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Current Replies for Main Upper Shrouds
 
  Main Upper Shrouds (dmartis)
Posted: 1:27:24 pm on 3/15/2013 Modified: Never
 
I'm in the process of replacing the main upper shrouds this year on my Mark III.  The existing shrouds are 1/4" cable and have a small copper sleeve on them that fits over the end of the spreaders.  I'm not sure what the purpose of such a sleeve would be - shouldn't the spreaders just be in compression, and not pick up any up/down loads from the shrouds?

Does anyone else have this sort of thing? Or should I just get rid of it on the next set?

Dan Martis
Dream Catcher
Oakville, Ontario
Mark 3, Hull #636
  Re: Main Upper Shrouds (carriden)
Posted: 4:55:15 pm on 3/15/2013 Modified: Never
 
Hey Dan,
This is standard on C&C rigging.  Carriden has it, my 25 had it too.  In essence, the copper swage is a marker to ensure the correct dihedral angle for the spreaders, so that they maintain the proper angle between the shroud and the mast.  You may have noticed that when the mast is up and the rig is tensioned, the spreaders do not sit at an exact right angle to the mast.  Rather, they are tilted slightly upwards, so that they bisect the angle formed by the stay as it inclines in towards the mast head.  The copper swages are usually partnered with small washers and they get positioned immediately below the spreaders, when you are rigging the mast prior to putting it up.

In short, yes you should replicate the copper swages, in exactly the position on the shroud where they currently sit.  When Bristol Marine replaced my one upper shroud, they made sure to include the swage.

Marcus from Carriden

Mk III, Hull #847
Oakville, Ontario

  Re: Main Upper Shrouds (dmartis)
Posted: 9:08:38 pm on 3/16/2013 Modified: Never
 
Thanks Marcus - I told James he should ask you about this!
  Re: Main Upper Shrouds (davidww1)
Posted: 10:21:42 am on 3/17/2013 Modified: Never
 
If it's not obvious from what Marcus has said, the copper swage and washer must</> be positioned below the spreader when the rig is up, or the spreader end will work its way downwards on the shroud. This will reduce tension on that side, which will exacerbate the effect. If left unchecked, this might lead to failure of the spreader at the inboard end and consequent rig failure.

If you see a C&C with the spreaders cocked down instead of up (anhedral rather than dihedral, in aviation terms) it is probably because the owner has mis-positioned the swages (or has replaced the shroud without replacing the swage).


David Weatherston
Towser, Toronto
C&C 27 Mk IV

  Re: Main Upper Shrouds (davidww1)
Posted: 10:22:12 am on 3/17/2013 Modified: Never
 
If it's not obvious from what Marcus has said, the copper swage and washer must be positioned below the spreader when the rig is up, or the spreader end will work its way downwards on the shroud. This will reduce tension on that side, which will exacerbate the effect. If left unchecked, this might lead to failure of the spreader at the inboard end and consequent rig failure.

If you see a C&C with the spreaders cocked down instead of up (anhedral rather than dihedral, in aviation terms) it is probably because the owner has mis-positioned the swages (or has replaced the shroud without replacing the swage).


David Weatherston
Towser, Toronto
C&C 27 Mk IV