Self centering rudder

[coreychamness]

Do other tugs experience this? If I turn the helm (either flybridge or pilothouse) right or left full rudder and leave it there, the RUDDER will gradually shift back toward center. This is not with the autopilot engaged or even on. It does not move swiftly but it will definitely migrate back toward center with no movement of the helm at all. I believe the rate of return to center is related to speed since the force on the rudder is greater at higher speed

Corey

 

[LADYBUG TOO]

Generally speaking rudders are dynamically balanced so that you do not need as much force to turn them. That being said, the dynamic force is limited so that the rudder does not, by itself, turn hard to port or starboard. The shaft is located forward of the center line of the rudder between 1/3 and 1/4 of its width from the leading edge. This allows some boost while steering but will also return the rudder to a near neutral position depending on the speed of the vessel and the mechanical friction within the steering system. Some helms have a "friction adjustment" that will negate the return to center force and leave the rudder in the last position set at the helm. My old boat would track a straight line unless I turned the helm. Our R-29 tends to wander a bit at slower speeds and doesn't much like a quartering sea. Probably TMI but that's a problem I have....running my mouth.

Pat
Ladybug, Too

 

[coreychamness]

So I can't tell from your response if you are saying your rudder returns itself to center/neutral without helm input or not.

 

[LADYBUG TOO]

Sorry. It will center most of the time but I don't trust it to center.

Pat

 

[SGIDAVE]

Sorry. It will center most of the time but I don't trust it to center.

Pat

Hello Pat, Corey, Others,

I must not understand a hydraulic steering system.

Corey's original post was about rudder movement in the absence of helm or AP input.

If you turn the rudder, it CANNOT move back unless the helm is turned OR the AP pump moves hydraulic fluid OR there is AIR in the system.

I understand what you say about forces on the rudder trying to "center" it. But, unless one of the 'pumps' (helm or AP) works to move hydraulic fluid, the rudder shouldn't move...should it?

I don't observe the rudder moving back to center SPONTANEOUSLY on my little tug.

Could there be a "leak" in the helm pump that lets fluid through slowly and eventually lets the rudder center itself? This doesn't seem plausible as there are "stops" in the rotation of the steering wheel...so, it you turned hard STB...then the rudder "centered" itself without movement of the helm...you couldn't turn the wheel to STB any further since it is already up against it's stop. YIKES!

WHAT could be going on here? Air in the system?

Fair winds and sound steering systems,

David

 

[LADYBUG TOO]

David,

I think you are correct. The hydraulic system should prevent the rudder from centering unless there is a fluid issue like air in the system which seems to have been the reason for my helm movement.

Pat,
Ladybug, Too

 

[coreychamness]

David,
That is why I am asking if others experience this. I have driven vessels from dinghy to the Sailing barque CGC Eagle and never experienced what I am now with my R-31 and thinking it is normal. The steering system itself is not pressurized per se - there is no steering pump. The auto-pilot has a separate pump and operates upon the system when energized.

Corey

 

[Osprey]

The key components in the Ranger steering system are a steering wheel connected to a pump, hydraulic lines, and a cylinder connected to the rudder arm. The steering pump does not have "stops". However, the rudder cylinder has a travel limit which the helm person senses as a stop - hard to port or hard to starboard. Now suppose while under way we turn the wheel until the rudder cylinder is forced to the limit of its travel. Further, suppose that the is a slight seal (valve) leak in the steering pump. This leak would allow some oil back flow which, in turn, would allow the cylinder and rudder to move towards a self centering position. As this centering occurs the helm can now be further turned to reestablish the desired rudder angle. I have sensed that this occurs to a very slight extent on my boat for "normal" steering maneuvers but I have never tried to continuously run fast with a hard over helm.

 

[coreychamness]

The possibility of leaking around the seal is basically what I am thinking. This condition was discovered through the necessity of continuous rotation of the helm (wheel) to starboard to maintain course.. The requirement for constant starboard rudder (similar to weather helm on sailboat) would not surprise me but the need to continuously spin the wheel does. The running fast with hard over helm was just an experiment to see if this occurred in both directions and forcing an extremely case for illustration while observing the rudder.

Corey

 

[coreychamness]

A final update on what was a problem that took almost a year to troubleshoot and solve.

Our R-31 required nearly continuous attention to keep steering to the right in order to go straight. It also turned far better to port than to starboard. If you put the helm hard over to starboard, it would gradually ease back to center and then begin turning left. We used the machine to remove potential bubbles from the hydraulic fluid, we replaced both steering pumps (flybridge and main helm), we corrected some factory mistakes with incorrect hydraulic line plumbing. All of these combined to lessen the problem but it still remained. The final remedy - we bypassed the auto-pilot hydraulic pump and the problem stopped. As it turned out, the autopilot was causing a small, but continuous left turn. We replaced the autopilot pump, used the machine to purge bubbles and returned to service. The autopilot was both a curse and a blessing for the past year. It cursed us with the need for continuous input but it also made itself essential since it was the only way to travel long distances because it didn't seem to mind continuously turning.

Thanks to Pocket Yacht in Maryland for their perseverance in troubleshooting!

Corey

 

[walldog]

A final update on what was a problem that took almost a year to troubleshoot and solve.

Our R-31 required nearly continuous attention to keep steering to the right in order to go straight. It also turned far better to port than to starboard. If you put the helm hard over to starboard, it would gradually ease back to center and then begin turning left. We used the machine to remove potential bubbles from the hydraulic fluid, we replaced both steering pumps (flybridge and main helm), we corrected some factory mistakes with incorrect hydraulic line plumbing. All of these combined to lessen the problem but it still remained. The final remedy - we bypassed the auto-pilot hydraulic pump and the problem stopped. As it turned out, the autopilot was causing a small, but continuous left turn. We replaced the autopilot pump, used the machine to purge bubbles and returned to service. The autopilot was both a curse and a blessing for the past year. It cursed us with the need for continuous input but it also made itself essential since it was the only way to travel long distances because it didn't seem to mind continuously turning.

Thanks to Pocket Yacht in Maryland for their perseverance in troubleshooting!

Corey

Thanks Corey for that update. Willie's Tug seems to have the same issue, it will not hold a heading off auto pilot without continuously turning the helm to port. As you said putting it on autopilot works just fine...as the autopilot does not mind continuing to make corrections.