rudder moving when wheel doesn't

[recurveman]

I'm not sure what title to give this thread but I need to find a solution.

Here are the issues. I have a lecomble and schmitt system.

When in auto pilot the boat will go off course to the starboard direction about 40-70 degrees before it gets back on course.

When holding the wheel in place the rudder will move to one side of the other while docking. When more power is applied the rudder moves faster to one side. It goes different directions depending on if you are going forward or reverse.

while hand steering the boat it will constantly head to starboard and the wheel is merely a suggestion. I could turn the wheel a full turn over maybe a minute and the boat will still be going strait. If I didn't turn the wheel the boat would be going hard starboard.

Does anybody have an idea of what the problem is and how to fix it?

[Sailmonkey]

Have you bless all of the air out of the hydraulic system?

[recurveman]

Originally Posted by Sailmonkey

Have you bless all of the air out of the hydraulic system?

Yes. We recently flushed the system and bled the system.

[paralog]

Originally Posted by recurveman

I'm not sure what title to give this thread but I need to find a solution.

Here are the issues. I have a lecomble and schmitt system.

When in auto pilot the boat will go off course to the starboard direction about 40-70 degrees before it gets back on course.

When holding the wheel in place the rudder will move to one side of the other while docking. When more power is applied the rudder moves faster to one side. It goes different directions depending on if you are going forward or reverse.

while hand steering the boat it will constantly head to starboard and the wheel is merely a suggestion. I could turn the wheel a full turn over maybe a minute and the boat will still be going strait. If I didn't turn the wheel the boat would be going hard starboard.

Does anybody have an idea of what the problem is and how to fix it?

Could it be a loose Quadrand on the rudder shaft, maybe the key on the shaft has come loose broken.?

[carlosproa]

And your rudder has no bent on it? I mean the rudder stock..

[chris95040]

Originally Posted by recurveman

I'm not sure what title to give this thread

Think you nailed it

[recurveman]

Originally Posted by paralog

Could it be a loose Quadrand on the rudder shaft, maybe the key on the shaft has come loose broken.?

We can see the rudder arm moving and it corresponds with the electronics of where it says the rudder should be and the boat moves the direction it should. The issue is the steering wheel never moves and the rudder will move. It's like the hydraulic system is leaking by or something. We can also move the wheel and the arm attached to the shaft will move sometimes. It's like the wheel and rudder aren't connected all the time.

[PippaB]

Most multi-station hydraulic steering systems (and an AP + single wheel count as two stations) feature a “non-return valve”. If, when it was working properly the wheel did not turn when the AP was steering then you have a non-return valve. The non-return valve is what allows one station to steer without having the other stations also turning. (If your wheel has always turned when the AP is steering then the rest of this post is moot).

I would guess that there is some debris or blockage in the non-return valve or a poppet that no longer seats properly/has a bad seal, or something along those lines. In that condition the AP and wheel would no longer be isolated and some odd things could happen. That, at least, is where I would start looking.

I don’t know the L&S system in particular, some non-return valves are built into the helm pumps, with others they are an external valve block. Do you have part numbers for your helm pump and AP system?

[recurveman]

Originally Posted by PippaB

Most multi-station hydraulic steering systems (and an AP + single wheel count as two stations) feature a “non-return valve”. If, when it was working properly the wheel did not turn when the AP was steering then you have a non-return valve. The non-return valve is what allows one station to steer without having the other stations also turning. (If your wheel has always turned when the AP is steering then the rest of this post is moot).

I would guess that there is some debris or blockage in the non-return valve or a poppet that no longer seats properly/has a bad seal, or something along those lines. In that condition the AP and wheel would no longer be isolated and some odd things could happen. That, at least, is where I would start looking.

I don’t know the L&S system in particular, some non-return valves are built into the helm pumps, with others they are an external valve block. Do you have part numbers for your helm pump and AP system?

OK I think I follow most of what you said. A bit over my head but I'm learning fast. My helm pump model is 2200413D. I'm going to enclose a pic of the helm pump too. I believe this is what you want me to take apart and inspect. Correct? I'm guessing my issue will be in the square block that has the two hoses coming into it. Correct?

FYI - my wheel doesn't turn when AP is on. never has.

Thanks,

[skipperpete]

Is there a manually operated bypass valve to allow the use of an emergency tiller or to align the rudders ? If that was left slightly open it would cause the symptoms you describe...... also a leaking piston seal in the cylinder could cause the same symptoms as the oil would leak into the return side and not push the piston when pressure was applied.
Pete.

[recurveman]

Originally Posted by skipperpete

Is there a manually operated bypass valve to allow the use of an emergency tiller or to align the rudders ? If that was left slightly open it would cause the symptoms you describe...... also a leaking piston seal in the cylinder could cause the same symptoms as the oil would leak into the return side and not push the piston when pressure was applied.
Pete.

The system does have a bypass valve. We made sure it was shut. I guess it could be leaking by but not sure how to test that. It is a simple 1/4 turn ball valve.

[boatman61]

Just a guess but could your rudder have come loose from the stock.. as I said, just a guess not knowing its construction.
Maybe dive on it and give it some jerks while someone on board eyeballs the moving gear in the stern.

[boatman61]

Opps.!!!!!
Just looked at your info by the avatar and see its a Cat..
With your statement 'rudder moving' I assumed the singular referred to a mono.

[boatman61]

So.. Have you found the problem and a solution.???

[recurveman]

Not yet. I have a hydrolic guy coming by in a few minutes to take a look at it. I think it will be one of the valves in the AP or helm pump.