Can I use a proportional/delay hydraulic valve with my autopilot?

[niftyc]

Hello kind forum-mates,

I have bought a 2000 custom boat that I am still figuring out. We are noticing that the autopilot noise in the main berth is nearly intolerable when underway although the autopilot operates normally.

It is a Robertson AP20 connected to a custom hydraulic system. I had a friend who is a hydraulic expert out to look at the system and we IDed the noisemaker as a Hystar directional valve, connected to the Robertson by a wire.

Some effort has already been made to quiet this valve but it is not working. It has been isolated on a rubber mount and it has been located as far aft as as possible. It is now in the engine compartment, which has sound insulation. However it is a steel boat using metal hydraulic lines and the noise is transmitted by vibration very effectively up these lines and can be heard throughout the boat.

My friend says that in the hydraulic industry they refer to these as "bang bang" valves because the fast 0 to 100% response produces a bang on actuation. He said there are other kinds of valves that could be used. With a proportional or delay valve you would sacrifice a very small amount of response speed but the valve would be silent. These valves are not expensive -- a couple hundred he said.

This sounds too good to be true but I was thinking it would be great to check in to see if anyone else had tried this, as my friend works mainly in industrial automation and not boats, although he has done some boats. I did find a mention of this strategy in passing on one post: https://www.cruisersforum.com/forums...se-145339.html. But not much information is given.

I'm pretty sure that adding a delay is not going to affect the operation of the steering or autopilot because the boat's response is already quite delayed. I love the boat but it handles like a battleship. And he was saying that the added delay might be on the order of fractions of a second.

Does anyone have experience with moving their autopilot to a silent valve?

Hoping hoping hoping

[tkeithlu]

The manual for that unit:

https://echomastermarine.co.uk/asset...0%20Manual.pdf

allows for two reversible pumps, in addition to contimuous pumps with reversing valves. My Simrad works by a reversing pump, which has no valve noise involved, since the valves are passive and spring loaded. All you hear is the whine of the motor pushing the rudder one way or the other.

Central to this is not valve time but rudder angle time, in degrees per second. If you look at page 4 in the manual (1.2.7) you see the specification. Your choice of unit is dependent on the size of your steering cylinder.

Consider changing over or changing to a valve that still lets you meet the rudder angle requirement. I'd go with the motor - it sounds like a better system overall.