I'm installing a ST5000 autopilot control unit with an Alpha Marine linear
actuator. The rudder position feed back from the Alpha is 10K variable
resistor (pot), 5K/5K is rudder centered..

I'm not sure what the Raymarine control unit is looking for.. The input on
the control head is 3 connectors, plus shield.

If someone has one of these rudder reference units sitting around, I would
be interested in knowing what the resistance from lead to lead is (excluding
the shield). Or what type of unit is this if not anolog.

I would appreciate any info..

Steve
s/v Good Intentions

Steve,

The blue lead is the common wire. The fixed resistance between the green and
red wires is 5.23K Ohms.

Resistance between the green and blue wires:
Wheel turned full to port - 3.34K Ohms
Wheel turned to center - 2.75K Ohms
Wheel turned full to starboard - 2.24K Ohms

Resistance between the red and blue wires:
Wheel turned full to port - 2.08K Ohms
Wheel turned to center - 2.67K Ohms
Wheel turned full to starboard - 3.20K Ohms

My steering system has +-36° of rudder motion with the feedback sensor set
up to Raytheon's suggested dimensions.

I have not calibrated the steering system or verified the center of the
sensor yet. According to these tests I'm off a little. The center seems to
be about 2.70K Ohms from green to blue and from red to blue. I get these
balanced readings with the wheel turn a little to starboard of center.

Rusty O

Our B&G Pilot's rudder position sensor is a linear plunger type. It
really makes no difference where "center" is during the installation,
because during the commissioning phase of the software setup you
center the rudder and get the boat going straight, then tell the
Pilot, "OK, this is rudder centered, right now. Make a note.", and
the Pilot notes the setting of where rudder center is, not any
specific value cast in stone. You do the same for the hard to port
and hard to starboard positions, shoving the rudder over to the stops
and telling the computer, "This is hard over to starboard. Make a
note.", with a setup on the display.

I'm sure the ST5000 has a similar software procedure to setup your
system. If it doesn't, return it and get a B&G. It's the most
amazing piece of gear bought for Lionheart. There's almost no noise
steering the boat. It's like a ghost is at the helm that knows
exactly how to steer and turn her, as if he's been turning her for 30
years......



On Sun, 29 Feb 2004 14:59:25 -0800, "Steve" wrote:

I'm installing a ST5000 autopilot control unit with an Alpha Marine linear
actuator. The rudder position feed back from the Alpha is 10K variable
resistor (pot), 5K/5K is rudder centered..

I'm not sure what the Raymarine control unit is looking for.. The input on
the control head is 3 connectors, plus shield.

If someone has one of these rudder reference units sitting around, I would
be interested in knowing what the resistance from lead to lead is (excluding
the shield). Or what type of unit is this if not anolog.

I would appreciate any info..

Steve
s/v Good Intentions




Larry W4CSC

No, no, Scotty! I said, "Beam me a wrench.", not a WENCH!
Kirk Out.....

Thanks Rusty, that is the information I needed.. It's not the same
resistance and the Alpha Marine but at least they are both using linear
resistance to determine rudder position.

My ST5000 can operate without the rudder reference but has provisions for
it. My main objective is to be able to tell the control when the drive has
(or is nearly) fully extended..

As Larry was discussing, the ST5000 has a calibration routine in the set up
procedures. Hopefully this routine will settle for these resistances
differences from OEM. If not, the drive unit is very service friendly and
the pot could be changed out without much hassle. Alpha Marine is still in
business and may have a suiteable replacement or recommended source.

I don't know if any of you have ever seen a Alpha Marine linear drive, but
it is a very heavy duty unit.. Mine was built for external tiller use, is
weatherized and has a 18" total travel with over 1000# of thrust. (I don't
think I would want to get between the tiller and the cockpit coaming with
this monster) and 4 sec. stop to stop. This thing is really well built and
is fully field serviceable.
http://i6.ebayimg.com/02/i/01/4f/42/81_1.JPG
http://i14.ebayimg.com/02/i/01/4f/06/f5_1.JPG

Since this drive draws more current than an Autohelm drive, I am building a
secondary drive controller.

Thanks again Rusty, for taking the time to document those resistance
readings.

Steve
s/v Good Intentions

On Sun, 29 Feb 2004 14:59:25 -0800, "Steve" wrote:

I'm installing a ST5000 autopilot control unit with an Alpha Marine linear
actuator. The rudder position feed back from the Alpha is 10K variable
resistor (pot), 5K/5K is rudder centered..

Steve
s/v Good Intentions


the rudder sensor on my RayMarine 5000 pilot is a 5K pot - I expect it
is just used as a vooltage divider, so your 10K pot should work fine.






--
Peter Bennett, VE7CEI
peterbb (at) interchange.ubc.ca
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