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Thread: Can Hydraulic Steering Systems Have Non-Hydraulic Autopilots?

  1. #1

    Default Can Hydraulic Steering Systems Have Non-Hydraulic Autopilots?

    Offshore multihulls should build as much redundancy into their steering systems as possible, and ease of repair is an important consideration in selecting the type of autopilot that you install.

    When I was in New Zealand, I met a husband and wife sailing team on a 48 foot catamaran who experienced a hydraulic autopilot failure on their hydraulic steering system when sailing from New Caledonia to New Zealand. Apparently the hydraulic motor failed early on in the trip, and repairs could not be done.

    What was supposed to be a five or six day trip turned into a thirteen day nightmare. By the time they arrived back in New Zealand, they considered putting their catamaran up for sale.

    Without the hydraulic autopilot, they hand steered during daylight hours, and at night they drifted at sea losing some of the progress they had gained during the day.

    Ever since this incident, I have wondered whether they should have an non-hydraulic electric autopilot like our linear drive Autohelm 7000 connected directly into the steering quadrant. It is accessible, easy to repair, and if there is a major failure in the hydraulic steering, you can still carry on with a non-hydraulic autopilot.

    I don't understand the way hydraulic steering systems and autopilots are set up, but it seems like a good idea to put some additional redundancy into the steering by having a non-hydraulic autopilot to protect against hydraulic disasters offshore.

    Is it OK to use a non-hydraulic autopilot on a hydraulic steering system? Would a non-hydraulic autopilot offer additional redundancy to a steering system, especially in the event of a hydraulic failure offshore?

  2. #2
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    Default Re: Can Hydraulic Steering Systems Have Non-Hydraulic Autopilots?

    Quote Originally Posted by Maxingout View Post

    Is it OK to use a non-hydraulic autopilot on a hydraulic steering system? Would a non-hydraulic autopilot offer additional redundancy to a steering system, especially in the event of a hydraulic failure offshore?
    I don't think so (to both questions), To use a non-hydraulic A/P would mean either disconnecting the hydraulic steering system and connecting the A/P directly to the rudders every time you wanted to use it OR if you're thinking of a 'wheel system' the input from the A/P is transmitted to the wheel then to the hydraulic system and then to the rudders.
    On my BB385 I can disconnect the hydraulic system if it fails, but then I have to purge the hydraulic system (easy operation)and make steering inputs through an emergency tiller. This is a large device and it's not possible to fit an A/P system to it.

  3. #3
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    Default Re: Can Hydraulic Steering Systems Have Non-Hydraulic Autopilots?

    You can easily set up an electric drive system instead of an hydraulic one. Install a by-pass valve across the hydraulic ram, if you don't want to bother disconnecting it. The electric actuator can then be connected to one of the ruddder arms, the system powered up and you can be up and running. Connect the rudder position sensor to the electric drive controller, adjust and tune the settings and enjoy...
    (this is if your 2 autopilots can use the same sensor)

    If your boat has a cross bar between the 2 rudders, you can mount a bracket on the cross bar, in a locker, and mount the backup system to it after disconnecting/by-passing the hydraulic ram.

    Alan

  4. #4

    Default Re: Can Hydraulic Steering Systems Have Non-Hydraulic Autopilots?

    A wheel pilot would have done the job in the example mentioned. The actual steering system was still working, just the hydraulic pump motor had failed.

    Also, in their instance, where the failure was early in the trip, I would have though turning back to New Cal and replacing the drive would have been more sensible than pressing on.

  5. #5

    Default Re: Can Hydraulic Steering Systems Have Non-Hydraulic Autopilots?

    I don't understand why they didn't return to New Caledona, but I know they were really discouraged by the time they arrived back in Whangarei.

    This incident always confused me about hydraulic steering systems. It seems like there would have been some type of redundancy built in to the steering system - spare parts to make repairs - something to alleviate their misery.

    I don't know how hard it is to replace a hydraulic pump offshore even if you have a spare part.

    We always carried a complete spare Autohelm 7000 on board Exit Only, and whenever we experienced a failure, we had it fixed within 1 or 2 hours. Sometimes it was fixed in minutes by swapping a component out.

    If you do have the spare motor for a hydraulic autopilot, would it be an easy fix to do offshore?

  6. #6
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    Default Re: Can Hydraulic Steering Systems Have Non-Hydraulic Autopilots?

    I have considered carrying a cheap tillerpilot in case of autopilot failure. Mount it on the tiller arm, "set it and forget it". Adjustments would be a pain but better than hand steering. On a dual ram system like mine only one rudder would be in play but this should be adequate to get to port.

  7. #7

    Default Re: Can Hydraulic Steering Systems Have Non-Hydraulic Autopilots?

    Quote Originally Posted by mikereed100 View Post
    I have considered carrying a cheap tillerpilot in case of autopilot failure. Mount it on the tiller arm, "set it and forget it". Adjustments would be a pain but better than hand steering. On a dual ram system like mine only one rudder would be in play but this should be adequate to get to port.
    Anything is better than having to hand steer day and night. It's hard for crew members to steer a straight course, and when they lose concentration at a critical moment, bad things happen.

    Our voyage would have been real work without our Autohelm.

  8. #8

    Default Re: Can Hydraulic Steering Systems Have Non-Hydraulic Autopilots?

    Quote Originally Posted by Maxingout View Post
    I don't understand why they didn't return to New Caledona, but I know they were really discouraged by the time they arrived back in Whangarei.

    This incident always confused me about hydraulic steering systems. It seems like there would have been some type of redundancy built in to the steering system - spare parts to make repairs - something to alleviate their misery.

    I don't know how hard it is to replace a hydraulic pump offshore even if you have a spare part.

    We always carried a complete spare Autohelm 7000 on board Exit Only, and whenever we experienced a failure, we had it fixed within 1 or 2 hours. Sometimes it was fixed in minutes by swapping a component out.

    If you do have the spare motor for a hydraulic autopilot, would it be an easy fix to do offshore?

    Replacing a hydraulic drive wouldn't neccessarily be too difficult if you have a spare. Bleeding the air out would be the hardest bit, depending on your system. A little prior planning could greatly simplify this too.

    But even better, if you have a spare hydraulic drive you could have it already plumbed in, ready to go. Just a matter of swapping the wiring over, (which could easily be quick connections) opening some valves and it's working. It could be done in less than a minute.

  9. #9
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    Default Re: Can Hydraulic Steering Systems Have Non-Hydraulic Autopilots?

    YES. By isolating the hydraulic ram on one side and using the emergency tiller- connect a push pull tiller pilot like a Raymarine 1000/2000. response rate is not great but it works. (This covers a hydraulic failure - loss of fluid, and also a hydraulic autopilot failure.)

  10. #10
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    Default Re: Can Hydraulic Steering Systems Have Non-Hydraulic Autopilots?

    Some folks put a trim tab on a rudder and control that with a tiller autopilot. A big boat could ship an emergency rudder on the bridgedeck to work with a tiller autopilot. You'd use the permanent rudders to balance the boat, and then the auxiliary rudder could make minor adjustments. In my experience, the main thing likely to fail in a hydraulic system is the seals, so carry spares. Of course, checking our user reviews of autopilots is a must before you buy one. WH is supposed to be bulletproof.
    Currently concentrating on http://earthnurture.com .

  11. #11
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    Default Re: Can Hydraulic Steering Systems Have Non-Hydraulic Autopilots?

    An ordinary, non-hydraulic wheel pilot can be used with hydraulic steering so long as it is connected to a rudder position indicator (otherwise the slight 'give', or 'sponginess' in the steering leads to changes in dead-center and confuses the brain of the autopilot). Having said that, hydraulic systems are very robust and reliable - lets face it, they have been used in large ships for over a century.

    Brad

  12. #12

    Default Re: Can Hydraulic Steering Systems Have Non-Hydraulic Autopilots?

    After this thread I actually did install a second hydraulic autopilot pump. It's all plumbed in, ready to go. Just a matter of flicking a switch to change over. I made the second pump slightly bigger too, so if in heavy conditions the normal pump isn't coping very well I can switch over then too.

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