in this particular port. The most obvious being when alongside the dock.
Personally, when piloting, naturally my first choice is eyeball, but if
I have a GPS readout handy to where I'm standing I use it to confirm
speed and get a backup to my sense of set and drift, and where I have a
chart plotter to look at, I glance at it for a "birdseye" view, though I
put more weight on the "birdseye" view from the radar where accuracy is
concerned, as long as the particular radar picture is clear.
Naturally, what I'm discussing is for a particular port. Each port and
set-up will vary/differ .... my main point is that you should use
everything at hand, be aware of possible drawbacks to each and make
maximum use of the positives.

otn

On Tue, 18 Jan 2005 17:59:40 GMT, otnmbrd
wrote:
I've noted errors of from @10' - 100' of a
variable nature (sometimes between trips, sometimes between vessels).
in this particular port. The most obvious being when alongside the dock.

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

There are fixed errors also. I live on the south side of a 120 foot
canal. Four different WAAS GPS units consistently show the boat
docked on the north side. Most likely chart error but who knows?

On Tue, 18 Jan 2005 17:59:40 GMT, otnmbrd
wrote:

Jack Dale wrote:


My lack of faith in GPS was reinforced when the chartplotter showed
my boat on land while safely anchored stern-to in Princess Bay on
Wallace Island.

On the other hand, I did navigate through the rocks in Race Passage in
last year's Swiftsure using GPS. I had a paper chart in front of me
while I did it.

Jack



This is the problem/situation that many are noting, especially those
using chart plotters.
During most piloting exercises where we're underway, many minor
discrepancies between the chart plotter position and actual will not be
readily apparent as they are relatively small and due to the fact you
are normally giving a "safe berth" to most points you are passing, of
little consequence.
However, once you are anchored or moored or even working around a tight
docking situation, these discrepancies DO become readily apparent.
In most cases, I'm dealing with chart plotters on different vessels (all
gyro stabilized) that are using same/different/similar electronic
packages and unknown chart data (some charts I know to be older versions).
Depending on the vessel, I've noted errors of from @10' - 100' of a
variable nature (sometimes between trips, sometimes between vessels).
in this particular port. The most obvious being when alongside the dock.
Personally, when piloting, naturally my first choice is eyeball, but if
I have a GPS readout handy to where I'm standing I use it to confirm
speed and get a backup to my sense of set and drift, and where I have a
chart plotter to look at, I glance at it for a "birdseye" view, though I
put more weight on the "birdseye" view from the radar where accuracy is
concerned, as long as the particular radar picture is clear.
Naturally, what I'm discussing is for a particular port. Each port and
set-up will vary/differ .... my main point is that you should use
everything at hand, be aware of possible drawbacks to each and make
maximum use of the positives.

It would seem interesting to investigate what caused the errors in the
charting systems. My experience with non-charting WAAS receivers is
much tighter. At the slip we have used for the past few years, the GPS
not only tells us we are in our own slip, and not either adjacent, but
whether we are bow or stern in.

You did say the source for chart data was unknown.

I haven't purchased a charting system because I would still have to
keep paper charts even if I did. I am interested to read of your
experiences, and thank everyone for this thread.



Rodney Myrvaagnes NYC J36 Gjo/a


"Be careful. The toe you stepped on yesterday may be connected to the ass you have to kiss today." --Former mayor Ciancia

Rodney Myrvaagnes wrote:


It would seem interesting to investigate what caused the errors in the
charting systems. My experience with non-charting WAAS receivers is
much tighter. At the slip we have used for the past few years, the GPS
not only tells us we are in our own slip, and not either adjacent, but
whether we are bow or stern in.

You did say the source for chart data was unknown.

I haven't purchased a charting system because I would still have to
keep paper charts even if I did. I am interested to read of your
experiences, and thank everyone for this thread.



Rodney Myrvaagnes

I have a strong feeling that much the the information we all gather as
to possible anomalies in GPS fixes versus plotted positions/chart
plotter positions/actual positions will for the most part end up as very
case specific.
We will also need to know who's charts the plotter data is based on
(NOAA/British Admiralty) and is it up to date; who created the plotter
program; are all the components matched and compatible; is the error
consistent; etc. (much of this need some tech types to rule out or
confirm system problems versus charting problems).
Nowadays, all of what I'm seeing is very Port specific and not of much
help to the average boater, other than to say the possibilities exist.
I do note that I've seen a great improvement over the years that I've
been using chart plotters for this port, to the point that in some cases
I consider the units "right on", G with reservations.
Again, and as always on this subject ..... never rely exclusively on one
system, especially in confined waters.

otn

On Wed, 19 Jan 2005 17:24:31 GMT, otnmbrd
wrote:

Rodney Myrvaagnes wrote:


It would seem interesting to investigate what caused the errors in the
charting systems. My experience with non-charting WAAS receivers is
much tighter. At the slip we have used for the past few years, the GPS
not only tells us we are in our own slip, and not either adjacent, but
whether we are bow or stern in.

You did say the source for chart data was unknown.

I haven't purchased a charting system because I would still have to
keep paper charts even if I did. I am interested to read of your
experiences, and thank everyone for this thread.



Rodney Myrvaagnes

I have a strong feeling that much the the information we all gather as
to possible anomalies in GPS fixes versus plotted positions/chart
plotter positions/actual positions will for the most part end up as very
case specific.
We will also need to know who's charts the plotter data is based on
(NOAA/British Admiralty) and is it up to date; who created the plotter
program; are all the components matched and compatible; is the error
consistent; etc. (much of this need some tech types to rule out or
confirm system problems versus charting problems).
Nowadays, all of what I'm seeing is very Port specific and not of much
help to the average boater, other than to say the possibilities exist.
I do note that I've seen a great improvement over the years that I've
been using chart plotters for this port, to the point that in some cases
I consider the units "right on", G with reservations.
Again, and as always on this subject ..... never rely exclusively on one
system, especially in confined waters.

otn
In this connection I should say where I got these tight results. It is
a marina just south of the Holland Tunnel on the NJ side of the North
(Hudson) River. The chart survey is new, since it shows the floating
docks that were only built in 1989.

I use charts in Maine that use 18th and 19th Century surveys, and will
probably never get redone. The situation there is not the same as in
NY Harbor, where many charts are sold every year.

In Maine, I use the GPS the way I formerly used Loran C, for
repeatibility, in places I have already visited.



Rodney Myrvaagnes NYC J36 Gjo/a


"Be careful. The toe you stepped on yesterday may be connected to the ass you have to kiss today." --Former mayor Ciancia