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Thread: A Hydraulic Steering Puzzle

  1. #1
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    Default A Hydraulic Steering Puzzle

    I now have my hydraulic steering system working without a leak anywhere - nothing leaking at all.

    The system has 4 pipes running from the pump which is driven by simply turning the helm. these run to an hydraulic cylinder positioned to control each rudder. It has an isolation valve on each of the two rudders. When you open this valve you can adjust the position of the rudder - in effect you centre the starboard rudder where the sensor is and then open the port isolation valve and adjust that to centre - close it and you have both rudders in sync. All the valve does is connect the two pipes feeding the cylinder together so that as you push to centre the rudder the fluid is moved from one side to the other of the cylinder.

    But with those valves closed and both rudders centred after 5 days there was no movement left on the port rudder- somehow it had moved totally out of sync with the starboard rudder.

    The system is well bled so its not air.

    The rudders do push on hydraulic cylinder with every wave - just a touch and this contact touch is what is doing the increasing out of sync situation.

    My theories to date are:-
    1. The isolation valve is slowly leaking so that fluid is moved from one side to the other.
    2. The Hydraulic pump is somehow moving fluid from one side to the other.

    These are just guesses.

    Has anyone ever experienced this problem and has anyone any ideas what this could be?

    We have no idea what it will be like underway and our reserve position before we set of on the next 3000 mile leg is that we simply open the valve on the port side so that the rudder is not controlled and just goes with the flow leaving the starboard rudder to do all the steering.

    Any help would be appreciated.
    Safe Sailing
    Paul
    Blog: www.suliere.com

  2. #2

    Default Re: A Hydraulic Steering Puzzle

    We've had this problem. For us it was the seals within the ram leaking, allowing fluid to bypass the piston. This caused the position of the pistons to go out of alignment. We had the seals in the rams replaced in El Salvador, of all places. A sparkling clean place in the middle of a squalid neighborhood whose business was to repair tractors, backhoes and the like had the seals in stock. Ours are from Lecomble & Schmitt.

  3. #3
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    Default Re: A Hydraulic Steering Puzzle

    Thank you for that.
    Ours is the same Lecomboe & Schmitt.
    However we have just fitted a brand new cylinder from them hence that the last thing we expected.
    We did order 3 spare sets of seals at their extortionate prices so we can replace - no idea how difficult that is but it must be fairly easy. In fact the original cylinder did not do this although it had a seeping hydraulic leak so I may set about putting one of the sets of seals in that and changing it back.
    I do not know how this fluid leak, however it is happening, will effect the rudder when underway. Given that the leak might go both ways as it were.
    Any other ideas?
    Safe Sailing
    Paul
    Blog: www.suliere.com

  4. #4

    Default Re: A Hydraulic Steering Puzzle

    You should have two cylinders, so it may be the other one. We did buy a set of seals from them but installed the standard ones from the shop. I suspect they are standard sizes. They were just O rings and seals. We had some control over the defective rudder, but it was still no fun to steer the boat in that condition. I imagine it was essentially steering under one rudder, but I am not certain what the defective one was doing. I would not want to go too far like that.

  5. #5
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    Default Re: A Hydraulic Steering Puzzle

    I know more than one St Francis lost a rudder in crossing the Atlantic from Case Town and did not know it until they hauled out at the other end.
    When it was being fitted the chap helping me did push the cylinder hard to adjust it when the calve was closed and it moved. I remember being worried as the valve was not open but shrugged it off as we opened the valve and adjusted no problem. So maybe it is the new cylinder...then maybe not Oh joy, Oh Joy.
    Safe Sailing
    Paul
    Blog: www.suliere.com

  6. #6
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    Smile Re: A Hydraulic Steering Puzzle

    Ok I have now taken the original cylinder apart - very easy but the O ring kit for that cylinder has 8 or rings and I can only see 5 BUY they fitted those lock made up one in Panama - so the question is did they miss some out? Or does the kit have 3 spares in it?

    next the hard ring on the piston - I have no idea how to get it on.

    has anyone ever fitted one of these?

    Tomorrow Immigration come to check then state of my boat an
    and make sure I have issues - so far they have been excellent.

    In the meantime we continue to live in this Dr Doolittle world where the seals sleeping on the floor do not even bite when shoved into with shoes, the pelicans sit alongside you whilst the herons strut around with an aloof look at all the goings on. There are many worse places to be stuck but we do so want to leave.

    Tonight the sat system is on a plane from the mainland to us and we are visiting the agent here on Good Friday to see where on the island it is - the hope is to have it by Saturday.

    In this prolonged saga Customs before they cleared our Fedex insisted on a logo on the invoice and rejected our online receipt! Then having supplied invoices with logos on them Fedex charged us an extra $125 for handing the invoices over to Customs - it called appointing a clearing agent
    Safe Sailing
    Paul
    Blog: www.suliere.com

  7. #7

    Default Re: A Hydraulic Steering Puzzle

    Quote Originally Posted by ForumAdmin View Post
    next the hard ring on the piston - I have no idea how to get it on.

    has anyone ever fitted one of these?
    The wear ring in the centre of the piston has a split in it and can be prised off carefully. It retains a solid pin that holds the piston onto the rod. There is an o ring inside the piston that seals it against the rod. If the piston has been slid on from the wrong end, o ring first, it will likely be damaged as it passes over the sharp edges of the hole for the pin.

    I have custom duplex rods with chamfered holes and my pistons modified to accommodate 2 o rings. Most manufacturers supply cheaper chromed rods that deteriorate very quickly in the marine atmosphere. I also use urethane energised seals. They still require the occasional realignment anything from weekly to monthly. I have 2 rudder indicators and one of my bypass valves can be remotely operated from the helm.

    There are numerous other possible reasons for your problems and creep will always be present despite what the manufacturers and salesmen will have you believe.

    If you have fixed rudders (mine are kick up) then fit a tie bar, failing that a push pull cable between the rudders.

  8. #8
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    Default Re: A Hydraulic Steering Puzzle

    All that was very helpful... thank you.

    I will look at fitting tie bar .
    Can you explain the push/pull cable a bit more please?

    I can see no split in the ring that goes onto the piston so i am still confused about that.

    Your point about they always need adjusting anyway is interesting. In this case it so severe that after on week at anchor there is no movement left in one direction You an only go in circles!
    Safe Sailing
    Paul
    Blog: www.suliere.com

  9. #9
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    Default Re: A Hydraulic Steering Puzzle

    one of my bypass valves can be remotely operated from the helm.
    So you just line up the indictor to central zero position and then open the bypass valve to force the rudder into sync?
    Can you please explain why you have the remote control and how you use it?
    Safe Sailing
    Paul
    Blog: www.suliere.com

  10. #10

    Default Re: A Hydraulic Steering Puzzle

    Quote Originally Posted by ForumAdmin View Post
    All that was very helpful... thank you.

    I will look at fitting tie bar .
    Can you explain the push/pull cable a bit more please?

    I can see no split in the ring that goes onto the piston so i am still confused about that.

    Your point about they always need adjusting anyway is interesting. In this case it so severe that after on week at anchor there is no movement left in one direction You an only go in circles!
    Not sure about your wear rings. You should be able to open them out so they push over the centre of the piston. A picture ?

    A push pull cable is the same as an engine throttle / gear change cable (Teleflex type). Fitted on the tiller arms it will prevent too much differential movement between the rudders, when there is no pressure. Pro Kennex among others used this method.

    The problem with U-cup seals that are fitted in all rams is that they are typically spec'd for 0-300 bar, the higher the pressure the better the seal. When you are at anchor or even sailing on a cat (no lee or weather helm) there is zero pressure exerted on the seal, the minutest imperfection in the rod or seal or in-balance between the rams will allow fluid to get past. Gentle rocking movement at anchor is often the worse. This is not a problem on a mono as with only one rudder it is not noticeable anyway. This is why a mark on the wheel can never be used as a rudder indicator on a hydraulic steering system even on a mono.

    Using energised seals, these are energised by a spring or in this application an o-ring within the U-cup, maintains a physical force on the lip even when there is no pressure.

    Procedure for realignment. My port bypass valve is operable from the helm. Turn AP off. Establish a course straight ahead using the port rudder indicator. Open the valve and adjust the stb. rudder using the wheel until it shows zero on the stb. indicator. Close the valve. Check both are aligned. If the sea state is bad it needs to be done very quickly, not difficult, or a couple of times to get perfect alignment.

    All of this assumes that you have properly bled the system as even a small amount of air, especially within the hydraulic tie between the rams, will give all sorts of problems.
    Last edited by Peter; 14th April 2017 at 08:13 PM.

  11. #11
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    Default Re: A Hydraulic Steering Puzzle

    That is very informative. Thank you again.

    My piston ring has a hard beveled outer seal but it seems a soft under seal within it. There is no split in the hard ring. The pin is well away from the ring. I have not knocked the pin out as yet and think its best to a workshop where they do these things – if I can find one. It maybe that the front face of the piston comes away as the hard seal does not even come totally flush with the face of the piston – you can fit a piece of paper in the gap. Remember this is the cylinder that did not have this problem. The problem has only occurred since fitting the new cylinder.

    The wifi here is the worst we have ever experienced. Everywhere you eat has free wifi but most of the time I cannot even establish a connection hence an image may not be possible but I shall try.

    Currently it takes about 15 hours of gentle rocking at anchor to lose all the travel to port. That if the rudders are left in the central position but if centered and left over to port the rudders do not move out of sync.

    As I know that St Francis 50’s once had a problem with losing rudders and one even crossed the Atlantic before realising it had lost one, I hope that the next leg of 3000 miles maybe ok on one rudder or with two and me doing the occasional adjustment with the bypass valve. Galapagos is one of the worst places to get this fixed but I will investigate a push/pull cable.

    I have now arranged for a specialist hydraulic chap to come and see the issue on Sunday – then we go back to his workshop so I can see the new seal set fitted to the old cylinder. That replaced the new cylinder if that does not work we are in the same situation but if it does work I will have the piston seals replaced in the new cylinder. I bought three sets of seals along with it.

    Thst is the plan. I am amazed they work on Easter Sunday!
    Safe Sailing
    Paul
    Blog: www.suliere.com

  12. #12
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    Default Re: A Hydraulic Steering Puzzle


    This is the piston.
    The ring has no split in it and does not cover the pin.
    Attached Images Attached Images
    Safe Sailing
    Paul
    Blog: www.suliere.com

  13. #13

    Default Re: A Hydraulic Steering Puzzle

    Hi Paul, it looks as though these are single acting rams and the black ring is the seal itself. There appears to be no wear ring to retain the pin. The open end of the U faces away from the pin. Round off the end of a thin bladed flat screw driver and prise it out. It will come out. Be very careful not to damage or scratch the inside surface. Lubricate the new seal with a little hydraulic oil and ease it back on, it requires considerable force but it is much more stretchy than you think.

  14. #14
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    Default Re: A Hydraulic Steering Puzzle

    Paul,

    We have a very similar steering system on our Broadblue 42 and our rudders do go out of sync when moored up or anchored for reasonable periods of time.
    Peter's explanation is correct - the seals in the rams will seal correctly at higher pressures, ie when sailing or motoring using normal steering pressures. At anchor the pressure on the seals is generally minimal and there will always be some oil that manages to by-pass the seals - strangely it always seems to go only one way - over time the rudders go out of sync. This is the main reason why any two ram / two rudder system will always have by-pass valves to allow re-alignment of the rudders.
    We can easily align ours underway in fairly calm conditions - steer straight ahead according to the rudder position indicator and then open the by-pass valve on the other rudder (rudder without position indicator), a few seconds will align the rudder and you can then close the valve.
    When stationary we can centre the steering according to the position indicator, open the by-pass on the other rudder and manually adjust to the correct position before closing the valve again. We have a plastic rod cut to the correct size for the amount of piston rod that should be extended to give central rudder position so this procedure is very easy. However it does depend on how accesible the rams are on your system to make this manual adjustment quickly and simply.
    No amount of new seals etc will cure the problem completely - it is something you have to live with on a two ram / two rudder system. Obviously a tie-bar will eliminate the problem but it could also cause excessive pressure build-up in the system because the rudders will be held in position so any oil that by-passes the seals will effectively be fighting against the tie-bar. Most steering systems with tie-bars between the rudders only have one steering ram to avoid this conflict.

    Hope that helps, Chris

  15. #15
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    Default Re: A Hydraulic Steering Puzzle

    That does help Chris, thank you.
    We have easy access to adjust the rudder without the indicator and can easily realign at anchor.
    If needed. I can also occasionally realign, as you say, underway.
    I understand what you say - its just that in our seven years we have never really had this before.
    That is what has thrown me. Also we seem to have only had it since we installed the new ram.

    At anchor here we have some surges coming in and a current slightly different to the wind angle. The monos here are rolling all over the place and putting out kedges. Leaving the bypass valve open we end up with a smaller amount out of sync - probably because the rudder is simply following the pressure on it and that is not perfectly aligned with the boat.

    On top of that i have been trying to understand why it only goes one way - always the same way!

    Your post has added to the one from Peter in reassuring me that all is really OK for the trip.

    I will have the seals replaced today on the old ram anyway but will not fit it. Just have it as a spare - its not leaking at all hence best left well alone.

    This has been a very informative thread for me.
    Safe Sailing
    Paul
    Blog: www.suliere.com

  16. #16

    Default Re: A Hydraulic Steering Puzzle

    Yeah had that problem - one isolation valve (port side) was slightly open. Easy fix.

  17. #17
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    Default Re: A Hydraulic Steering Puzzle

    We are now in Ahe Lagoon in the Pacific and for the first time in months with OK wifi.

    The rudder goes out of sync by about one degree per hour and so every 6 hours since Galapagos I am having to go down in the sugar scoop hatch and swing the rudder back. We will replace the new cylinder with the old one that now has a new sat of seals fitted because this never happened prior to fitting the new cylinder in Galapagos. This will be done n Tahiti in week or so.
    Safe Sailing
    Paul
    Blog: www.suliere.com

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