Question on autopilot

[Daniel]

In my 1978 Swan 411 there is an old NECO autopilot. I recently fixed
some minor faulty circuitry and it now works as it is supposed to do.
Too bad that it is a vintage device and, for example, does not have a
NMEA input, the course is set on an absolute 360 deg dial and there is
no whatsoever display that gives information on the set/actual course.
I would like to upgrade it but the 12Volt/20A servomotor under the
steering wheel works well and I would like to keep it: it is presently
controlled by two relais'. Also the clutch works and there is a rudder
feedback, probably a variable resistor, in the same assembly. Keeping
them would reduce the cost by a relevant amount and, in particular,
would almost zero the mechanical adapting of the steering system. On the
market there are many display/control units available with all the
modern facilities; using one of them should not be impossible.
The main problems I foresee are: i) compatibility between the output of
the new unit and the relais/servomotor, and ii) possible installation of
a new rudder feedback unit.
Has anybody in the NG faced those problems and solved them?
Daniel

 

[Steve]

I'm in about the same situation, having a pre-ST autohelm 3000 that is under
powered and doesn't take NMEA input. Otherwise it works fine in calm water
with the course set manually..

I have already found a solution to the increase in power, however I'm still
searching for an upgrade to the control head.

Be advised that none of the pre ST autohelm/Raymarine pilot will except
NMEA input.. Even the Z80 interface seems to dislike the current 0183
formats.

Then we get into the ST models. Even some of these early ST models still
required an interface to convert the NMEA to SeaTalk before it goes to the
AP..

I investigated a ST5000 on ebay that had a location for the NMEA connection
and the markings were molded into the case, but the connector pins holes
were empty.. Must have been a very early release..

Then there is the problem of your drive motor clutch.. I believe that the
ST5000 is the first model to have a clutch control in the control head..
Here again, I would approach this with caution since there are going to be
control heads sold for tiller pilots that don't require a clutch release.

I would recommend staying away from the current generation since the control
head don't necassarily have the course computer in them, just some secondary
circuits, display and buttons. The course computer is incorporated in some
other nav station equipment..

I think your approach is correct as you have evaluated each of the system
components and determined what to keep and what to abandon.. Your boat size,
like mine make it nearly impossible to purchase an off the shelf AP system..
My boat being 13.5 ton and tiller steered.. Even the largest tiller pilot
system comes up short.

Good luck.

 

[Philip]

Steve,
I'm in the same situation as you, in that I have just sold my pre-NMEA
AH3000 control head, with the intention of buying an ST3000 control head.

I've had two good prices on buying just the control head as I am keeping the
drive motor. Most companies want you to buy the complete system.

Raymarine (UK) have confirmed that the ST will directly replace the AH but
with the added facility of Seatalk. I have the interface from my previous
boat, so will be able to marry both parts of the system into my GPS.

I was intending to upgrade to an ST4000, but believe that I would have to
install rudder feedback, as well as buying a fluxgate compass unit to feed
the 4000. With just replacing the AH3000 with the ST3000, that will be all
there is to it.

regards,
Philip, s/v Oyster

 

[Rodney Myrvaagnes]

I would recommend staying away from the current generation since the control
head don't necassarily have the course computer in them, just some secondary
circuits, display and buttons. The course computer is incorporated in some
other nav station equipment..

The current ST4000 has the course computer in the head. It comes with
a fluxgate compass in a separate housing and the display gives you a
compass even if you aren't using the pilot.

It is also a Seatalk display if you have a sender for other info.



Rodney Myrvaagnes NYC J36 Gjo/a


"Curse thee, thou quadrant. No longer will I guide my earthly way by thee." Capt. Ahab

 

[Sheldon Haynie]

Look at the B&G control heads, they are readily interfaced to the servo
drive type such as the Lewmar rotary.
With the NMEA and other sailing instruments interfaced, you can sail to
POLAR, sail to compass, sail to waypoint, sail to wind or have the pilot
execute a tack or gybe.

The current ST4000 has the course computer in the head. It comes with
a fluxgate compass in a separate housing and the display gives you a
compass even if you aren't using the pilot.

It is also a Seatalk display if you have a sender for other info.



Rodney Myrvaagnes NYC
J36 Gjo/a


"Curse thee, thou quadrant. No longer will I guide my earthly way by thee."
Capt. Ahab

--
Sheldon Haynie
Texas Instruments
50 Phillipe Cote
Manchester, NH 03101
603 222 8652

 

[Ger]

Daniele,
I may have a solution for you, provided you know a bit about electronics and
can handle a soldering iron.
The autopilot in my Nicholson 39 was also the old NECO with the drive under
the wheel.
I have replaced the autopilot by a Robertson AP200, but I left the old NECO
drive in place, because replacing it by a new drive suited for a modern
autopilot would require a lot of mechanical engineering work plus additional
costs for a new drive.
I am sure you recognise this.
The problem is that the NECO drive is driven by heavy relais and exotic
windings in both the motor and clutch, requiring special drive electrics.
There is no possibility to have the drive controlled directly by a modern
autopilot.
The solution is to completely remove all electronics (relais,
rudder-feedback potmeter etc) from the drive and replace it by a new
electronic circuit, acting as interface between your new autopilot and the
drive motor and clutch.
I have done this and it works now like a dream.
I got the electronic schematics and print layout from somebody here in
Holland, and with some minor modifications I got it up and running.
The circuit board with electronics fits nicely in the space where the relais
were sitting.
However, the person from which I received the schematics (the designer) is
the owner of the design and I need his approval of course to pass it to
others.
I can ask him for his permission if you are interested in this. Just let me
know if you are.
If there are other readers of this message also interested in this specific
NECO subject they are of course also welcome to react.
If you want to reply directly please locate the email address on my website
via the menubar at the top.
Regards,
/Ger Rietman
www.sailsoft.nl

PS: Daniele, is it possible that I sent you the Neco user manual a few years
ago?

 

[Ger]

For people interested: I have placed a picture of the solution here:

http://test.sailsoft.nl/neco/AP-Neco-drive.jpg

Rgds,
/Ger Rietman
www.sailsoft.nl

 

[Derek Rowell]

The ST4000 does not require rudder feedback.

Steve,
I'm in the same situation as you, in that I have just sold my pre-NMEA
AH3000 control head, with the intention of buying an ST3000 control head.

I've had two good prices on buying just the control head as I am keeping the
drive motor. Most companies want you to buy the complete system.

Raymarine (UK) have confirmed that the ST will directly replace the AH but
with the added facility of Seatalk. I have the interface from my previous
boat, so will be able to marry both parts of the system into my GPS.

I was intending to upgrade to an ST4000, but believe that I would have to
install rudder feedback, as well as buying a fluxgate compass unit to feed
the 4000. With just replacing the AH3000 with the ST3000, that will be all
there is to it.

regards,
Philip, s/v Oyster