Hydraulic autopilot below deck: How does the tiller arm disengage?

[Sailmonkey]

From the video it appears that your tiller has sheared off whatever pin was driving the rudder post.

The tiller should clamp tightly to the rudder post, in a manner that would prevent movement like is being seen in the video.

My opinion is that you’ve got a tiller arm that is either loose or too large for the rudder post in the first place.

[DougR]

Sail monkey has it right..... The autopilot tiller arm is loose and sloppy on the rudder shaft. The key has sheared ( if there ever was a key), the clamp bolts are loose and the autopilot has very poor control of the rudder.

You need to pull the tiller arm off and see what the problem is before more damage occurs.

DougR

[Chuck Hawley]

Just to pile on a bit...

Most autopilot tiller arms attach with two methods: a pin that goes through the tiller arm and the rudder shaft, which very accurately holds the two in alignment, and a "clamp" built-in to the tiller arm which firmly squeezes the tiller arm to the rudder shaft so the little pin isn't taking all the load. The rotational force of the frequent autopilot corrections would wear out either the pin or the rudder shaft hole, and it would get sloppy or break.

The asymmetry that you describe sounds like wear, as others have described. When the AP is hardover, there's a spot where the tiller arm moves but not the rudder shaft. That is NOT GOOD. No good comes from having slop in rotational mechanisms.

Whether you have a recirculating ball drive or a linear hydraulic drive, both are able to be "clutched" so they provide very little resistance when you're steering. I agree with other respondents that you don't want to go to the trouble of a tiller-arm disconnect. The ONE instance that I can think of would be a long distance fully-crewed race where you want the least steering friction, but no AP is allowed. Otherwise, keep it connected.

Finally, and I know this will be a bummer, but your lazarette/steering gear area looks incredibly cluttered. I bet it's really hard to diagnose anything regarding steering or other maintenance items because you can't get back there. Boats are frequently terrible at allowing maintenance. Even when you have access, it's a PITA. But I would strongly recommend that you either hire someone, or do it yourself, and try to remove and inspect this area of your boat. Steering failures can lead to fatal accidents, and at the very least, they slow down passages and make everyone consider mutiny. I put off dropping my rudder recently, and it resulted in a $4,000 yard bill to replace my lower rudder bearing. I should have been dropping the rudder every few years to make sure everything was A-OK. That which is easy to inspect, gets inspected. That which is not, well, you know the rest.

Chuck

[deblen]

Some notes & pics that may help
http://www.cruisersforum.com/forums/...nt-140087.html


Len

[Mike Banks]

My system was all hydraulic. Simplest is best. When one switched on the autopilot, the helm was disengaged. That was the only trick one had to know--before resuming control, turn off the autopilot.

Having used both cables and hydraulic, it really is worth spending the extra money to go all hydraulic. I never saw my autopilot move more than a few degrees when under sail--and when not under sail why would one have it turned on anyway? Wide swings of the rudder only happen when under manual control. If you can not turn the rudder far enough--you need a longer ram, or a different ram fixing pivot position closer to the rudder stem.

[B Tegge]

Have Ray marine hydraulic auto pilot. Installed it myself. It uses a hydraulic bypass valve when not in use. Also using the hydraulic cylender as rudder stops viods any warranty. I had to install rudder stops to limit rudder travel 35deg. from center.

[zeseb]

Thanks all for your answers, it gave confidence that the tiller arm should always turn with the rudder stock.

So i removed the attachment of my tiller arm by unscrewing it and I noticed there was a wedge on the rudder stock. My tiller arm was turning freely in the beginning because the 2 screw linking the tiller arm to the rudder stick was not fully screwed. I couldnt see it because its accessibility is barely possible.

So i placed the tiller arm fully perpendicular to the rudder stock and tightened the bolts properly. Now its all good. Indeed the rudder can turn -45 to 45 ich. Dont know why i thought 70...

Here is a drawing of my setup with a cut view from above.

[Beausoleil]

Did you replace the "wedge" (it's known as a key - sits in a slot machined into the rudder post and the base of the tiller arm). It should be nice and square, with no wear on it. If it's worn, then when the bolts holding the tiller arm clamp loosen (oh - they will loosen, and at the most inopportune time), the movement will wear it down and you'll get sloppy movement, creating more wear, ...

I'm surprised you have a hydraulic pump fitted out on your autopilot. The previous owner must have gotten a good deal on it, since it requires lots of extra stuff to install which isn't provided by a cable-steering setup.

[zeseb]

Originally Posted by Beausoleil

Did you replace the "wedge" (it's known as a key - sits in a slot machined into the rudder post and the base of the tiller arm). It should be nice and square, with no wear on it. If it's worn, then when the bolts holding the tiller arm clamp loosen (oh - they will loosen, and at the most inopportune time), the movement will wear it down and you'll get sloppy movement, creating more wear, ...

I'm surprised you have a hydraulic pump fitted out on your autopilot. The previous owner must have gotten a good deal on it, since it requires lots of extra stuff to install which isn't provided by a cable-steering setup.

It got loose with the movement because the previous owner didn't put a second bolt so it got unscrewed at some point. The key is all good and it was in good nick. But you are right, those stuff breaks all the time at the wrong moment indeed.
The boat has an hydraulic ram. It's a 21 tons steel boat with a heavy rudder so it requires some torque. There is as well a wind vane. Lot of stuff.