Hydraulic steering basics

Dutch01527

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My 28 foot Dehler is fitted with a wheel and hydraulic steering. I like it but know very little about hydraulics.

Could anyone help with answers to a couple of questions:

1) The rudder stays in the position it is set in even if I let go of the wheel. When the boat is under sail and balanced well I can set a tiny bit of helm and let go of the wheel for a long time - 30 minutes is the record to date. Is it normal? Some sort of non return valve that isolates the rudder pressure from the wheel?

2) What maintence is required? Fluid changes, lubrication?

Very basic questions I know but expert help would be appreciated.
 
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Sandy

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Hello Dutch01527

I also have a hydraulic steering.

Wheel setting for a well balanced boat sounds about right, personally I miss the feedback you get on non-hydraulic systems.

The maintenance really depends on the manufacturer's instructions. I have a issue where at the end of a hard day the "top" of the wheel can be as much as 25 degrees to port or starboard, never got to the the bottom of it, there must be a "leak" somewhere in the system. Currently I am not that fussed about it as "resetting the wheel" is not that difficult.

The one thing to be careful about is possibility of turning the hydraulic system off! A crazie 5 mins last summer as I reversed out of the berth and found I had no steerage. Thankfully, the emergency tiller was to hand.

What system do you have, Vetus here.
 

NormanS

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1. is normal, because the fluid cannot pass back through the pump. (Your wheel directly turns the pump, which directs the fluid to the ram).

2. In this type of use the hydraulic oil will last for years. There is probably a sight glass or possibly a dip stick on the pump, which you can use to make sure that the oil level is correct. If you find that it is going down, it has to be going somewhere, so look for leaks at connections, ram etc. The only other routine maintenance would be lubricating link pins on the ram and tiller arm, and rudder stock seal or packing.
 

Dutch01527

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Wheel setting for a well balanced boat sounds about right, personally I miss the feedback you get on non-hydraulic systems.

I understand that view but for me the convenience of being able to let the wheel go and sort things out is worth the compromise on feedback. Trying to tack single handed with the tiller stuck between my legs or having to tie off the tiller before nipping up to the foredeck is a pain. For me it would be racing and/or fully crewed = tiller. Cruising short handed = wheel.
 

penberth3

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...I have a issue where at the end of a hard day the "top" of the wheel can be as much as 25 degrees to port or starboard, never got to the the bottom of it, there must be a "leak" somewhere in the system. Currently I am not that fussed about it as "resetting the wheel" is not that difficult...

I guess that's a bit of internal leakage causing it to "slip". Not something I'd worry about.
 

PCUK

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I have a issue where at the end of a hard day the "top" of the wheel can be as much as 25 degrees to port or starboard, never got to the the bottom of it, there must be a "leak" somewhere in the system. Currently I am not that fussed about it as "resetting the wheel" is not that difficult.


Completely normal and not a fault. This is why you can't use a mark on the wheel to show midships.

The one thing to be careful about is possibility of turning the hydraulic system off! A crazie 5 mins last summer as I reversed out of the berth and found I had no steerage. Thankfully, the emergency tiller was to hand.


How did you manage to "turn off" the hydraulics? Never heard of such a thing!
 

NormanS

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I have a issue where at the end of a hard day the "top" of the wheel can be as much as 25 degrees to port or starboard, never got to the the bottom of it, there must be a "leak" somewhere in the system. Currently I am not that fussed about it as "resetting the wheel" is not that difficult.


Completely normal and not a fault. This is why you can't use a mark on the wheel to show midships.

The one thing to be careful about is possibility of turning the hydraulic system off! A crazie 5 mins last summer as I reversed out of the berth and found I had no steerage. Thankfully, the emergency tiller was to hand.


How did you manage to "turn off" the hydraulics? Never heard of such a thing!

Some hydraulic steering systems are fitted with a normally closed bypass valve. When commissioning or refilling, opening this valve means that you can keep turning the wheel, thereby getting rid of any air in the pipework. If the valve was inadvertently opened, the steering would indeed not work.
Many are also fitted with a pressure relief valve, so that if great and excessive force was put on the rudder blade (think collision with a whale :D) the valve opens, and protects the pipework. A bit like a fuse in an electrical circuit. A faulty or passing prv could also cause loss of steering. These two functions are sometimes provided in a single prv/relief valve.
 
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superheat6k

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Oil in hydraulic systems is not subject to anything which will degrade it, so unlike engine oil requiring say an annual change, the hydraulic oil, as long as not contaminated, will last almost indefinitely. Yes you can change it, but you are as likely to introduce contaminants during the process as remove any.

The pumps will let a very small amount past the piston seals, as will the delivery cylinder, so perhaps more or one tack or the other will create a small variation, and yes no feedback with hydraulics, so this likely explains the offset observed. If you had a electric pump autohelm assisting then the wheel can end up literally anywhere. Annoying for those with OCD, and this who like a Turk's head at the top of the wheel. But then you can always tie a fresh one each evening !
 

Sandy

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I have a issue where at the end of a hard day the "top" of the wheel can be as much as 25 degrees to port or starboard, never got to the the bottom of it, there must be a "leak" somewhere in the system. Currently I am not that fussed about it as "resetting the wheel" is not that difficult.


Completely normal and not a fault. This is why you can't use a mark on the wheel to show midships.

The one thing to be careful about is possibility of turning the hydraulic system off! A crazie 5 mins last summer as I reversed out of the berth and found I had no steerage. Thankfully, the emergency tiller was to hand.


How did you manage to "turn off" the hydraulics? Never heard of such a thing!
There is a valve in the system that overrides the wheel allowing you to use the emergency tiller. We had been moving a lot of stuff in and out of the cockpit locked and it accidentally got moved.
 

NormanS

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There is a valve in the system that overrides the wheel allowing you to use the emergency tiller. We had been moving a lot of stuff in and out of the cockpit locked and it accidentally got moved.

Yes, that's the bypass valve as mentioned above. It allows the ram to go back and forward without pressurising the system.
 

NorthUp

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Feedback, or 'feel' is possible with a hydraulic system- just do not use pilot operated check valves in the system. They are the valves that prevent the wheel from being turned by the rudder forces. This however is not an option if you have more than one wheel, or a hydraulic
Pump powered by engine / electrics for an autopilot- the autopilot would turn the wheel instead of the rudder.
 
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