Autopilots

Time for a yearly update. I had a Bombardier Utopia - an 18'
jet-powered runabout that I added an autopilot to, but while it did work
at higher speeds, it failed miserably for trolling and fishing in
general. Last year I sold it and bought a center console Cobia, a 21'
with a 150 hp Yamaha outboard. I added a 15 hp (smallest I could get
without ordering) Suzuki outboard to use as a trolling motor. It is
tied, mechanically, to the larger Yamaha and sips fuel from the same
large tank. It works pretty well, and steers a straight course with no
hands on the wheel.

Still, I'd like to add an autopilot IF (and only if) it can operate at
trolling speeds (about 1 knot or 1.5 mph). ComNav makes a few units
which look like they'd work, but I'd like to hear that from someone
other than the manufacturer or salesman, preferably someone who owns
one. The boat is equipped with a Garmin 540 combination fishfinder/GPS
chartplotter which issues NMEA sentences.
--

Larry
rapp at lmr dot com

"Larry" wrote in message
...
Time for a yearly update. I had a Bombardier Utopia - an 18' jet-powered
runabout that I added an autopilot to, but while it did work at higher
speeds, it failed miserably for trolling and fishing in general. Last
year I sold it and bought a center console Cobia, a 21' with a 150 hp
Yamaha outboard. I added a 15 hp (smallest I could get without ordering)
Suzuki outboard to use as a trolling motor. It is tied, mechanically, to
the larger Yamaha and sips fuel from the same large tank. It works pretty
well, and steers a straight course with no hands on the wheel.

Still, I'd like to add an autopilot IF (and only if) it can operate at
trolling speeds (about 1 knot or 1.5 mph). ComNav makes a few units which
look like they'd work, but I'd like to hear that from someone other than
the manufacturer or salesman, preferably someone who owns one. The boat
is equipped with a Garmin 540 combination fishfinder/GPS chartplotter
which issues NMEA sentences.
--

You need an autopilot where you can alter the amount of response to a given
course deviation.
At trolling speeds you need much more rudder angle to correct a deviation
than you would at higher speed.
However, if you are trolling rather than maintaining course to a destination
you ought to be able to accept a greater amount of yawing about the set
course anyway.

Just what the world needs - another autopilot jetboat jerk who hasn't a clue
as to how to safely operate a boat blasting around the water becoming a big
nuisance and even larger menace to all concerned.

Take your autopilot, and overgrown Jetski for that matter, and shove it up
your ass!

--
Gregory Hall


"Larry" wrote in message
...
Time for a yearly update. I had a Bombardier Utopia - an 18' jet-powered
runabout that I added an autopilot to, but while it did work at higher
speeds, it failed miserably for trolling and fishing in general. Last
year I sold it and bought a center console Cobia, a 21' with a 150 hp
Yamaha outboard. I added a 15 hp (smallest I could get without ordering)
Suzuki outboard to use as a trolling motor. It is tied, mechanically, to
the larger Yamaha and sips fuel from the same large tank. It works pretty
well, and steers a straight course with no hands on the wheel.

Still, I'd like to add an autopilot IF (and only if) it can operate at
trolling speeds (about 1 knot or 1.5 mph). ComNav makes a few units which
look like they'd work, but I'd like to hear that from someone other than
the manufacturer or salesman, preferably someone who owns one. The boat
is equipped with a Garmin 540 combination fishfinder/GPS chartplotter
which issues NMEA sentences.
--

Larry
rapp at lmr dot com

Larry wrote in
:

Still, I'd like to add an autopilot IF (and only if) it can operate at
trolling speeds (about 1 knot or 1.5 mph). ComNav makes a few units
which look like they'd work, but I'd like to hear that from someone
other than the manufacturer or salesman, preferably someone who owns
one. The boat is equipped with a Garmin 540 combination
fishfinder/GPS
chartplotter which issues NMEA sentences.
--



If this is the only electronics in your system, I think your GPS, not
your autopilot, is your problem.

GPS only CALCULATES your direction of travel. The GPS signal only
allows its electronics to figure out your position every second. That
display that says your boat is pointed 085 degrees is only a guesstimate
of the GPS electronics because it looked at the last few seconds of
where you've been and where you are....a little 085 from where you were
a second ago.

At low speed, a GPS is damned near USELESS as a compass input for the
autopilot to follow and shouldn't be used. Too many sailboats try to
autopilot in poor wind conditions with the same wandering results
because the GPS' idea of direction of travel over ground is wandering,
too.

What you need for the autopilot is a COMPASS SENSOR. Some are also
called Fluxgate Sensors because they use a solid state magnetic field
sensor, not a real compass. This device will tell your autopilot which
direction the boat is pointed in EVEN AT ZERO MPH, always telling the
autopilot to follow a MAGNETIC COURSE from its information, not a
wandering GPS course from lack of information.

Under 3-4 knots, the GPS is useless as a directional compass sense
device because of its calculated guess. Use a real Compass Sensor.
Most good autopilots have at least a Fluxgate magnetic sensor as part of
their package. Unfortunately, most installations pay way too little
attention to the fluxgate's mounting position way too close to magnetic
objects mounted "out of sight" in lockers full of magnetic junk and
CURRENT CARRYING DC POWER WIRING, which always radiates a strong
magnetic field, which drags off the fluxgate or compass sensor's
calibration in some odd fashion.

The magnetic sensor, whether fluxgate or real compass, needs to be near
the CG of the boat's axii, all 3 of them. It needs to be away from all
power wiring carrying any kind of appreciable DC CURRENT and away from
ALL MAGNETIC OBJECTS, anything made of steel or brass. That's a pretty
tall order in a small boat, but very necessary to maintain compass
course accuracy at very low speeds.

On a rolling pitching boat, the solid state compass sensors are much
better than the mechanical ones, which get moving around from the motion
and give false readings. It's also best to get one that's "self
compensating", one that you simply turn in a circle a few times, slowly,
and it makes its own compensation chart which it stores to make more
accurate fixes.

http://www.maretron.com/products/ssc200.php
just as an example.....

On Sat, 26 Apr 2008 12:19:00 -0400, "Gregory Hall"
wrote:

Just what the world needs - another autopilot jetboat jerk who hasn't a clue
as to how to safely operate a boat blasting around the water becoming a big
nuisance and even larger menace to all concerned.

Take your autopilot, and overgrown Jetski for that matter, and shove it up
your ass!

C'mon Gregory, Why don't you tell him how you REALLY feel?
--
Calling an Illegal Alien an "Undocumented Worker" is like calling a
Crack Dealer an "Unlicensed Pharmacist"

On Sun, 27 Apr 2008 03:57:55 +0000, Larry wrote:

away from
ALL MAGNETIC OBJECTS, anything made of steel or brass.

Since when is brass magnetic?

Casady

Edgar wrote:

You need an autopilot where you can alter the amount of response to a given
course deviation.
At trolling speeds you need much more rudder angle to correct a deviation
than you would at higher speed.
However, if you are trolling rather than maintaining course to a destination
you ought to be able to accept a greater amount of yawing about the set
course anyway.

Frankly, I knew that - can you suggest one? Thanks.
--

Larry
rapp at lmr dot com

Gregory Hall wrote:
Just what the world needs - another autopilot jetboat jerk who hasn't a clue
as to how to safely operate a boat blasting around the water becoming a big
nuisance and even larger menace to all concerned.

Take your autopilot, and overgrown Jetski for that matter, and shove it up
your ass!

--
Gregory Hall

Gregory,

Why don't you come tell me that personally. I live at 1 Indian Trail,
Colebrook, New Hampshire and we can talk about this face to face.

Lets see if your courage extends that far.
--

Larry
rapp at lmr dot com

The autopilot I had used a fluxgate compass. The trolling problem was
the result of incorrect response. It would overcompensate at low speeds
because of the amount of time it took between issuing a command (it
turned the wheel which directed the jet) and the boat moving. There was
no rudder feedback nor could it have been added easily. While there
were multiple levels of sensitivity which could be set, none of them
worked at low speed with the result that the craft overcompensated. I
think the unit was a Raymarine Sportpilot.

Normally, one mounts the fluxgate compass as close to the bow as
possible, but (naturally) away from anything ferrous like an anchor.
The only purpose of a GPS might be to plot a long course, but, as I
said, the main reason for adding an autopilot would be for trolling
single-handed.

I've been boating for over 50 years, and have sailed all around the
Carribean, so I'm not a novice. I've owned boats from 14 to 38 ft.
and am an EE so don't be afraid to get technical.
--

Larry
rapp at lmr dot com

"Larry" wrote in message
...
Gregory Hall wrote:
Just what the world needs - another autopilot jetboat jerk who hasn't a
clue as to how to safely operate a boat blasting around the water
becoming a big nuisance and even larger menace to all concerned.

Take your autopilot, and overgrown Jetski for that matter, and shove it
up your ass!

--
Gregory Hall

Gregory,

Why don't you come tell me that personally. I live at 1 Indian Trail,
Colebrook, New Hampshire and we can talk about this face to face.

Lets see if your courage extends that far.
--

Larry
rapp at lmr dot com


You're joking. He and his companions are cowards and liar. Maybe you're just
being mean, since I'm sure that it's obvious who and what they are. Shame on
you Larry!


--
"j" ganz @@
www.sailnow.com