Hydraulic Steering Issue (Vetus)

[SV Kittiwake]

Our new to us boat has hydraulic steering, with a check valve and bypass valve, and a Raymarine autopilot.

When I turn the wheel all the way to port, the rudder arm that the hydraulic ram is connected too moves to starboard and the ram is contracted nearly all the way into the cylinder, i.e. its shortest extension.

The wheel then can't turn the ram back to starboard, the ram gets stuck when the wheel is hard over. Turning the wheel back to starboard, the wheel just spins and nothing happens to the ram... But if I engage the bypass valve (i.e. disengage the wheel steering) for a second then switch back, then the ram will re-engage and we can carry on steering as normal.

It's not a massive issue most of the time, but it's worrying manoeuvring in the marina and realising the rudder isn't responding, and having to take a couple of seconds to re-engage it.

Can anyone give any clues what this might be? From the wheel turning but the ram not moving, could it be that the fluid is bypassing something?

Thanks for any help!
Ryan

 

[knuterikt]

Could It be a missing end stop?

 

[PCUK]

What happens when you use the autopilot to move the rudder hard to port?

 

[SV Kittiwake]

Hmmm could be, is an end stop the same as a rudder stop? We don't have them as there's no easy way to put them on our rudder. I tried creating a similar solution by putting washers over the ram, so that it couldn't retract too far. But the same thing occurred with the ram locking.

 

[SV Kittiwake]

I hadn't tried moving it far over with the autopilot, it works fine in normal range (near centre) but I'll give it a go in the morning and report back.

 

[NormanS]

In an ideal world it's reckoned that 35° each way, is the maximum angle for a rudder, except in a few highly specialised situations. It is normally arranged so that the tiller arm, or at least part of the internal mechanism, comes up against a stop to prevent any movement beyond this angle. The internals of the hydraulic ram should not be the limit.
What angle can yours go to, and what determines the limit?

 

[SV Kittiwake]

So the autopilot will only move the rudder to 25 degrees whereas the wheel can move it to about 29, so the autopilot can't get the ram to lock. I moved it over with the wheel then put the autopilot on auto whereby it managed to overcome the locked ram problem and moved the rudder nearer centre.

I tried improvising a rudder stop with some dyneema cord (there's no easy way to make a solid rudder stop near the rudder arm). I couldn't get this to stop the rudder being pulled to the point where the ram is fully retracted, but the tension in the cord did pull the arm back enough that the locking problem didn't happen. I might try to make a rudder stop with a wire strop but it'll limit the max rudder angle to less than about 28 degrees.

If anyone has any other ideas I'd love to hear them!

 

[rogerthebodger]

What Vetus steering pump do you have.

I have Wagner which is a similar design.

If the steering pump is driving the cylinder to its extreme end I wander if the pressure relief valve in the steering pump is opening and jamming in the open position causing the steering to free wheel

 

[maxi77]

Sounds like a check valve problem. Once you release any internal pressure the system starts to work again makes it sound as if part of the system remains pressurised stopping the check valves working properly. Probably worth getting it looked at by a hydraulic expert