Hydraulic drive for an SPX-5??

whipper_snapper

whipper_snapper

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We have an SPX-5 autopilot with a linear actuator acting directly on the tiller.

We are consider changing the steering to a hydraulic system, does anyone know if there is a hydraulic drive unit that can be used with the SPX-5 'computer'??


I imagine that this will be far more simple and robust in use than a wheel drive or trying to bodge a bypass mechanism for the tiller drive.


Thanks
 
But the wheel drive unit would work through a horrible wobbly plastic gizmo to turn the wheel which turns a hydraulic pump!

I suspect you are right that Raymarine systems are sized such that there is not a suitable hydraulic actuator even though the work we would be asking of it is less than a typical wheel with a mechanical connection. I wonder if there any way to use a third party pump or even bodge a system with the tiller drive operating a pump.
 
It look like the smallest raymarine cause computer that can drive a hydraulic pump is the SPX-10

http://www.raymarine.com/view/?id=579

If you do change to hydraulic steering it is not recommended to drive the wheel with an autopilot or self steering due to the leakage past the cylinder seals that would need constant resetting of the wheel/autopilot connection.

I am currently adding an auxiliary rudder to my monitor self steering due to this problem.
 
Ah, interesting, that makes sense, and I guess that's why a course computer needs to know it is dealing with a hydraulic system. Well I guess we could provide a bypass valve and stay with the linear drive direct to the tiller. I worry about the increased load due to the drag on the hydraulic ram even with a bypass valve. Any idea if that is a real concern ?
 
The SPX5 can have a rudder sensor connected, which seems like it ought to solve the creep problem.

Although there aren't any compatible raymarine actuators, I believe the output is a simple voltage on a pair of wires. So presumably any suitably-rated two-way hydraulic pump could be connected.

Pete
 
prv said:
Although there aren't any compatible raymarine actuators, I believe the output is a simple voltage on a pair of wires. So presumably any suitably-rated two-way hydraulic pump could be connected.
Click to expand...

As long as it doesn't use more than 5A.
 
Yes there would be a significant increase in load on the rudder due to the cylinder ans the passage of oil around the bypass valve dependant on how close the bypass valve is to the cylinder. You will need a bypass valve any way so that the rudder can be operated by an emergency tiller (a requirement in RSA).

One possible way to use your SPX-5 to drive a hydraulic gear pump would be to add relays between the computer and the pump to carry the increased electrical load.
 
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Hmm, in use the tiller ram is chattering away constantly. I could not imagine relay contacts surviving long. I guess a sold state solution would work. We already have a rudder position indicator, not in use with the tiller ram but it could be returned. I suppose if I used a raymarine drive via some kind of amplifier it should work, I worry that the characteristics of the pump are so different from the motors it expects that it may not be happy.......No use asking Raymarine that's for sure!
 
whipper_snapper said:
Hmm, in use the tiller ram is chattering away constantly. I could not imagine relay contacts surviving long. I guess a sold state solution would work. We already have a rudder position indicator, not in use with the tiller ram but it could be returned. I suppose if I used a raymarine drive via some kind of amplifier it should work, I worry that the characteristics of the pump are so different from the motors it expects that it may not be happy.......No use asking Raymarine that's for sure!
Click to expand...

Frequent activation of the pump would be more likely to show up any reliability problems of of using relays.*
However the AP should be adjusted so as not to be continuously chattering - this bad for the linear drive's longevity or pump's for that matter as well as increasing the average power consumption. Are you perhaps expecting it to steer too straight a course?

Its possible a hydraulic system may be slower to respond than a linear drive but with a rudder ref unit connected, and tweaking of the AP settings - rudder gain etc, it should work.
* My old hydraulic analogue Cetrek AP uses a couple of heavy duty relays (contactors) and is still going strong after 30years.
 
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whipper_snapper said:
We have an SPX-5 autopilot with a linear actuator acting directly on the tiller.

We are consider changing the steering to a hydraulic system, does anyone know if there is a hydraulic drive unit that can be used with the SPX-5 'computer'??


I imagine that this will be far more simple and robust in use than a wheel drive or trying to bodge a bypass mechanism for the tiller drive.


Thanks
Click to expand...
I think that you should keep the primary steering system as it is and substitute the present mechanical linear drive with an hydraulic ram fed by a pump. This is in fact the most sensible solution.
The quickest solution is to go for an hydraulic ram with a constant running pump often sold as a unique integrated system. The autopilot will actuate low amp solenoid valves and the clutch output will control an integrated by-pass valve. You may find such units quite easily for example from Raymarine, Simrad etc.
I am afraid nothing made for sailing will be cheap but you may shop around for items not intended for the marine market: they are pretty the same.

Daniel
 
danielefua said:
I think that you should keep the primary steering system as it is and substitute the present mechanical linear drive with an hydraulic ram fed by a pump. This is in fact the most sensible solution.
The quickest solution is to go for an hydraulic ram with a constant running pump often sold as a unique integrated system. The autopilot will actuate low amp solenoid valves and the clutch output will control an integrated by-pass valve. You may find such units quite easily for example from Raymarine, Simrad etc.
I am afraid nothing made for sailing will be cheap but you may shop around for items not intended for the marine market: they are pretty the same.

Daniel
Click to expand...

Its fine using a constant running pump if you have plenty of battery capacity otherwise they are not viable.
 
danielefua said:
I think that you should keep the primary steering system as it is and substitute the present mechanical linear drive with an hydraulic ram fed by a pump. This is in fact the most sensible solution.
Click to expand...

Is it the most sensible solution? As I read it, the OP has a cockpit-mounted electric ram working his tiller. Maybe I'm mistaken.
 
danielefua said:
I think that you should keep uthe primary steering system as it is and substitute the present mechanical linear drive with an hydraulic ram fed by a pump. This is in fact the most sensible solution.
The quickest solution is to go for an hydraulic ram with a constant running pump often sold as a unique integrated system. The autopilot will actuate low amp solenoid valves and the clutch output will control an integrated by-pass valve. You may find such units quite easily for example from Raymarine, Simrad etc.
I am afraid nothing made for sailing will be cheap but you may shop around for items not intended for the marine market: they are pretty the same.

Daniel
Click to expand...

The present primary steering stem is pants. It involves Lois of string, turning blocks etc and is stiff and horrible to use. The autopilot with the mechanical linear ram is very nice, except that it's total throw is less than the manual system provides. However it seems unlikely that we can keep it with a hydraulic primary steering system.
 
whipper_snapper said:
The present primary steering stem is pants. It involves Lois of string, turning blocks etc and is stiff and horrible to use. The autopilot with the mechanical linear ram is very nice, except that it's total throw is less than the manual system provides. However it seems unlikely that we can keep it with a hydraulic primary steering system.
Click to expand...

So you want to get rid of the existing steering system and replace with a hydraulic one, and then fit an electric pump so an AP can steer the boat?
This wasn't really apparent from your OP and the expense will be considerable just to install a manual hydraulic system, apart from the expense of changing the SPX5.
 
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The reduced throw won't be a problem, we never go near the stops with the hydraulic steering on autopilot, I wouldn't want that going stop to stop! I don't think I've seen even 15 degree rudder on the autopilot.
 
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