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1110Re: [j4x-owners-group] Generic tuning question - pre-bend.

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  • William Stellin
    Nov 11, 2013
      As I recall, Hall Spars has a very good tuning and set-up guide for the J/42 rig.  My prebend is much more than 1 inch and I did shorten the head stay which turned out to be a big job because I had to shorten the Harken foil.  Cutting the foil is easy, the hard  part was shortening the internal connectors of the foil.   Rather than shortening the stay, I would have preferred moving the mast aft at the base but the idiots at TPI never used TefGel on the fasteners so the mast step was effectively welded to the aluminum cross beam.
      Shortening did help straighten the mast, but frankly I am not sure it was worth it.  The boat doesn't sail any differently that I can tell.  Also you have to be careful about sail hoist as an original sail before the shortening will now be to long on the hoist.  And with new sails be sure to tell the builder the head stay is shortenedl.  Even though they may actually measure the rig, they still use mfg. specs and some trust those spec's more than a physical measurment.
      Bill   #6

      Sent from my iPad

      On Nov 11, 2013, at 9:36 AM, "Barry Dwyer" <bdwyer@...> wrote:


      That 1” recommendation had me confused. I’m not sure I could get there w/o shortening the forestay. 



      From: j4x-owners-group@yahoogroups.com [mailto:j4x-owners-group@yahoogroups.com] On Behalf Of Thomas Keffer
      Sent: Monday, November 11, 2013 9:32 AM
      To: j4x-owners-group@yahoogroups.com
      Subject: Re: [j4x-owners-group] Generic tuning question - pre-bend.





      That North guide gives the prebend at "less than 1 inch," which sounds very small. Is this for the aluminum mast?


      The J/120s also commonly use checkstays.




      Tom Keffer

      +1 541-386-8891 (h)
      +1 541-490-9507 (c)

      Skype: tkeffer


      On Mon, Nov 11, 2013 at 6:21 AM, Bernard Coyne <coyneb@...> wrote:


      [Attachment(s) from Bernard Coyne included below]

      The J/42 rig is identical to the J/120 so I used this North tuning guide...


      Bernie Coyne
      Sr. Technical Marketing Manager
      DevOps Collaborative Development Practice
      IBM Software Group, Rational
      Phone:  720-396-6297
      Email:   coyneb@...

      DevOps for Dummies - Your free guide to faster, continuous software delivery

      From:        <bdwyer@...>
      To:        <j4x-owners-group@yahoogroups.com>
      Date:        11/11/2013 08:58 AM
      Subject:        [j4x-owners-group] Generic tuning question - pre-bend.
      Sent by:        j4x-owners-group@yahoogroups.com


      We have had our J/42 for about 5 weeks now and love her. Thankfully the PO had an espar heater installed when he bought the boat so we have used the boat every weekend here on the Chesapeake with our final weekend next week.

      Because the boat is coming out of the water soon this question may be better asked in the spring but It is very much on my mind so; how much pre-bend do you have in your rigs?

      There is a significant amount in ours (maybe 5") and in order to get the forestay tight (like when it was blowing 25 this weekend) I need to really pump up the backstay inducing what seems like too much bend.

      I have about 1.5" of thread showing below the furler so I think I can take some of the pre-bend out but I am almost thinking the forestay might be to long.





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