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Old 21-12-2021, 13:05   #61
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Re: Bent rudder shaft?

Originally Posted by TrentePieds View Post
It appears from your photos that the stock is bent immediately above - or just at - the upper bearing where it exits into the steering flat. How could that possibly have happened?

As JimBunyard said the boat has a full skeg, as your attached drawing shows. Stan Huntingford's designs were sound, and he would have designed the rudder arrangements well, and simple enough that Cooper Yachts could build them easily. That your rudder turns, even if it feels "resistive", would indicate that from the upper bearing right down to the gudgeon at the bottom of the skeg, things are alright. However, the friction that makes the steering "resistive" will be found where the stock goes through the upper bearing.

So it looks to me as if you are faced with a sorrowful situation:

The top bearing should be replaced, and a new straight stock should be provided. That cannot be done without withdrawing the entire rudder, c/w stock, FROM THE BOTTOM! That will require hauling to gain access to the gudgeon fastenings.

The bent part of the stock will not, obviously, go through the steering well and its bearings as it is. The stock must therefore be cut just above the upper bearing. The collar should come off to do this. Even when so cut it is likely that the cut end of the stock will damage the bearing at the bottom of the hull as you withdraw it.

Cutting with a torch would be extremely dicey working within the steering flat so a saw is preferable, but, as I'm sure you know, sawing through stainless steel - which is what the stock will be - has its own problems!

Even when the rudder and stock are out of the boat it is unlikely that welding a new piece of stock to the part still in the rudder blade will be possible because proper axial alignment will be a problem. It would be, if it is possible at all, a job for skilled professionals.

You ask specifically for a cause. This damage has originated from WITHIN the steering flat, I'm pretty sure. It has nothing to do with hitting a reef or any other such thing.

You ask specifically for a cost estimate. IMO - without doing actual costing - I would suggest something in the region for $40,000. If you do not already own this boat I would suggest you find another candidate for your ownership.

All the best to you.

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Old 21-12-2021, 13:15   #62
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Re: Bent rudder shaft?

agree with this opinion,
such a strong rudder post would take immense force to bend it, a pilot's hydraulic cylinder could not.
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Old 21-12-2021, 13:31   #63
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Re: Bent rudder shaft?

Originally Posted by bunnins3 View Post
Hi all,

I am needing a solution for the best way to repair a bend rudder shaft. It appears that the top of the rudder shaft is bent about 15 degrees and steering feels resistive. Unknown cause - potentially from previous owner hitting a reef?

The boat is a full skeg. What is the best way to fix this? Has anyone had similar issues? And prices to fix? I am worried the rudder shaft will not be able to be removed without having the cut it.

Thank you for any help,

On second thought the shaft might have cracked and has nearly broken off. Stainless can crystallise and get brittle over the years, besides it would have bend above the rudder tube, not inside.
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Old 21-12-2021, 13:44   #64
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Re: Bent rudder shaft?

When I first saw the photo of the top of the rudder post, it reminded me of the top of the rudder post on my Fantasia35. I have a solid ss, squared-socket ended rudder post extension - at least 7í long - that attaches to the squared-top of the rudder post. This extends the rudder post all the way through the top of the aft cabin that then has a tiller attached to act as an emergency rudder.

If such a rudder post extension is found on the boat and if an inspection of said rudder post extension shows signs of it having been used as an anchor point (like markings that a chain would leave), then you could logically assume that the rudder post extension was used as an anchor point. A check of the port in the deck through which a rudder post extension would fit might 1) show signs of having been stressed on the same side as the bend in the rudder post and 2) provide a way to straighten the rudder post outside of the below deck area. If all of the above is true, you may be able to reverse the process that bent the rudder post in the first place to straighten the bent rudder post using the rudder post extension to apply the needed pressure. Just sayiní.
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Old 22-12-2021, 07:00   #65
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Post Re: Bent rudder shaft?

Attach the emergency tiller if you can to assess the impact of the bend so that you can see and feel how it has impacted function. Next may be cutting off the top of the shaft to drop out the rudder, do this by hand to avoid work hardening the stainless steel cutting a couple inches above the seal. Slow is best to avoid heat. You will have to rebuild the top section of your rudder post and likely cut away a few inches of the top of the rudder to expose post that is straight. If you stay with what you've got, that is your rudder is not already on its way to blowing up, you would then purchase a short length of shaft having the same diameter and pay a shop to mill a full width slot in the newly exposed shaft and a fitted tab on the new section. The slot and tab depth and length should be at least equal to the shaft diameter and roughly 25% of the dia wide. The top section of the post must be machined to fit your e-tiller before this section is welded using pre-fabricated sleeve to insure proper axial alignment as the fab is completed. Finally, build back and contour the top of the rudder using glass and epoxy, apply three to five coats of barrier coat before your anti-fouling paint. You will end up with a repair having a density nearly the same as before. Fix probably about 3K, but 2-3x that if you can't do the removal and re-install yourself. If your boat requires a new rudder assy I believe todays designers target neutral or slightly positive buoyancy.
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Old 22-12-2021, 07:20   #66
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Re: Bent rudder shaft?

Mate just a thought.
It seems that this could be a conversion from tiller to wheel steering, in which case the bend may have been purposefully done to accommodate the tiller.
The top of the shaft looks like it had some fitting attached.
I'm not an engineer but just looking outside the square.
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Old 06-01-2022, 18:37   #67
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Re: Bent rudder shaft?

Hi all, thank you very much for all your information.
We decided not to purchase the Cooper 416 due to too much damage and costly repairs.

We are now considering a Corbin 39 but has some compression dents on the hull, if anyone could help, please look at my new thread.

Thank you!
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bent, issue, reef, repair, rudder, Shaft, skeg

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