MiddayGun

B&G NAC-2 - No rudder feedback sensor

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Anyone using a B&G NAC-2 Autopilot without a rudder feedback sensor? 
Looking at the manual it seems it supports virtual rudder feedback, just wondering if anyone has any idea of how much if at all the autopilot performance will be compromised?

Currently have a Pelagic which works well most of the time, but would like to be able to steer off true wind angle, electronics setup on the boat is a fairly basic Triton displays / Vulcan MFD  setup. 

Boat is just shy of 28 foot, transom hung rudder, I can't see any way to add a rudder feedback unit to it. 

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How is your rudder actuated ? 
the extension os the linear actuator should be able to drive a “bell crank” to get rotation scaled to the sensor. 

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8 hours ago, LionessRacing said:

How is your rudder actuated ? 
the extension os the linear actuator should be able to drive a “bell crank” to get rotation scaled to the sensor. 

Transom hung with a tiller. 

1483805741_IMG_20180918_123209(Large).thumb.jpg.08948a7be2a5b9c62a632daee48ed9b3.jpg


Pretty simple arrangement, but not many options for fitting a sensor. 
I've seen some of the linear style feedback units that work in the same way as the tiller pilot arm, we used to use them as feedback units for the jet drives on the CTVs but they proved not all that reliable. Plus they're no good for mounting externally anyway.

ZSIM20188074.jpg.1c21131bc73bcbea229dee608e6a6900.jpg

 

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9 hours ago, LionessRacing said:

Thanks LionessRacing, I had look at that one, and the Octopus drive, they look handy bits of kits, especially for compact installs but I've not really been able to think of an elegant solution to pass the cable through to the outside of the boat without it looking a bit naff. Also, I know it says weather proof on the specs, but I've not sure how long the cable and fittings would last up when actually exposed to the elements. 

 
Solutions I've seen on other transom rudder boats have usually involved cutouts in the transom to mount a smaller autopilot tiller on the cockpit sole, not what I had in mind. 
The minis have transom rudders but due to the design they can fit a linear actuator on the cockpit sole. 

In theory I should be able to use my Pelagic linear drive with the B&G system using the 'virtual' rudder feedback option, I was just wondering if anyone was using it in this configuration & had any feedback they could give as to how well it actually works. 

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You could rig a string pot, and route a  line below through what ever you want, calibrating would depend on your Autopilot. 

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5 minutes ago, LionessRacing said:

You could rig a string pot, and route a  line below through what ever you want, calibrating would depend on your Autopilot. 

That could work. 
Looking at the manual for the NAC-2 it can take an analogue sensor and the manuals for their sensors indicate they use a pretty standard 0-5v output, so I reckon it should be possible to rig something up. 

Maybe something along these lines:

https://www.te.com/usa-en/product-CAT-CAPS0072.html?q=&d=484864 484868 484872&type=products&samples=N

IP67, plenty of travel for the application and good accuracy, also pretty compact.

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I had exactly this application.  NAC-2, Pelagic, 28' boat, transom hung rudder.  I ended up mounting the rudder sensor to the cockpit floor.  Looked stupid.  Worked great.

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On 10/19/2019 at 7:40 PM, Roleur said:

I had exactly this application.  NAC-2, Pelagic, 28' boat, transom hung rudder.  I ended up mounting the rudder sensor to the cockpit floor.  Looked stupid.  Worked great.

I am looking to do the same exact thing. Quick question, do you have to connect/disconnect the pelagic drive everytime that you want to engage the autopilot, or can you leave it connected all of the time?

I'm on the fence of going with the NAC-2 or simply with the Pelagic course computer package... 

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24 minutes ago, Floating Duck said:

I am looking to do the same exact thing. Quick question, do you have to connect/disconnect the pelagic drive everytime that you want to engage the autopilot, or can you leave it connected all of the time?

I'm on the fence of going with the NAC-2 or simply with the Pelagic course computer package... 

You have to disconnect it manually as well hitting standby. Although if I'm in a rush I'll just lift the tiller pilot off & let it go crazy while I steer the boat. 

As much as I'd like something clutch driven, its just feasible with my rudder arrangement, at least not without a large amount of work for something that will still look a bit naff. 
Eventually I'm looking to drive the Pelagic Actuator from a B&G computer, that way I can have a fairly integrated system that can still sail to TWA. 

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1 hour ago, Floating Duck said:

I am looking to do the same exact thing. Quick question, do you have to connect/disconnect the pelagic drive everytime that you want to engage the autopilot, or can you leave it connected all of the time?

I'm on the fence of going with the NAC-2 or simply with the Pelagic course computer package... 

I did both.  I put a switch in that took input from the NAC-2 on one side and Pelagic brain on the other.  That gave me some redundancy.  Then I had 2 Pelagic drives, two sockets in the deck, and two pins on the tiller.  My hope was to have redundancy on every aspect of the autopilot system.  Also had an emergency cassette rudder that could fit on the existing rudder gudgeons and the existing rudder could fit on the emergency gudgeons.  

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1 hour ago, MiddayGun said:

Eventually I'm looking to drive the Pelagic Actuator from a B&G computer, that way I can have a fairly integrated system that can still sail to TWA

That is my main concern. It would be nice to have ALL of the options that integrating with the b&g can do (TWA, AWA, Waypoints!), OR I save around $500 and only do the pelagic which can only steer by heading...

Seems $500 might be worth it. 

Is there a clutched drive that isn't over $1k? The pelagic drive at $275 looks hard to beat... 

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7 hours ago, Floating Duck said:

That is my main concern. It would be nice to have ALL of the options that integrating with the b&g can do (TWA, AWA, Waypoints!), OR I save around $500 and only do the pelagic which can only steer by heading...

Seems $500 might be worth it. 

Is there a clutched drive that isn't over $1k? The pelagic drive at $275 looks hard to beat... 

The problem you have is that no one makes a clutched tiller pilot drive. 
Existing units are all intended to be mounted under deck to a short tiller arm attached to the rudder stock beneath the decks, as we have transom hung rudders that solution doesn't work. 

The minis get away with it due to their twin rudder system, they have a centrally mounted quadrant that drives the two rudders, from photos I've seen they normally put the autopilot ram directly onto that, so above deck, but on the cockpit floor. 

I've not been able to find or think of any particularly elegant solution, so for the moment I'm sticking with the pelagic drive, out of all the tiller pilots its the most sturdy, if a little loud. 

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