Hydraulic Steering Questions

[delmarrey]

Originally Posted by belizesailor

Interesting. I've never driven a hydraulic system that had decent feedback. What's your configuration? "Feedback" valve?

To hell with manual feed back!
I installed hydraulic gauges port and stbd right at the cylinder. I keep my wheel hydraulically locked when sailing and rely on the gauges for trim. Motoring, I just pull out the lock to make it easier to steer.

I hardly ever see more then 200 psi feed back unless I'm going over a crest. It sure makes sail trim a breeze.

When I installed my Kobelt system they sent me a form to fill out, in which they calculated the stresses and and the size of the system I needed for my boat. It worked out perfectly. I have 4.5 turns lock to lock at 70 degrees of swing. I only have a 36" wheel but I can still turn it easily in the big waves. I do wish it were more like 3.5 turns but I have a fairly large rudder that contributes to the COR.

If you need any tips on plumbing it up, I am a hydraulic mechanist. all my fitting are either NPT or JIC 37.5 degree, made of bronze or SS. The only steel in my system is the ends of the flex hose at the cylinder, only b/c I figure I'll be replacing them on occasion, and #8 fittings in SS are quite spendy. And my system has no drips! Use professional tools to do the work.

[Matt sachs]

Thanks Del. I too have 35 degree swing lock to lock. I put in 2 capline 1275V helm pumps, and the 2 cylinders pictured. I used 5/8 A/C copper with brass SAE 45degree flare fittings. The copper lines go into a brass manifold thats mounted to a rigid frame. The flex lines go from the manifold to the cylinders. The cylinders are brass with SS rams. The tiller is aluminum but they are connected with 5/8 grade 8 steel bolts and a steel washer between the aluminum and SS.( Is there is a better material than steel here) The rudder shaft is SS also, so I put a brass bushing between the SS and aluminum tiller. How does this sound galvanically?

[Matt sachs]

correction. 35 degrees from center both ways. 70 lock to lock.

[delmarrey]

Originally Posted by Matt sachs

The tiller is aluminum but they are connected with 5/8 grade 8 steel bolts and a steel washer between the aluminum and SS.( Is there is a better material than steel here) The rudder shaft is SS also, so I put a brass bushing between the SS and aluminum tiller. How does this sound galvanically?

If the bushing is a real thin plastic, it sounds OK to me. But you can use Tef-gel between the two to help prevent galvanic problems. Also the bolt, I'd coat with lithium grease or Tef-gel in case you have to disassemble. A SS bolt would be better, a steel bolt might get rusty and swell up (iron oxide) and you would never get it out, if extreme.

Mine splits in half so no problem there. But no water is supposed to get in there, hopefully! You can see it on my blog below.

[Matt sachs]

Thanks Del, pictures are always a big help. I'll post some pictures this weekend if I get it finished.

[belizesailor]

Something else to consider with hydraulics: what's your plan for emergency tiller use? Can't turn the rudder with a pressurized cylinder attached. And, at least on twin rudder/twin cylinder systems, the cylinders get out of sync sometimes, I assume you will have the same issue on a twin cylinder/single rudder system. If so you will need some way to get them back in sync.

[delmarrey]

Originally Posted by belizesailor

Something else to consider with hydraulics: what's your plan for emergency tiller use? Can't turn the rudder with a pressurized cylinder attached. And, at least on twin rudder/twin cylinder systems, the cylinders get out of sync sometimes, I assume you will have the same issue on a twin cylinder/single rudder system. If so you will need some way to get them back in sync.

From the picture above its a single rudder with twin cyl's. One gets more power from twins due to the volume/pounds per sq. in. And they can be synced since the rod goes thru both ends. Also with twins it creates even wear on the bearing.

I have a bypass valve on my system for for when I want to use the tiller.

[Matt sachs]

So with everything working I have triple redundancy. 1) I have two helms, both of which can be isolated if one fails, 2) two cylinders and they too can be isolated and the system will function with only one cylinder.3) Finally I can drop both cylinders off the quadrant and attach a tiller and steer from the cockpit.
I removed the old nylon ( I assume nylon ) bearings and need to make new ones. I have read about the problems with nylon. What is the best material?

[mikereed100]

Acetal (Delrin) is an excellent bearing material, tougher than Nylon with less water absorption.

http://www.dupont.com/products-and-s...tal-resin.html

http://www.plastic-products.com/Acet...Properties.pdf

[Matt sachs]

Thanks Mike. I have read about Delrin and think I will go with it. I ordered a foot long 4 inch rod from Granger today. Ill turn the bushings this weekend and see how it goes.