Autopilot Wheel pilot

[ScooterC]

Hi all,
I have a Navico 4000 autopilot which has a belt running from the autopilot motor to a metal wheel on the steering wheel. The belt slips while under sail but works -kinda- under power. The notches are different on the wheel than on the drive motor so it seems to be a mismatched set??? but I can't find any used wheels anywhere. Is there a way to increase the tension or decrease the belt slippage on the wheel?

Thank for any input!

[chris95040]

Me, I'd get wheels and belts that were supposed to work with each other.

But maybe a belt tensioner, such as the one CPT sells here (Order Parts - CPT Autopilot Inc.) would work for you. I had a similar gizmo on a dirt bike. It squeezes the opposite runs of the belt together.

Looks like it also has an attachment to prevent it from wandering, although if your drive wheel is large enough diameter I imagine this wouldn't be necessary.

[mogulskibum]

There should be a lever on the motor head that can be engaged and disengaged to tighten the belt when using the autopilot and loosen it when you're not using it.

If you're engaging that lever and the belt is still slipping, then one of two things is the problem:
1. Incorrect installation, the motor head needs to be moved further from the wheel (note: if this installation has worked in the past, this probably isn't the problem).
2. The belt has stretched and you need a new one. The belts can still be found online, but it can sometimes be a challenge. If I remember right, they made three different sizes, measure yours and start looking.

[mogulskibum]

Here's a diagram (from the manual for the wp5000, which uses the same style motor/drive) - the red arrow indicates the lever that you move to engage and disengage the motor/drive belt:



I'm about 95% sure that the WP4000 and WP5000 use the same belts. If you measure from the center of the wheel to the center of the pivot point for the motor head (dimension 'A' in the below picture), you can figure out what belt you're looking for.

'A' = Navico part number
496 mm = WP B 506
593 mm = WP B 580 (this was the standard length)
712 mm = WP B 672

[ScooterC]

Thanks folks! Yup I understand the cam lever, I think I need a new belt and will gee it a try.

Cheers

[Snore]

You stated the auto pilot works well under power but not as well under sail. This sounds like the sail plan may not be balanced. A wheel pilot cannot develop the same torque as a human. If a person would have to work to keep the boat going straight, a wheel pilot will slip.

[GordMay]

Greetings and welcome aboard the CF, Scooter.

[ScooterC]

Thanks all for your excellent suggestions! So I was confused during the long snowy winter. My autopilot works well under sail not motoring. I think there is too much "prop walk" on the system and not enough belt tension so the belt slips. I'm not sure if the belt has stretched or what but if I hand tension it, it works. Off to find a belt tensioner. I can't seem to find any used wheels.