Should I cut my skeg? I've tried everything else...

[penfold]

You've not got it nearly hot enough; there's still paint on it, a lot more heat input required, probably a roofer's torch with a big bottle of LPG needed. Get it up to 200-250 degrees C and it will shift. The rudder stock is a concern, can you take some pictures so we can see what's what?

 

[demonboy]

It can only have been assembled one way and, as you already understand, reversing that process is now impossible.

Seems to me you have to either destroy the skeg (easy and easy to rebuild in the manner you suggested with a bronze plate through-bolted) or destroy the casting bit by bit (difficult to do and then difficult to fabricate).
You have clearly tried and thought about it every which way. Time to get the saw out and chop the glass skeg off and you will hopefully have the rudder off very shortly afterwards. You end up with a casting you can clean up inside and bush the bearing. You already have a workable solution to the cut off skeg.

One question that comes to mind: apart from the bolts in the new plate/upper skeg and the bolts in the new lower skeg/casting, how are you going to stick it all together so this can be disassembled next time. The next time won't just be cutting through glass but also through the new bronze plate. By what method, other than bolts, is the casting to be attached and secured to the repaired skeg? Seems like you have to leave it simply bolted through but perhaps secured by encapsulating it in glass for later peeling off? or straps ?

I think you've pretty much nailed it. Since this is a ten year procedure, glassing over the bolts isn't so much of a big deal. This time the trick will be to NOT epoxy glue the bronze casting onto the skeg and rely on the bolts alone. I didn't consider straps though. Do you mean vertical straps connecting the bolts on the casting with the bolts on the newly inserted plate inside the skeg?

 

[demonboy]

You've not got it nearly hot enough; there's still paint on it, a lot more heat input required, probably a roofer's torch with a big bottle of LPG needed. Get it up to 200-250 degrees C and it will shift. The rudder stock is a concern, can you take some pictures so we can see what's what?

My concern is going too hot. We could damage the bronze or even ignite the glass inside. Any thoughts?

Here's the stock, showing the top on the deck, where it comes through the deck inside the lazarette, and the bulk of the stock before exiting below.

 

[penfold]

There appears to be nothing holding it up there, so it's all the bottom bearing piece. Annealing temperatures for bronze start at over 400C, there's no danger of softening the casting inadvertently. The temperature and a naked flame present a significant fire risk and will damage the laminate, but as the alternative is going to totally destroy the laminate stub anyway that seems moot; have at least one person standing by with a hosepipe or buckets of water and a fire extinguisher.

 

[rogerthebodger]

I agree with penfold you need to heat the bronze casting to melt any epoxy /sealant inside the casting to release the castings from the keg GRP,

The gap sat the top need some leavers /wedges is forced in so that as soon as the epoxy starts to melt the casting is forcen off

 

[MapisM]

We built a 10mm plate that slides into the gap between the skeg and the casting and whacked it with a hammer.

I guess there was only so much downward force you could apply, in that manner.
I would try moving the casting UPWARD instead, hitting it strongly on its bottom with a big hammer.
In fact, you don't need a big movement to crack the epoxy that is holding the casting in place, if you are positive that it's the only reason why it doesn't move. Even less than one millimiter upward movement would be enough to crack the epoxy and set the casting free.

 

[simonfraser]

drill a hole through the rudder skeg and pull upwards to keep tension on it whilst you heat the lower bronze part ?

 

[Poecheng]

I think you've pretty much nailed it. Since this is a ten year procedure, glassing over the bolts isn't so much of a big deal. This time the trick will be to NOT epoxy glue the bronze casting onto the skeg and rely on the bolts alone. I didn't consider straps though. Do you mean vertical straps connecting the bolts on the casting with the bolts on the newly inserted plate inside the skeg?

Re the straps, yes, that is what I was thinking on the basis that you want never to have to think (however mad) about a weakened skeg stub giving way or the casting departing from the skeg (because it isn't epoxied on).
However, looking again at your proposal I realise the new inserted bronze plate connects to both the remaining skeg and down through the new stub and the casting will be through-bolted to the bronze plate. So that already performs the same function I was thinking of and should give peace of mind.

 

[demonboy]

I guess there was only so much downward force you could apply, in that manner.
I would try moving the casting UPWARD instead, hitting it strongly on its bottom with a big hammer.
In fact, you don't need a big movement to crack the epoxy that is holding the casting in place, if you are positive that it's the only reason why it doesn't move. Even less than one millimiter upward movement would be enough to crack the epoxy and set the casting free.

Yes, I was thinking of using a hydraulic jack to push the casting upwards but will try the hammer first.

 

[demonboy]

Re the straps, yes, that is what I was thinking on the basis that you want never to have to think (however mad) about a weakened skeg stub giving way or the casting departing from the skeg (because it isn't epoxied on).
However, looking again at your proposal I realise the new inserted bronze plate connects to both the remaining skeg and down through the new stub and the casting will be through-bolted to the bronze plate. So that already performs the same function I was thinking of and should give peace of mind.

If we go this route then rather than routing from underneath, which would be tricky, another idea is to create a vertical slot in the skeg and dove-tail the bronze plate into position.

 

[rogerthebodger]

Yes, I was thinking of using a hydraulic jack to push the casting upwards but will try the hammer first.

I would use a jack to preload the bronze casting then shock it by hitting the casting on the side with a big hammer in the same way as shocking a prop off the tapered shaft

 

[MapisM]

Yes, I was thinking of using a hydraulic jack to push the casting upwards but will try the hammer first.

The hydraulic jack would be fine if you should actually extract the casting upwards, but obviously that's not what you want.
The upward force is only meant to crack the epoxy and set the casting free, and I think the shock load of big hammer strikes can work better for that.
Either that, or what rogerthebodger suggested, which is a bit more sophisticated way to aim for the same result.
I'd try just hitting the casting upward on the bottom first, also becase all you need for that is a big/heavy hammer.
Failing that, the upward preload followed by side hammer strikes is another attempt worth making.

 

[ean_p]

You might try and hire / buy a couple of these so you could maintain constant force on the casting while warming the epoxy even to a 'rubber' consistency. With constant force it should / might start to move.......
VEVOR VEVOR Hydraulic Flange Spreader 8T Manual Hydraulic Flange Separator Integral Split Type 30mm Flange Wedge 9mm/0.35in Tip Thickness Splitter for Commissioning and Dismantling | VEVOR UK

 

[Alex_Blackwood]

I may be misunderstanding you but I would think the lower bearing plate has to be removed and drop the whole rudder, I would clean and inspect this area.
View attachment 163633

Plus one for that. I won't comment on what or what not needs doing, would have to be on site for that. However There seems to be undue concentration on complicated methods, involving butchery and blacksmithery. That bottom bearing went in so it must come out. I would have a cup of tea, take a deep breath and concentrate on that. Everything hinges on it!

 

[Ammonite]

Could you potentially tap / seal the holes and use compressed air or a hydraulic pump to help break the seal?

 

[Tradewinds]

Having watched the video it all becomes clear. Whose bright idea was it to epoxy the thing in place? I think I've had to drop my rudder three times in the last 20 odd years (shaft removal).
It think the bottlejack / sledge hammer shock treatment / high heat is the way to go.

Good luck. Don't do it again.

 

[geem]

Having watched the video it all becomes clear. Whose bright idea was it to epoxy the thing in place? I think I've had to drop my rudder three times in the last 20 odd years (shaft removal).
It think the bottlejack / sledge hammer shock treatment / high heat is the way to go.

Good luck. Don't do it again.

I have this job to do next year. The rudder has never been off in 43 years. I feel like I need to check the bronze bearings. Bottom shoe is stainless steel with bronze bushings. I have drawings so I don't expect major issues

 

[penfold]

Do you have access to basic workshop materials like threaded rod, nuts and steel angle? You could make an extractor set like this, screw or bolt the flanges to the skeg and casting and wind them apart; along with heating it should get it off. The threaded rod could be welded to the upper flanges or just fixed with nuts.

 

[B27]

Have you tried asking Oysta how they put it together?

 

[billskip]

What seems strange to me is that trying to remove the lower skeg and the rudder as joined pieces, why not remove the bottom section of the rudder to allow the skeg removal as a single piece? How much resistance is the rudder shaft causing, maybe none, but to be sure eliminate it imho.