Removing rudder

PabloPicasso

PabloPicasso

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My mates GRP 30ft sailing boat needs a rudder rebuild. But there is no room to drop the rudder, and digging a hole is not an option. Could we tip the boat forward on its keel, slowly, bit by bit with a hydraulic car jack, adjusting the cradle as we go?

Is this a mad plan? Or just plain dumb to attempt?
 
hmmmm Pivoting the boat forward would place strains and stresses where they are not designed to exist.

If the boat is on a cradle, perhaps best to jack it vertically upwards, building a sub-frame as you go. 30 ft > 3 - 4 tonnes ? Could be done with scaffolding.


We have seen pics of forumites' boats where this has been carried out.
 
No crane

PhillM said:
Crane, hold in the slings, remove the rudder then put the boat back in the cradle.
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Yes. If We had known before the club lifted the boats this is exactly what we'd have done. But paying a mobile crane just for that lift would be way too expensive, and there are many other boats in the way now to.

It's cheap, safe , alternatives that are needed.
 
Depends on the cradle , but if its a substantial frame, how about lifting the whole lot, cradle and boat up alternating between front and back. Wouldent advise tipping the bow down to raise the stern, thinks could easily get out of control.
 
Eyore said:
Depends on the cradle , but if its a substantial frame, how about lifting the whole lot, cradle and boat up alternating between front and back. Wouldent advise tipping the bow down to raise the stern, thinks could easily get out of control.
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That's the way to do it. Borrow some medium density concrete blocks, they will still be usable when you are finished, jack up one end at a time not more than two blocks in each lift. To get started you may need a strong lever and a low profile trolley jack if there is very limited clearance and you are on concrete or if that is not possible a strong bar bolted across the legs at the lightest end to get started. I lifted the 6.5m. RSJ that carries my garage upper floor 2.5m. single handed this way but instead of using jacks I built the two temporary columns close to the centre of gravity so that I could rock it from one to the other. Because of the height and to allow it to be rotated upwards I made my columns 450mm. x 450 mm. but with a square cradle and a lift of about 1/2m. stability should be fine.
 
I would change the concrete blocks for wooden ones - the conkers have been known to crumble otherwise yes that's the way to go.

OP how high do you need to lift it ?
 
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PabloPicasso said:
Yes. If We had known before the club lifted the boats this is exactly what we'd have done. But paying a mobile crane just for that lift would be way too expensive, and there are many other boats in the way now to.

It's cheap, safe , alternatives that are needed.
Click to expand...

How long do you need to have the rudder off for, could you do all the prep then sort the rudder at lift in time in the spring?
 
PabloPicasso said:
My mates GRP 30ft sailing boat needs a rudder rebuild. But there is no room to drop the rudder, and digging a hole is not an option. Could we tip the boat forward on its keel, slowly, bit by bit with a hydraulic car jack, adjusting the cradle as we go?
Click to expand...

From pictures I have seen, the metalwork often doesn't seem to go far down the rudder. Halfway seems fairly typical. If it's a fll rbuild it might make things easier to cut the GRP off first and then remove the stock, replacing the complete new rudder at launch time.
 
JumbleDuck said:
From pictures I have seen, the metalwork often doesn't seem to go far down the rudder. Halfway seems fairly typical. If it's a fll rbuild it might make things easier to cut the GRP off first and then remove the stock, replacing the complete new rudder at launch time.
Click to expand...

Yes that does seem to be the easiest option. But I was rather hoping not to need to split the rudder completely. Perhaps cut a window in the side and check the issues and fix that way. But easier at home than in situ. Once we have taken a grinder to it we are fully committed with no way back! Getting the rudder off in one piece would be preferable. We may have to bite the bullet and go with the grinder.
 
PabloPicasso said:
Yes that does seem to be the easiest option. But I was rather hoping not to need to split the rudder completely. Perhaps cut a window in the side and check the issues and fix that way. But easier at home than in situ. Once we have taken a grinder to it we are fully committed with no way back! Getting the rudder off in one piece would be preferable. We may have to bite the bullet and go with the grinder.
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Rudder tangs are generally glassed in on one side of the rudder only so if you are going to cut a window, make sure you cut the side that the tangs aren't fitted to. Keep the cut part and use it to refill the gap. I repaired my tangs that way. I've posted this link before but have a look here - scroll down a little bit. http://www.randpsystems.co.uk/seawolf/rudders.htm
 
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