Boating Straight

[FF]

Follow Da Book and bleed the system.

[Anode]

FF wrote - "Follow Da Book and bleed the system."

+1

[Nomad Willy]

One of the things I did when installing my hydraulic steering system was route the hose so that (from the ram on the cockpit deck) the hyd hose goes down 2.5' in the lazerette. Then the hose is routed all the way to the helm at a nearly constant angle and all the way upward. No dips downward. Any air bubble in the system quickly makes it's way to either the ram or the pump where it can bled off. In 3 yrs I've added less than a half a cup of fluid to the system. Over the last year I;ve added none. In very calm water after directionally stabilizing the boat at cruise speed I can very carefully turn the helm (past the 3/16" slop) 3/16" (left or right) and the boat responds correctly. Since air is compressable any air in the system would make the system feel like it was made w rubber bands. Any high spot in the hyd hose will trap air and that could be causing some of these steering problems. I would suspect many hyd steering systems could be installed by quite unskilled people so here's another thing to check to make steering as good as it can be.

Eric

[Tom.B]

Hey cool! Thanks Eric.

I have two questions on that subject then:

Would those same air bubbles allow movement of the rudder from the external force of the water that might not be felt in the helm?

When I check the system, I was just going to have the Carbon Wife Unit move the wheel slightly (as someone noted above). If I do feel movement in the ram or on the rudder arm, does that effectively prove there is no air in the system?

[Codger2]

When I bought my boat it was about a year old with 67 hours on it. The steering was terrible and the PO showed me where he had an "eye dropper" and a small bottle of steering fluid positioned close to the helm for "filling" the system. I retained the services of a San Diego firm that specializes in steering systems and they checked the plumbing for leaks and bled the system like never before. While I was cranking the helm stop to stop, they were at the ram bleeding the air. While I added fluid at the helm with a rather large hose,* they continued to bleed, monitoring a clear plastic tube they had installed at the ram bleed screw for the process. When absolutely not one bubble was visible, the process was deemed completed, the clear tube removed and the system returned to its original state. Why this long winded post on bleeding? This company told me that the "books" that come with these systems are totally "inept" in their attempts to villainize* "air in the system." The tubing in a system can look like a "corkscrew" and if all the air is removed, the steering will work perfectly! Such was the case for me. A problem that plagued the PO, and probably contributed to his selling an otherwise fine boat, has been absent for 4 years. My auto pilot works much, much better and I have not added a single drop of steering fluid since said process was completed. End of rant.

[Marin]

Seahorse's description of how to properly bleed a hydraulic system is worth paying attention to. Whether it's a boat, vehicle, bulldozer, or plane, hydraulic systems can have all sorts of ways of trapping and holding air even if the person doing the bleeding thinks they are doing it right. Some hydraulic line configurations can conspire to make it almost impossible to remove all the air unless one gets almost violent about it.

On the landplanes I used to fly the hydraulic brake lines were bled backwards, using a pump and a fitting that attached to the slave cylinder at the wheel and forced the fluid backwards through the line to the master cylinder. I don't know if this method is ever used on boat steering systems but it was very effective on the planes.

Air in the iine can allow the rudder to move a bit "on its own" because the air in the line can be compressed by the rudder's movement against the steering ram which in turn will move until the air in the line is compressed.

While I guess it's certainly possible you could have gotten air in the system coincidentally with changing the shape and balance of the rudder, the fact you had no steering issues before you changed the rudder and now you do would indicate to me that the culprit is the new shape, size, balance, etc. of the rudder itself. While rudders look simple enough I would think their design is faiirly deliberate with regards to the design of the hull, the thrust being developed by the prop(s), the ratio of area forward and aft of the rudder's pivot point, and so on.

[Tom.B]

I would normally agree, but the only mitigating factor to that theory is that when I changed it, I had owned the boat all of five months. So, as you might understand, it may NOT have handled perfectly prior to the change. I just don't know. Still, I think that the change in shape and size IS the problem, that it, if it's really a problem at all and not just the way she handles or it's just in my head. Finally, it actually is better at slower speeds when it's critically important. So even if I don't reverse it, there are advantages to the adjustment.

[ralphyost]

If you really want to make your boat turn better at slower speeds, add an articulated rudder. GOOGLE it.
Here is one guy who did it
http://www.mysticrudder.com/id4.html

When we had our family run tugboat business, my dad converted the rudder of one of our tugs into an articulated rudder by welding on angle iron. Here is his drawing
http://tinyurl.com/2uwajjm
and here is the rudder on the boat
http://tinyurl.com/388h2am


R.


-- Edited by ralphyost on Wednesday 25th of August 2010 02:21:14 PM

[AllanY]

I agree with Peter B
I think the leading edge on the rudder may be excessive however the trailing edge should give better steering.

Do you have a photo??

The leading edge balances the rudder and the other effect is to give better steerage when reversing
This is the first area I would be looking at.
A maring engineer or boat designer should be able to throw some light on the problem.

Allan

[Bendit]

I also agree with Peter B and Allan Y,
You've got too much balance, i.e. too much ahead of the rudderstock. This makes the rudder supersensitive and it will be unstable. A bit extra on the trailing edge won't hurt and might help a bit. I suggest you remove the bit you added on the front and leave the trailing edge as it is.

[Marin]

AllanY wrote:

The leading edge balances the rudder and the other effect is to give better steerage when reversing

Actually in addition to physical balance, the whole idea behind a pivoted rudder is that the portion of the rudder forward of the pivot point, the part that actually moves out in the opposite direction of the turn, is*to reduce the pressure or force*needed to turn the rudder.* The water hitting this smaller forward*portion of rudder provides a force that helps turn the rudder in the direction of the turn.* So less force is needed at the helm, or less force is required by the hydraulic system.

Now rudders that are hinged directly to the end of the keel don't have this feature.* The*whole surface of the rudder*has to be moved out against the force of*the water flowing past it.

But if the rudder is a balanced*pivoted rudder (or a spade rudder on a twin) there is, I suspect, a formula or two that governs the ratio of surface area ahead of the pivot point to the surface area aft of it.*

Too*much surface area forward and the steering can actually be overcome by the force*trying to pivot the rudder and you (or the hydraulic system) will have to "hold it back" from going too far over.* Too little surface area aft of the pivot point and you'll have to add more steering pressure to move the rudder over.* The correct ratio will yield a neutral steering effort with the rudder being easy to put over without having to add much*force to move it or any force to*hold it back.

Obviously the forces will change with the boat's speed but if you get that ratio*wrong, you or your steering system will be doing more work than necessary at cruise speeds.* Or the boat may start hunting as the rudder is moved around by unbalanced forces.

The steering on our GB with its two pivoted spade rudders is absolutely neutral.* It requires no change in effort to move them near their center of travel as it does at the ends of their travel when underway.* And if you put the rudders over into a turn, even a fairly sharp turn, and let go of the wheel, the wheel just sits there.* This is with cable-chain steering.* The mechanical steering ratio tends to resist backfed forces, so that's some of it.* But the point is that the design of the rudders was carefully calculated to minimize the force needed at the wheel.

I believe it is much more than an "eyeball" art to design the right rudder for any given boat.

-- Edited by Marin on Wednesday 25th of August 2010 06:20:29 PM

[Peter B]

Absolutely right Marin, and many times after following similar discussions re the issues which can arise with hydraulic steering, I am often pleased that my vessel, like yours, has chain & rod/cable steering. However, to Gonzo, I would strongly urge the proper purging process be followed as described by Walt, even if it needs an expert to do it, so there is absolutely no air in the system before having anyone attack his rudder again, is case it is air in the hydraulics, and not the rudder balance.* If there is no improvement after that, then it has to be a rudder balance issue, as long as there is not excessive play (ie wear), in the rudder bearings.* A good wiggle of the rudder from below when out of the water (before hacking into it) should reveal if that is an issue.


-- Edited by Peter B on Thursday 26th of August 2010 05:53:48 AM

[Anode]

Installation instructions for my Wagner 700 series hydraulic steering recommends that it be plumbed*entirely*with*copper tubing (vs hose)*to a short flex hose at the cylinder to prevent instability in the steering system. That's how sensitive they are.

[Tom.B]

The point of the leading edge addition was a late adjustment. The yard where the work was done suggested we add the same ratio to the fore as aft to prevent extra stress on the bearing/bushing/stuffing box. We originally wanted to make the additions smaller, but like I said, the steel stock the welder had that was the same-ish thickness was no smaller than 1". So 4" was added aft.

[Nomad Willy]

Gonzo,Looks to me like you should cut off most or all the leading edge addition. You say it's steel.
When the boat's out just burn it off w OA cutting torch.
Another thought from my guest from Washington State (BYC) is to disconnect the ram rod end and push and pull the rudder horn thereby checking for lateral movement that would allow the rudder to move without a corresponding movement of the helm.


Anode,
I was told this also when I expressed my displeasure about the friction of the hyd steering. I bought the "Capilano" helm pump (much larger unit than my boat required) thinking that a large pump and large dia tubing would make for very light steering * * .....NOT so. Then they told me I needed copper tubing but I've talked to numerous others that say copper tubing is a maint nightmare. I think the reason the hyd steering has high friction is that all the seals exert significant pressure on the cylinder and rods. My larger components have larger area and bigger seals and hence more friction. If I had bought a system w small components my steering would have much lighter feel. By the way I didn't use marine hyd hose. I used large dia industrial hose * *...the kind found on equipment like back hoes and excavators. Shot myself in the foot but when I'm out on the outer coast in the nasty those big beefy steering components are a comforting thought.

[jleonard]

Then they told me I needed copper tubing but I've talked to numerous others that say copper tubing is a maint nightmare

How so? I have the original 1983 copper tubing in my Albin. It looks good (where I can see it) and everything works fine. I have maybe 2 feet of hyd hose* from the uniflow valve to the cylinder, and I plumbed in the new autopilot pump with hydraulic hose (old non working pump was hard plumbed).

[Datenight]

Chip,

That is what we have. Copper tube with a short length of hose at the ram.

Rob
37' Sedan

[C lectric]

I too have copper lines with just the last connection to the cylinder a hydraulic hose.
The boat is 33 yrs old.*** I did some repairs about 12 years ago but not to the copper itself, but rather to the poorly done flares.** They are now all double flares and leak free.

One of the helm pumps is showing signs of a leak so that repair may be upcoming soon.*

The Wagner book strongly suggested the copper to eliminate expansion of the hoses.

[Tidahapah]

Yeah,
Hydrive here in Australian reccomend the same, HP copper pipe all the way except at ends to ram and Octupuss pump short flex hose.
I installed mine 15 years ago and no probs.
A little leakage at the pump but easily tightened.

Benn

[Tom.B]

Hey y'all,

Sorry to dig up another old thread of mine, but I wanted to touch on this subject again as we are getting ready to pull Skinny Dippin' out for some routine work. I'd like, once again, to ask your opinion based on the pics I am posting. (I found them just the other day. Figured it might help you see my issue.)

I am now back on the side of doing nothing, even though I have just changed sides after seeing the pics. My memory thought the rudder was closer than it appears to be in the pics. Add to the fact that I don't know any other boat but this one. I spoke with someone with way more experience than I and he said, all single-screws wander around. He did qualify it by saying that it is more of a problem with the CHB trawlers because of their smaller rudder, but unless you can make it, and the screw, MUCH bigger, it's going to happen. I won't be able to go dead straight without any helm input very often.

One thing he said to try was to remove the zincs and see if that helps... I will try that in the future. I will also try what others mentioned here and bleed the hydro steering system. Perhaps explore slightly heavier oil in it.

*NOTE* The additions are not quite as thick as the original rudder. 1/16th smaller, or so.

Anyway... chack out the pics... See if I should just leave it alone or cut off the addition(s).

Thanks,
Tom-