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New shroud u-bolts

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Zoom 495 View Drop Down
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Post Options Post Options   Quote Zoom 495 Quote  Post ReplyReply Direct Link To This Post Topic: New shroud u-bolts
    Posted: 06 Mar 2015 at 1:44am
I am about to install a new set of shroud u-bolts that I have  received from JR. I am also looking forward to tuning the rig and getting a furler and a new headsail too!
The new upper shroud u-bolts have much longer legs than the old ones and will require drilling a new hole in the transverse knee for the bar to go through. Has anyone done this procedure and want to contribute any helpful tips for this project? Should I fill the old void?
I was hoping to do it whilst keeping the mast up. Has anyone done this before?
How much mast rake is desirable on the Contessa 32?
Thank you in advance and happy sailing,kris
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waratah912 View Drop Down
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Post Options Post Options   Quote waratah912 Quote  Post ReplyReply Direct Link To This Post Posted: 07 Mar 2015 at 4:11pm
It's not a difficult job, I changed mine while the boat was afloat on it's mooring. 
The webs, in my case anyway, were very hard, so buy a new high quality hole cutter.
Doing it with the mast up may make the job easier as the cap shroud tension will pull the old bolts out as you release the nuts, provided you slacken them off equally. 
Info about mast rake and set up is in the technical papers section of the website, see paper by Ian Brown.
Paul Smith
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Post Options Post Options   Quote Zoom 495 Quote  Post ReplyReply Direct Link To This Post Posted: 07 Mar 2015 at 7:00pm
Thanks Paul. I will be buying a new high quality hole saw.
Did you mend the old bar hole or did you see that as unnecessary?
The new u-bolts are of a larger diameter. Was it just a matter of increasing the size of the hole through the deck or was there more to it than that?
Thanks again,kris
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waratah912 View Drop Down
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Post Options Post Options   Quote waratah912 Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2015 at 8:15am
Kris, yes, they were a larger diameter, but on the same centers, so just drilled out the existing holes to accommodate.
I didn't fill the old holes.
Paul Smith
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Richard Ritchie View Drop Down
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Post Options Post Options   Quote Richard Ritchie Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2015 at 9:32pm

Every boat seems to be a bit different, especially if previous repairs have been made.  So here is our personal experience.  Sorry ti is a long post...

Doing the u-bolts in the water with the mast up was no problem.  If you are worried just lead a halyard to each side.  The mast won’t fall over!  But do loosen (and tighten) both sides equally or you will bend the mast.

Removing the old u-bolts was very hard, especially the lowers.  They were very stuck with sikaflex or similar in the threads and under the pads .    There was no room to get a big hammer to them upwards, (a passing shipwright tried and failed!) and where you could, the bolt bent… 

SO: the solution in our case was to take an angle grinder and cut the u-bolts off from above, flush with the deck, using the surface plate as a guide and to protect the deck.   Once the welds to surface plate were cut the bolts could be drifted out DOWNWARDS and the surface plate then prised free.  An advantage of this was that the metal plate (now with hole) provides a guide.  Another is that heat of grinding softened the sealant.   But do not cook the deck!  

 

The new u-bolts have a wider spacing (this will depend when your boat was made: mine is 1974).   You need to fill (one of) the old holes with resin/filler or you will not be able to drill the new hole accurately. Also needed to ream out the old ones.

 

Do think through what under-deck pads you will put for the u-bolts of the lowers: this spreads the load.    I think we had 15mm thick GRP plates from Jeremy about 5 inches long, plus large washers.  

 

Cutting  a new horizontal hole in the web for the uppers was not difficult, though the drilling was hard.  Make sure the bar is a snug fit.   Note that the web has a ply core, so drill in from both sides once the pilot shows you where.  We sealed edges of old hole but did not fill it.  Also make sure the new washers and flats are facing the nut.

 

Set in the new bolts at deck on sikaflex or similar bedding, lightly tightened.  Then wait 24 hrs for bedding to set before trimming off and tightening down to a seal.

 

Regarding mast set-up:  the rigger’s advice to me was 1.5 degrees of rake.   That is masthead about 6 inches back when measured from the deck.  There should be very little mast bend: 20mm backstay un-tensioned, 40mm tensioned Max.  Any bend MUST be backwards not forwards.

Hope this helps: interpret as relevant to your particular boat!

Richard Ritchie
Badger of Baltimore
IRL 120
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Post Options Post Options   Quote moongirl Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2015 at 9:39pm
I undertook the same task on Polar Star some time ago. Very easy to do without worrying about the mast falling down - provided its not blowing a gale! I used the 'core' from the hole saw to fill the redundant hole using West Epoxy resin + glass bubble filler - may not be necessary structurally but looks better.
I did have a look at another CO32 a couple of weeks ago & was astonished to see that there was no knee & that the cap shroud 'U' bolts simply passed through a beefed up deck with flattened bar simply bearing on the underside of the deck - surely this arrangement is not right as it would put a direct tensional pull on the deck rather than a combination of shear & tension provided by a knee - anyone else seen this? The Class Measurer confirmed to me that he had only ever seen the knee arrangement.

COLIN
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Post Options Post Options   Quote Galatea Quote  Post ReplyReply Direct Link To This Post Posted: 18 Mar 2015 at 1:02am
If you decide to replace the U-bolts on the hard, without the mast standing, it can be very hard to pull them out.  I ended up using a hydraulic car jack, supported on two pieces of wood and straddling the U-bolt, with a loop of webbing passing through the U-bolt and over the lifting plate of the jack.  Pumping the jack pulled out the U-bolts smoothly as if they were set in butter.
Mark
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