Robust autopilot needed

[rgleason]

Thanks Nolex, Plumbean and Fi2010.
Nell's configuration is quite obviously going to determine some of this equipment choice.

[catsketcher]

A quick sketch of my setup (top views)

The notched belt is loose when helming. The motor arm is rotated to pull the belt tight when the autopilot is wanted. It would be nice to have the arm swing forward with a spring or shock cord and pull back with a remote pulley system.

[FlyingScot]

Originally Posted by noelex 77

As you point out, there seems little difference between the NAC-2 and NAC-3 other than the power output. However, the difference in power output between the two units is substantial:

The NAC-2 will provide a 8 A continuous output and a 12 A peak. The NAC-3 will provide a 30 A continuous output and a 50 A peak.

The choice between these two units depends on the power requirements of the drive unit. Specifying the NAC-2 for a drive unit that can consume above 12A will not work well.

Still not right. I listed the specs in post #26.
NAC-2 has 16A peak.

https://www.bandg.com/bg/type/autopi...ilot-computer/

[noelex 77]

Originally Posted by FlyingScot

Still not right. I listed the specs in post #26.
NAC-2 has 16A peak.

I think you may be right, but some websites list a 12 A peak (see photo below). Perhaps B&G have increased the output at some stage.

Anyway, all sources seem to agree the maximum continuous output, which is the more important figure is 8 A.

[rgleason]

Key differences in the control algorithms of the Raymarine EV-100 and the B&G NAC-2 autopilots:

• Raymarine EV-100:
  • Proportional Control: The EV-100 uses a proportional control algorithm. It adjusts the rudder angle based on the difference between the desired course and the actual heading.
  • PID Tuning: The system employs a PID (Proportional-Integral-Derivative) controller to fine-tune the response. It balances responsiveness and stability.
  • Adaptive Gain: The EV-100 adapts its gain settings based on sea conditions, optimizing performance.
  • Wind Vane Mode: It can maintain a specific wind angle relative to the boat.
  • Ease of Use: Generally straightforward for cruisers and coastal sailors.
• B&G NAC-2:
  • Sail-Specific Algorithms: The NAC-2 is designed with sailboats in mind. It incorporates specialized algorithms for sail trim and balance.
  • Advanced PID Control: B&G’s control algorithm fine-tunes rudder movements using PID control, considering both integral and derivative terms.
  • Heel Compensation: It compensates for heel angle, crucial for sailboats.
  • Integration with Instruments: Seamlessly integrates with B&G displays and instruments.
  • Offshore Performance: Suitable for offshore and bluewater sailing.

Remember that the choice depends on your sailing style, vessel type, and preferences. Both systems offer reliable performance, but the NAC-2 caters specifically to sailors.

[rgleason]

Will the Nac-2 use significantly more power than the nac-3 when steering the same boat in the same conditions?
Copilot answer:
The B&G NAC-2 autopilot computer is recommended for boats up to 10 meters (35 feet) in length. It delivers a standard power output of up to 8 amps continuous and 16 amps peak, along with a clutch output. This output is suitable for operating low-current drive pumps (such as the SD10) and hydraulic linear drives (like the HLD350) 1. On the other hand, the NAC-3 is rated at 30 amps continuous, making it more suitable for larger yachts 2. So, yes, the NAC-2 will use significantly less power than the NAC-3 under the same conditions.
=====


Really? Somehow I don't think so.

The more powerful Nac-3 will have power available if needed and when needed, but 98% of the time the power power requirements and use will be identical.


Do you agree?