Catamaran hydraulic steering problem

[chrisr]

here's one for anyone with hydraulic experience - esp multi ram catamaran steering...

we have hydraulic steering, with seperate ram on each tiller head. stupidly i recently let the hydraulic fluid in our steering get low...very low

i've now topped it up again however find there is now about 20deg diff between the two rudders

i'm guessing that realignment is a matter of opening a bleed screw, and forcing a ram back, so that both rudders are in alignment again

is it really that simple ?

anything to particularly watch out for ?

(btw, hydraulics and i have a very poor relationship...it hates me and i hate it. never seems to work for me the way it's supposed to...)

cheers,

[atoll]

assuming you have got all the air out of the system to start with.
there is an easy way to adjust the ram without loosing oil or introducing air into the system,which is the same as you would do when bleeding the brakes on a cars breaking system

using some clear tube and and a couple of jam jars fill the jars half full with fluid,then attach the tubes to the bleed screw on both sides of the ram .
open one of the bleed screws and turn the helm to evacuate the air from the tube on one side.
once their is no air in the tube,you can open the other side bleed screw and centralise the ram by forcing over the rudder ,fluid will be sucked up in one jar and pushed out in the other jar.
close bleed screws once alignment is set,job done!

you can use the same process if you have introduced air into the system,except you need to turn the helm and fill oil at the helm with a bleed screw open untill no more air exits the ram,do this in one direction,then in the opposite wit the other side bleed screw open to evacuate air from the system

[chrisr]

Originally Posted by atoll

assuming you have got all the air out of the system to start with.
there is an easy way to adjust the ram without loosing oil or introducing air into the system,which is the same as you would do when bleeding the brakes on a cars breaking system

using some clear tube and and a couple of jam jars fill the jars half full with fluid,then attach the tubes to the bleed screw on both sides of the ram .
open one of the bleed screws and turn the helm to evacuate the air from the tube on one side.
once their is no air in the tube,you can open the other side bleed screw and centralise the ram by forcing over the rudder ,fluid will be sucked up in one jar and pushed out in the other jar.
close bleed screws once alignment is set,job done!

you can use the same process if you have introduced air into the system,except you need to turn the helm and fill oil at the helm with a bleed screw open untill no more air exits the ram,do this in one direction,then in the opposite wit the other side bleed screw open to evacuate air from the system

thanks - doesn't fill me with confidence as i could write books on the problems i've had bleeding car & motocycle brakes

still, we're not going anywhere so guess i might as well have a go...

cheers,

[atoll]

Originally Posted by chrisr

thanks - doesn't fill me with confidence as i could write books on the problems i've had bleeding car & motocycle brakes

still, we're not going anywhere so guess i might as well have a go...

cheers,

the jam jar trick makes it really easy to get the air out of the system,just make sure the tubes stay submerged in the oil,same with the helm just make sure you keep topping up reservoir

[Bruce K]

There should be a ball valve (which is normally closed) somewhere in the tubing between the two rams; open it, align the rudders manually, then close it. Job done, assuming you have got ALL air out of the system.

[atoll]

Originally Posted by Bruce K

There should be a ball valve (which is normally closed) somewhere in the tubing between the two rams; open it, align the rudders manually, then close it. Job done, assuming you have got ALL air out of the system.

+1,although it sounds like there has been air introduced into the system.

opening the crossover valve/s if there is one will also allow you to bleed that part of the system back to the helm before you need to bleed any air out of rams

[chrisr]

Originally Posted by Bruce K

There should be a ball valve (which is normally closed) somewhere in the tubing between the two rams; open it, align the rudders manually, then close it. Job done, assuming you have got ALL air out of the system.

hmmm

that sounds interesting. not seen such a valve yet but shall go hunting tomorrow n see what i can find

thanks !

cheers,

[mikedefieslife]

I have twin rams. I have a valve in between the two that when on allows me to freely adjust one of the rudders to re-centre it.

Here's one from SVB.

https://www.svb24.com/en/vetus-by-pass-valve.html

[Chotu]

Something to google when looking for this valve is “catamaran liquid tie bar”

You’ll find it right away.

[blubaju]

Originally Posted by Bruce K

There should be a ball valve (which is normally closed) somewhere in the tubing between the two rams; open it, align the rudders manually, then close it. Job done, assuming you have got ALL air out of the system.

Correct, everything else would be total stupidity of the installer, if factory made, return the boat, you do not know what else they built in.

In my first cruising cat I had hydraulics too, my second one the designer asked why I want to carry so much useless weight. Pull-pull dyneema, 5mm was the very lightweight solution, the quadrants carbon fiber, easy to repair in the most remote place, but never failed in the last 10 years. Dyneema for the low stretch

[Chotu]

Originally Posted by blubaju

Correct, everything else would be total stupidity of the installer, if factory made, return the boat, you do not know what else they built in.

In my first cruising cat I had hydraulics too, my second one the designer asked why I want to carry so much useless weight. Pull-pull dyneema, 5mm was the very lightweight solution, the quadrants carbon fiber, easy to repair in the most remote place, but never failed in the last 10 years. Dyneema for the low stretch

Could you share with us how this pull/pull dyneema steering system is set up?

At the wheel, through the boat and especially how you divide the action into both hulls and rudders?

This has been a sticking point for me for a long time. I currently have push/pull cable steering and it’s too sloppy. I was going to upgrade to hydraulic but if I could figure out a pull/pull...

[atoll]

Originally Posted by Chotu

Could you share with us how this pull/pull dyneema steering system is set up?

At the wheel, through the boat and especially how you divide the action into both hulls and rudders?

This has been a sticking point for me for a long time. I currently have push/pull cable steering and it’s too sloppy. I was going to upgrade to hydraulic but if I could figure out a pull/pull...

i have dynema pull pull system ,(but with a cross bar).
the dynema from the helm which has a bike chain sproket that the dynema joins to, it then leads to a double pulley below the helm, the dynema then leads to the transom where there are 2 more double pulleys at 90 degrees then to single pulleys outboard on either hull,then back to the middle where the ends clamp onto the cross bar with tensioning lashings.

you could have a dynema cross link instead of the cross bar,but on the prout space is limited on the outboard side to the rudder lever arm ,and is impractical to have a dynema link

[blubaju]

Originally Posted by Chotu

Could you share with us how this pull/pull dyneema steering system is set up?

At the wheel, through the boat and especially how you divide the action into both hulls and rudders?

This has been a sticking point for me for a long time. I currently have push/pull cable steering and it’s too sloppy. I was going to upgrade to hydraulic but if I could figure out a pull/pull...

no dividing, double installation all the way from the steering wheel shaft to the quadrant. Advantage, even in the unlikely case one line has a problem, disconnect and there is still control with the other one, as long as you do not push back, no problem, of course you want to block the rudder and then repair whatever failed. But I am lucky, last 10 years no problem.

Securing on the steering wheel shaft: 4 windings each and a set screw in the center. Rope tension is done at the quadrants (at my boat), but you might use line deflection anywhere.

Autopilot drives the steering wheel shaft too, a stainless motor bike chain connects to the
http://www.jefa.com/steering/product...ocket-menu.htm

In case of lacking space at the steering wheel connect the lines to the autopilot-chain. Risk is a broken chain, you might loose all control, but it is very unlikely to happen. While the original 5/8" stainless chain is expensive, same in ordinary steel is a cheap spare part

No conduits, sheaves only, well there are conduits, straight PVC watersystem tubes, but for rope protection only, after all 2x20m steering ropes on a cruising cat you want to protect

Hope I could help ;-)

[out42]

Others have pointed the way, and I had the same problem but didn't need to bleed it all. I simply changed the fluid from ATF to Hydraulic oil by draining off the ATF down at the ram end and filling the reservoir with hydraulic oil 20 grade. You can get round the bleeding problem as follows:
you must find the cross-connect valves which allows the rudder arm to move freely. It will be near the tiller-head somewhere on both sides. They will exist!

Make sure the reservoir is full, open the cross-valves, turn both rudders by hand fully to one side. Close the cross-valves. Using the helm and making sure the reservoir doesn't run low, turn the rudders to the other side. Close the cross-valves and turn the rudders back by hand again. Repeat. After you have done that 2-3 times, any air will have gone through both ram systems and bubbled out in the reservoir. Easy to do and reasonably quick. Can be done in the water as you can turn the rudder using the tiller arm with maybe a lever.


Only had to do it once and it worked beautifully. The only catch is that you may have to bleed the hydraulic autopilot pump but that will usually bleed itself under gravity if you open its bleed valve.


I find hydraulics just great. Reliable and tough but you do need to say hello to them once each season, or they get grumpy! Not many other things are as reliable.

[chrisr]

ok...valve located. tucked away right close to the port ram

shall make it tomorrows job to pit whats left of my sanity against the hydraulic gremlins. wish me luck...

cheers