Hydraulic steering

[Csail]

I have got Vetus hyd. steering from two wheel positions. It has always been quite stiff so took it to the boatyard. They have redone the stern tube packing, changed oil & bled. It is still stiff!! With the ram disconnected the rudder is free and the steering light so what is causing it to be stiff under load?

 

[wingdiver]

Hi
Without knowing exactly how your kit is set up, these are some ideas:

1. Incorrect geometry at the rudder end. Effectively, you are pushing a rod that is like a little tiller. The nearer the pivot point the more difficult it is to move. However, moving the connection further away may then mean you do not have the range of movement so curing one problem may create another.

2. Incorrect pump sizes at either the steering wheel end or at the rudder end. If this is the case the pressure needed to move the ram pump will be higher than it should be. What number of turns lock to lock do you have? Ideally it should be 3 to 4. Mine is over eight which makes turning the wheel easy but a real pain in close quarters. If I increase the pump volume at the wheel I will reduce the number of turns but increase the effort to move the rudder (a bit like cog gears)

3. What about the oil in the hydraulic system itself. Have you ever changed the oil. This could be full of muck. It could even be too thick or too thin either of which could cause a problem.
D

 

[colinmi]

Sounds like the ram and the pumps might be mis matched. If this is the case, you either suffer as you are doing or the opposite and have steering that is too light and takes too many turns lock to lock. (How many turns lcok to lock do you have?)

I also have Vetus hyd steering with two positions, plus an electric pump for the auto pilot. Installed it myself during the winter and Im having a hell of a time getting the air bled out. If we dont get it sorted soon will need to rename the boat zig zag. Just cant seem to keep it on a course, then you over correct and so on and so on.

If you look on the Vetus web site there are tech manuals there which will tell you how to calc the correct pumps and ram sizes. Calc is based on rudder area and boat speed, if I rember correct. Or a quick mail to their tech people who are reasonably helpful.

Regards

Colin

 

[wotayottie]

Faced with the same problem on my Prout I increased the id size of the piping from pump to rams (used metal instead of the thicker walled plastic) and changed from SAE30 hydraulic oil (the standard and the one you are likely to have) to SAE10. Had a bit more of an issue with weapage past the ram seals, but the system became way lighter.

The test is does yopur steering feel heavier if you try to turn it faster? If that is the case tyhen the problem is likely to be with fluid flow. If not, then its an issue of geometry, joints etc. Or simply of gearing.