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Rudder stock problem


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I've just bought a 1997 Dehler 35 CWS that has been ashore for 5 years.  The steering was very stiff and as part of getting her ready for sea again I got the yard drop the rudder and I have planned to have new bearings made.

The top of the stainless steel stock, just where it enters the blade is looking very odd.  I'm not sure if this is some form of corrosion or has it been machined so the foam adheres better. 

All suggestions welcome.  I have sent the photos to the surveyor too.

 

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Yikes! Looks like a new rudder is in your future. That is the highest stress area. Nobody would machine it there. Shocking that this is on a comparatively new boat: 1997.

Is it a tube or solid? Even if solid, removing the outer diameter greatly (exponentially) reduces the strength.

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It is hard to imagine it was made that way on purpose. It also looks like the top of the blade is notched where the stock enters. Is there a reason for that such as a strange profile on the hull where it meets the rudder? Finally you have a gap where the stock enters the blade and some exposed foam in the same area. All this adds up to a need for invasive investigation. I wonder if all this is a sign of prior damage and repair.

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53 minutes ago, slug zitski said:

Severe corrosion 

you have an electrical leak 

that rudder is history 

 

Jefa makes many rudders and bearings for European production boats 

check their website 

https://jefa.com/ftp/old_boat_spare_parts/

 

Correct - you have severe corrosion right at the load point. I'm not certain on why, that looks like anoxic corrosion to me. I really wonder how far down into the blade it went.

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Sadly that rudder stock is dead. It has ceased to be! Its expired and gone to meet its maker.  Bereft of life its kicked the bucket,  shuffled off 'is mortal coil, run down the curtain and joined the bleedin' choir indivisible!!

Its dead Jim.

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2 hours ago, Zonker said:

Sadly that rudder stock is dead. It has ceased to be! Its expired and gone to meet its maker.  Bereft of life its kicked the bucket,  shuffled off 'is mortal coil, run down the curtain and joined the bleedin' choir indivisible!!

Its dead Jim.

it's not dead, it's just restin' a bit...

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2 hours ago, Zonker said:

Sadly that rudder stock is dead. It has ceased to be! Its expired and gone to meet its maker.  Bereft of life its kicked the bucket,  shuffled off 'is mortal coil, run down the curtain and joined the bleedin' choir indivisible!!

Its dead Jim.

It's piniin' for the fjords.

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I don't intend to cross oceans with the rudder is such poor shape, I need to patch it up to get the boat home.  She's a 6 hour drive away and I've paid for the marina till January.  Jefa are quoting a 3 month build time for a new one.  Tomorrow, I'm planning on opening up where the shaft enters the blade to see how extensive the corrosion is.  

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3 hours ago, Whinging Pom said:

I don't intend to cross oceans with the rudder is such poor shape, I need to patch it up to get the boat home.  She's a 6 hour drive away and I've paid for the marina till January.  Jefa are quoting a 3 month build time for a new one.  Tomorrow, I'm planning on opening up where the shaft enters the blade to see how extensive the corrosion is.  

3 months delivery time ..Sounds about right 

in summer most of those companies close down for holidays 

if the rudder functions you can certainly go sailing inshore 

be alert .. fair weather sailing only 

also inspect the rudder bearing 

new rudder and new bearing is the preferred refit 

 

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5 hours ago, Whinging Pom said:

I... Tomorrow, I'm planning on opening up where the shaft enters the blade to see how extensive the corrosion is.  

Why? What is the decision process? Better to see if a couple of yard workers can break the rudder off by hand without the boat coming off the jackstands.

Actually...eyeballing the size of that stock compared to the electrical tape it would appear to be a very small solid shaft. If so, it was minimal when new. Going sailing with that is irresponsible without some kind of backup plan for when it fails.

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17 minutes ago, Borracho said:

Going sailing with that is irresponsible without some kind of backup plan for when it fails.

wot he said .

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I cut a sliver out of the blade to see what's what.  The shaft apart from what the surveyor reckons is crevice corrosion is perfect. A couple of mm out of a shaft thickness of 60mm has been lost.  New bottom bearing has been ordered and we'll limp home with the existing rudder and get a new one made over the winter.  The rudder tube is massive and extends well above the waterline.   I'd put a photo up but the software isn't co-operating.

 

 

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2 hours ago, Whinging Pom said:

….A couple of mm out of a shaft thickness of 60mm has been lost.  ..

The sweet thing about crevice corrosion is that the cracking is always so much deeper than what is seen on the surface.

Plus, a couple of mm groove in a 60 mm shaft reduces the second moment, and therefore the structural performance, by 25%. 
 

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3 hours ago, Whinging Pom said:

I cut a sliver out of the blade to see what's what.  The shaft apart from what the surveyor reckons is crevice corrosion is perfect. A couple of mm out of a shaft thickness of 60mm has been lost.  New bottom bearing has been ordered and we'll limp home with the existing rudder and get a new one made over the winter.  The rudder tube is massive and extends well above the waterline.   I'd put a photo up but the software isn't co-operating.

 

 

The shaft is solid, not a tube? That's a bit different. If it is a tube, it's 2mm out of whatever the wall thickness is. And crevice corrosion always goes much deeper than it appears to.

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