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1 . 
  S&S Swan Maintenance - Swan 36 mast tuning
 
 
 
26 June 2010 - 09:14
#1
 
  abardy Join Date: 13 June 2010
Posts: 11
 
  Swan 36 mast tuning  
  Dear fellow enthousiasts and the Professor,

I rigged my S&S for the first time last week and would like to have information about tuning the mast. My previous experience is from fractional rigs and I have understood that mastheads are simpler to tune, but would still like to receive exact information on the order, procedure and things to check while tuning.

The mast I have is not original, but for what I know it is exactly like the originals in terms of size, shrouds etc. The boom is different though.

Best regards

Aleksi
 
     
 
 
26 June 2010 - 13:21
#2
 
  Matteosalamon Join Date: 29 January 2007
Posts: 481
 
 
Dear Aleski,

a very interesting, simple and illustrated book on this matter has been written by Ivar Dedekam

Fair Winds!

Matteo (38/067 Only You)
 
     
 
 
26 June 2010 - 21:11
#3
 
  the professor Join Date: 02 January 2008
Posts: 873
 
 

Dear Aleksi


Taking the risk of sticking out my neck - here some basic information,


The recommended book may contain more.


1. Mast rake


Originally the recommendation was 6", but it could be noted that for later S&S models rake was increased to abt 1 degree, and this would suggest 9" instead.


This assumes rig length is standard


2. Shroud pre-tension


Shrouds should stay tight on the leeward side up to normal heeling angles on the wind. Rigging screws should not be tightened hard at the dock, this is bad practice particularly for stainless screws, because threads of this material easily gall. Pre-tension at the dock is also guesswork, this should be done under sail.


Would be interested to hear what the book suggests before continuing on this subject.


3. Backstay tension on the wind


If there is a hydraulic backstay tensioner with pressure gauge the make and size is required in order to work out the proper pressure. In addition the rig length, and the diameter of the head- and backstay is needed, and whether they are wire or rod.


Kind regards


Lars

 
     
 
 
26 June 2010 - 23:01
#4
 
  abardy Join Date: 13 June 2010
Posts: 11
 
 
Thank you,

I ordered the book from Amazon. Feels like an interesting read in many respects.

 
     
 
 
04 October 2010 - 19:03
#5
 
  ludovic Join Date: 25 July 2008
Posts: 22
 
 
Thank you for this Thread, I will also buy the book.

Here is my problem:

We did a mast and rigging refit last winter on our Swan 47 (hull 59). We replaced all standing rigging (mix of original rod and cables) with compacted cables that have higher resistance to extension than normal cable.

The yard put the mast back and did the tuning. When arriving we noticed that we could not close the door toward the forward cabin any more. The yard was ready to adjust the wood of the door and blamed humidity. We said no thank for cutting our door but it took me some while to understand that the shroud were over tightened. We have since reduced the tension and the door could be opened nicely but we still have problem with the saloon floor.

Question:

Is it normal that by pulling the shrouds we have some hull deformation?
Should we go on untightening the shroud until we can open the saloon floor?
Should we reduce the tension when not sailing in the winter?

Thank for your experiences

 
     
 
 
30 November 2010 - 12:50
#6
 
  the professor Join Date: 02 January 2008
Posts: 873
 
 

Dear Ludovic
When the shrouds are pre-tensioned there is some deformation in the hull, but your description suggests that the deformation is excessive. However previous grounding damage may have damaged the structure in the keel area, and causes it to flex more.
I would like to ask whether you noticed to which heeling angle the leeward shrouds remained tight when sailing on the wind? If they did not slack at 30 degrees or more the pre-tension was excessive, if they slacked earlier the structure has softened.
It is suggested that you inspect the structure closely in the bulkhead/floorboard problem area in order to determine whether there is local damage and deformation.


Kind regards


Lars

 
     
 
 
30 November 2010 - 16:10
#7
 
  danielefua Join Date: 30 January 2007
Posts: 330
 
 
Dear Lars,

as always, you give a very interesting information that cannot go unnoticed.

Pretensioning is almost right when downwind shrouds become slack around a 30 degrees heel. Is this right? I guess this is also pretty independent of sail surface and wind velocity: given the ballast weight and hull geometry, heel angle is a function of torque only.

I have often thought of purchasing a tension gauge but the ones for the rod size I need are very expensive. You are proposing a much cheaper way and something one can check easily and often.



Daniel, 411/004
 
     
 
 
 
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