Bent rudder shaft?

[Dieseldude]

Originally Posted by col50

Yes I am sure about that. Removal of the rudder on this boat is done by removing the bearing (support) at the bottom of the skeg. Look at the drawings on page one of this discussion and it will make sense.

The stock is stainless steel, and I'll presume that the rudder is fiberglass. One would have expected them to be separable. I could not see enough detail on the drawing to know this. But I'll take your word on that. So no lathe operations on the stock are possible according to them being one integrated piece. This could also rule out straightening in a hydraulic press. It would be quite an awkward piece to set in a press.

[Pauls]

The stock was bent from some force inside the boat. That is obvious.

If a force inside the boat could bend the shaft, then an opposite force inside the boat can bend it back.

Work out a way to support a hydraulic ram inside the hull. The ram cylinder should bear against the top of the rudder shaft, to maximize leverage. If you give us the rudder shaft diameter and the distance from the top of the shaft to the upper shaft bearing either Nord Sal or I can calculate the force the ram must apply to bend the shaft straight. I believe you will find that the load required will be practical to achieve.

Straightness of the shaft is determined by moving the rudder and measuring the shaft movment during rotation. You don't need perfection here, but you should get it close.

The hydraulic cylinder support must bear on strong points and must spread out the load enough to not damage the hull. I've done this on several occasions, using 4x4s. You will probably need to spread out the load where the 4x4s bear against the hull by supporting them with rigid supports that bear against hull structure and distribute the load.

After straightening the shaft I'd drop the rudder and inspect it carefully. It's likely that there will be some fiberglass cracking where the shaft exits. This should be sealed.

[captain38]

I agree with Jimbunyard. That bend inside the boat could not be the result of grounding. Nor could any force from within have bent the shaft without causing other damage.
I expect the shaft will be found heavily corroded in the tube or bearing - looking like swiss cheese from stagnant seawater causing crevice corrosion which occurs from de-oxygenated salt water. Sorry, this likely will require shaft replacement.

[Sail Away 3]

I agree with much of what has been posted. The pictures help clarify much of this discussion. Many possible causes that would require careful consideration. Especially to prevent in the future. But moving on... remove the steering arm from the shaft and the upper keeper that prevents the rudder from falling out if the lower support, shoe, gudgeon is lost. Attempt to inspect down into the fiberglass tube for damage and extent of the bend. If all appears decent, attempt to straighten the shaft enough to remove the rudder straight down. Plenty of great suggestions on here on ways to do that. If that cannot be done then cut off all the shaft above the glassed tube. Angle grinder and cut off wheel works great, control the sparks. Remove lower support and drop the rudder out. If it is still intact and you have the equipment and skills to straighten it then great and it will be back in the boat in no time. Otherwise take it to a metal workshop and have it done. Lauderdale propeller straighten mine one year.
If you had to cut the shaft I can explain how I rebuilt the rudder on my Kirby 30 race boat...
A job done right will save you heart aches 💔 down the road... and yes Virginia cruising is learning to do repairs in exotic locations.

[Dieseldude]

Originally Posted by Pauls

The stock was bent from some force inside the boat. That is obvious.

If a force inside the boat could bend the shaft, then an opposite force inside the boat can bend it back.

Work out a way to support a hydraulic ram inside the hull. The ram cylinder should bear against the top of the rudder shaft, to maximize leverage. If you give us the rudder shaft diameter and the distance from the top of the shaft to the upper shaft bearing either Nord Sal or I can calculate the force the ram must apply to bend the shaft straight. I believe you will find that the load required will be practical to achieve.

Straightness of the shaft is determined by moving the rudder and measuring the shaft movment during rotation. You don't need perfection here, but you should get it close.

The hydraulic cylinder support must bear on strong points and must spread out the load enough to not damage the hull. I've done this on several occasions, using 4x4s. You will probably need to spread out the load where the 4x4s bear against the hull by supporting them with rigid supports that bear against hull structure and distribute the load.

After straightening the shaft I'd drop the rudder and inspect it carefully. It's likely that there will be some fiberglass cracking where the shaft exits. This should be sealed.

I like that idea of using the machinery to straighten itself, if things can be supported and stabilized sufficiently. There is some danger of the set up flying apart under stress, so an extremely rigid arrangement would be needed. And care must be taken not to over stress the hull. The bearings may suffer, but presumably , they can be replaced easily. If you want to be fussy, once straightened visually close, a dial indicator can be set up and stock rotated to check for run out until you get it very close. But of course it need not be perfect. How close it need be requires some experience to determine. But if it kinda works in its present state, getting it even within 1/16 to 1/8 inch run out would be a vast improvement. Considering the work involved, it would be good to get it close in case you are not happy with crude results later.



One poster speculated that the stock could be corroded due to stagnant water in the tube. So straightening might only end up being for the purpose of removal if badly corroded. But who knows, you may find that it is quite serviceable. If it has some scattered pitting, it may still be ok. I have heard of pits in a prop shaft being ground smooth and polished to prevent further corrosion. You end up with some smooth dimples, but if not large and numerous, it can retain sufficient strength. So this might be an option if you find moderate pitting.

[MEC]

the rudder shaft is bent above the upper shaft bushing because the shaft is not supported by a bearing/bushing above the quadrant. The hydraulic forces applied to the cantilevered rudder shaft bent the shaft.


If the shaft is replaced by manufacturing a new rudder, the shaft will bend again due to the unsupported shaft.


The rudder system needs to be redesigned by adding a shaft guide bearing located above the steering quadrant.


Also provision should be made to connect an emergency tiller to the shaft in case of failure to a steering system.


PS a solid shaft may not be the strongest/stiffest structural member. Rudder shafts are usually large diameter thick wall tubes.


I hope this information is useful

[David Mathis]

This is a new problem. Rather than guess, the recommendation is to have someone with experience in this area take a look. My advice would only be another guess.

[Dieseldude]

Originally Posted by Martinini

Find another rudder. Cut the old one at or below the bent part with sawsall. You will have to raise the boat high enough to drop the existing rudder or do what I did and dig a hole under it and drop it into the hole to pull. Save all the parts in case you have to have a fiberglass shop fabricate a new rudder. If you can work with fiberglass you could do it yourself. It's not as hard as you think. But you need the old one for reference. Will need to cut in two to see the internal structure to replicate. Again sounds hard but not really.

If you have to go the drastic route of cutting the stock from the rudder, the stock may be salvageable. I would make index marks on each side of the cut with a center punch, or better yet scribe a line that will extend each side of the cut. After cutting away the rudder, perhaps a machine shop can stick the stock together. I have seen thjs done to machinery shafts.


The work is done on a lathe. Each piece is faced to smooth off the saw cut, bored to accept a dowel, and chamfered to make a notch for layers of weld. The pieces are fitted together using the dowel to hold them in alignment for welding, and aligned radially using the index marks made earlier. The welded area is turned smooth. Then you have your stock back in one piece, ready for fabricating a new rudder over. Of course you have the task of straightening the stock which has already been discussed. Have to be mindful of welding stainless to avoid chromium depletion that would cause corrosion. The particular stainless alloy should be found out from the manufacturer. The right alloy welding electrodes must be selected. No point in doing a repair that will corrode. Welding must be done slowly to prevent overheating and thermal stress that would weaken and cause bending. The stock need not end up perfectly straight though. This would be a job for a machine shop experienced at marine stainless fab and repair. Should be lower cost than a new stock.

[DeValency]

Originally Posted by Pauls

The stock was bent from some force inside the boat. That is obvious.

If a force inside the boat could bend the shaft, then an opposite force inside the boat can bend it back.

Work out a way to support a hydraulic ram inside the hull. The ram cylinder should bear against the top of the rudder shaft, to maximize leverage. If you give us the rudder shaft diameter and the distance from the top of the shaft to the upper shaft bearing either Nord Sal or I can calculate the force the ram must apply to bend the shaft straight. I believe you will find that the load required will be practical to achieve.

Straightness of the shaft is determined by moving the rudder and measuring the shaft movment during rotation. You don't need perfection here, but you should get it close.

The hydraulic cylinder support must bear on strong points and must spread out the load enough to not damage the hull. I've done this on several occasions, using 4x4s. You will probably need to spread out the load where the 4x4s bear against the hull by supporting them with rigid supports that bear against hull structure and distribute the load.

After straightening the shaft I'd drop the rudder and inspect it carefully. It's likely that there will be some fiberglass cracking where the shaft exits. This should be sealed.

Bravo, Paul! - I was wailing to read this smart analysis.

I didn’t see if the OP provided the shaft diameter. Somehow it looks to me like less than 2”…
Now, if it was bent like this inside, and the boat stayed afloat, and the shaft bearing sleeve has not been torn away from the hull/structure, the pressure bending it may have been much lower than we imagine. Yet, Hard to believe the hydraulic steering cylinder could generate such force - but if it could, maybe holding the rudder and operating the steering in the revers direction of the deformity could work?. I tend to think it may be from some unusual force on the emergency tiller shaft (that should be installed on top of the rudder shaft)

I would look into it straightening it inside after removal of the steering arm, using a portable hydraulic press or even with a large 1” screw - both will require a machine shop to build a heavy L shape jig with clamps over the shaft right above the bearing sleeve at the bottom and create a pressing point at the top of the shaft, in order not to generate any force on the bearing.

Depending on the location (is it Fiji?) and the machine shops available it can probably done in about 10-20 hours of a good well focused (without the common cheating) mechanic/welder. I’m sure most US boatyard will not do anything under $10-15K even if it will take them 20 hours - but that’s a different discussion.

[robertmfranklin]

I am troubled by the response of some posters who seem to gravitate to the more complex approach to this problem without suggesting a thorough investigation of more simple one.

Although, a few have. We started with a basic throw away the boat approach at $40,000. Now things seems to have settle down.

My understanding is you can buy a good used sailboat without any significant problems about the same money as an "expert" recommends for repair.

Its silly, but if you've ever had your car serviced at a dealership, you know what I am talking about.

It is what i refer to as the "badge" approach.

There seems to be a wealth of DIY talent on this site. But even then approach to problems vary widely. Rather than speculate about the source of the problem, I say get the thing dropped and figure it out then.

[Jim Cate]

Rather than speculate about the source of the problem, I say get the thing dropped and figure it out then.

YES! At this point nothing further can be determined without dropping the whole shebang out of the hull and having a good look. Hopefully the extraction won't be too encumbered by the bend! With the shoe at the bottom of the skeg removed I think there's a good chance you will be able to woggle it out... and then the fun begins!

Good luck, mate

Jim

[Celestialsailor]

Hate to rain on your party but I'm not thinking it will drop out the rudder tube with a bend like that in it. Just sayin...

[jimbunyard]

Doesn't look like the OP is coming back, though stranger things have happened.

I say then, yeah, let's cut to the chase, and see if we can twist it off with a big crescent wrench, as someone advised previously. If it breaks, you've found the problem and it's easier to remove. If not, then an attempt can be made to straighten it. If it straightens with difficulty, then the discussion must be had if it can be trusted for it's expected service, which can be guestimated after it's inspection upon removal.

According to the OP's first post, the only problem was 'stiffness' in it's operation, and taken assumptively, the discomfort at knowing the shaft was bent, and probably the uncertainlty that that introduced.

For me the 'simplest, most direct, first' approach holds the most attraction, whilst the 'weld and machine if needed' one seems furthest from the best realworld solution, unless there's an extenuating circumstance(s).

It'll be nice if the OP shows back up...

[Jim Cate]

Originally Posted by Celestialsailor

Hate to rain on your party but I'm not thinking it will drop out the rudder tube with a bend like that in it. Just sayin...

Yep, could be right, but alternatively, you could be wrong! Little to be lost by trying, and much will depend upon the clearances in teh upper bearing, or whether the upper bearing could be removed entirely or dragged out the bottom with the stock.

So, w hy not give it a go? If it won't come, push it back up and go to plan B.

Jim

[Icarus]

Originally Posted by bunnins3

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,

Thanks

Cut the bend shaft using an angle grinder, or hacksaw if you have the patience.
Remove the bottom bearing and remove the rudder.
Make a new rudder.