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Old 02-13-2018, 10:48 AM   #1
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Mainship 34T rudder and auto-pilot

After lots of searching, I just purchased a "new to me" 2006 Mainship trawler. I took delivery of the boat on Florida's East coast and last week ran her for 6 days through the Keys and up to her home slip here near St Petersburg on the West coast.
For the most part the trip went well except that when traveling past the 10,000 islands we had 25-30kt winds and 4-5ft following seas. This required extreme manual input (almost lock-to-lock) to the steering to keep the boat on course and not broach.
During this time, the rudder thru-hull developed a leak that let in during this time a few gallons of water into the bilge. The leak seems to have subsided once the steering wasn't so wild. Since that episode, the auto-pilot also stopped working.

So as a trawler newbie, a few questions:
1) is the rudder leak normal under extreme lock-to-lock steering. If not, what is the best way to address? If I tighten it, it could exasperate my auto-pilot issue (next point)
2) can this cause the rudder packing to become stiffer to the point where the auto-pilot can no longer produce the required pressure to function?
3) Does anyone have advice on the best way to diagnose the autopilot issue.

Thanks in advance for those that can assist. :-)

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Old 02-13-2018, 10:56 AM   #2
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Can't help with the rudder leak or the autopilot failure, but I can comment on the autopilot steering in a following sea:

The 34T like others has a small rudder but the 34T also has a wide beam and transom. This means that a heavy following sea will push it around. I never experienced manual lock to lock steering in a following sea, maybe half turns back and forth. Autopilot steering was extreme and in those conditions it would make 30-45 degree S turns.

What dampened this out to about 10-15 degrees on autopilot was to add the gyro feature. On that particular Raymarine autopilot you could add a black box and it would provide gyro steering along with the standard fluxgate compass steering. Some of today's autopilots have them built in.

If you have to replace your autopilot's control head, get one with the gyro feature.

Oh and is your steering now tight manually. If it works freely manually I doubt if it is affecting your autopilot operation.


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Old 02-13-2018, 12:43 PM   #3
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As David notes, they can be challenging in following seas, though I never come close to needing full rudder.

What make and model of AP?

I had a Raymarine S2. Even the addition of the gyro didn't help it much. (I believe there was a problem with my particular unit.)
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Old 02-13-2018, 06:21 PM   #4
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Lock to lock? I can't imagine conditions that would require that amount of rudder in order to maintain a course. I think our OP will modify his language to better describe what he experienced.
A leak of the rudder gland is unrelated to the autopilot. If it has subsided, it may be that it had already put some water into the bilge, that had been trapped behind some barriers and slopped over in the motion of that passage, so had actually taken quite a long time to accumulate. In my experience, leaking packing never fixes itself, so you will still need to repack that gland.
The failure of the auto pilot seems to be related only to the violence of the passage, however, once failed, you will need to call the manufacturer or its rep to get advice on rehabilitating or replacing it.
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Old 02-14-2018, 07:59 AM   #5
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A rudder that gets stiff when swung from lock to lock may be bent.

Something to check on next haul out.

Folks are much more likely to R&R the packing for a shaft leak than the smaller water from a rudder leal.

See if the packing has been renewed in the past few decades , if you are going to repack, use some modern material, and most dripping hassles will go away.
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Old 02-14-2018, 07:47 PM   #6
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Disconnect the rudder linkage and turn it by hand, feeling for tight spots, then try and shake it in various positions to test for wear in the bushings.
Try and tighten the packing gland, or not a huge job to just replace the packing.
While it’s disconnected, test also your steering system, and check it’s fluid level.
The autopilot manual should have a troubleshooting guide, but a good starting place is to verify that the pump runs. Fuse???
You can lead a horse to water,
But you can't make him ski...
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Old 02-14-2018, 08:21 PM   #7
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To your questions:
#1 No. Repack it properly. The movement of the rudder shaft is dead slow so there should be little to no water leaking.

#2 Shouldn't unless as F.F. points out the rudder shaft is bent or damaged. Not likely unless a grounding has happened. A/P like yours usually are hydraulic and can produce quite a bit of power to move that rudder unless the A/P is undersized.

#3 Go through the manual and spend some time studying it. There are several things I can think of; rudder position sensor failed or out of place; blown fuse or circuit breaker tripped; wiring problem. If no manual then get one. Once you have checked the manual and the suggested troubleshooting steps, hopefully there is such, then ask more questions.
From your description there is not enough info here to start except toss out a bunch of wild ideas. You will get advice.

Different boat but I've learned to slow down in stuff like that. Unless you can plane in those conditions then your speed needs to be substantially less than that of the waves so they roll under you. If the wave and boat speed are too close then the boat will be slewed around a lot worse than need be, maybe pushing the boat bow into the backside of the wave ahead as the hull charges down the wave face you are on. That can cause a slew and maybe a broach.

Use the engine. If the boat is not correcting as you need then give the engine a sharp shot of throttle. That will send a burst of water past the rudder which will improve rudder control. You are not trying to speed the boat up, just trying to get that shot of water flowing past the rudder to get back some control.

Agree that you need to repack the stuffing box. Use Gortex GFO or Duramax and the box should remain dry for years with minor adjustments from time to time.

Get the A/P turn rate checked. Mine is a different A/P but if the turn rate is too high the A/P motor may be overloaded which will do it or the controller harm. THis may be an actual adjustment to the hydraulic pump, not the controller. Again yours is different from mine but hydraulics are hydraulics and have similarities from mfgr. to mfgr.
Overload means the motor cannot get up to proper working speed so lugs and draws heavy current resulting in sluggish response. The proper rate adjustment will allow the motor to wind up fast producing a faster rudder response without overloading. This may not be your case but find out.

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