[C38] head stay tension

Don Strong drstrong at ucdavis.edu
Tue Jun 25 14:24:21 EDT 2013


Ray: Dunno about pinning at the partners. The PO had new rigging done by 
a big shot.
Maybe some one else can figure this out

On 6/25/13 11:02 AM, Ray Torok wrote:
> Don:
>
> Interesting.  Do you know if your mast was free at the partners when 
> the rig was tuned?
>
> I'm worried that my mast is pinned at the partners with too little 
> mast rake and too little headstay tension, so the only way I can get 
> adequate headstay tension is by cranking on the backstay.  With the 
> backstay at 1000 on the gage (I'm not sure what that means really), I 
> have quite a bit of mast bend, and not that much headstay tension. 
>  This discussion is making me think I need to either shorten the 
> headstay a bit or let the mast come back more (increase rake) at the 
> partners and adjust the lower shrouds accordingly.  The alternative is 
> to let the forward lowers pull the middle of the mast forward while 
> the backstay pulls the top back to establish both headstay tension and 
> mast bend.  I have to believe someone has solved this problem.
>
> Thanks,
> Ray
>
>
> On Tue, Jun 25, 2013 at 10:44 AM, Don Strong <drstrong at ucdavis.edu 
> <mailto:drstrong at ucdavis.edu>> wrote:
>
>     Mark:
>       The winds are such that we go to weather when embarking on a
>     sail from the east SFB. Before leaving the dock, I tighten the jib
>     furler by means of the jib sheet led to port winch on the mast. If
>     you don't have a furler, then you would perform this tightening
>     when you raise the jib. Then I then put 1000lbs of tension on the
>     back stay adjuster. This places more tension on the jib furler,
>     which one can see easily in reduced sag and sway of the furled
>     jib; 1000 lbs of tension gives a taught, furled head sail even in
>     a seaway. The backstay tension greatly improves the performance
>     going to weather. I echo the advice of your rigger. Too much
>     backstay tension will bend the boat. It causes the head door to
>     jam shut on Discreet Charm. 1000 pounds on the gauge of our
>     backstay adjuster does not change the shape of the gap between the
>     head door and the frame.
>       When we head home, I release the backstay tension. This improves
>     performance before the wind.  I release tension on the jib furler
>     before disembarking.
>
>     Others on the list are much more accomplished sailors than me, and
>     will give more sophisticated advice.
>     Regards, Don
>
>     On 6/25/13 10:12 AM, Ray Torok wrote:
>>     Adding to the discussion - If the forward lower shrouds are tight
>>     and/or the mast is pinned at the partners, the backstay will
>>     impart all kinds of mast bend, so I don't understand your
>>     rigger's statement.
>>
>>     Ray Torok
>>     Thira #37
>>     San Francisco
>>
>>
>>     On Tue, Jun 25, 2013 at 10:06 AM, Mark O'Dell
>>     <mixedbusinesscontact at gmail.com
>>     <mailto:mixedbusinesscontact at gmail.com>> wrote:
>>
>>         Sorry that this might be a bit of a tangent, but Ray's
>>         question below sparked another semi-related question that I have:
>>
>>         Last year I had my spreaders re-angled, my rig inspected and
>>         tuned. (Ended up replacing the shroud extension cable that
>>         comes through the hanging locker, as it was microscopically
>>         cracked in a few places on the swauge).
>>
>>         Anyway, these people told me something interesting, in that
>>         they said said we don't have a mast that will have much bend
>>         to it.. so be very gentle with the backstay adjuster.  (They
>>         went so far as to making me a limit indicator on the adjuster
>>         that "I shouldn't" exceed. )
>>
>>         They're telling me that our masthead rig isn't really bending
>>         the mast much at all... it's just pulling the mast down on
>>         the keel step harder and harder.
>>
>>         I will also say that even if I exceed their "limit" my head
>>         stay is still sagging more than I think it should. +6"
>>
>>         Do you guys go above 2k lbs of pressure? 3k? What you're setting?
>>
>>         Is my mast rake out of whack?
>>
>>         Mark O'Dell
>>         Momentous #230
>>         Baltimore, MD
>>         http://www.c38momentous.com
>>
>>
>>
>>
>>         On Jun 25, 2013, at 12:52 PM, Ray Torok <torok13731 at gmail.com
>>         <mailto:torok13731 at gmail.com>> wrote:
>>
>>         > All:
>>         >
>>         > After repairing my lower spreaders, I have to retune the
>>         whole rig.  Are there recommended settings for mast rake,
>>         pre-bend and that stuff?  Also, is there a recommended tuning
>>         procedure (several are out there on the internet)?  Should I
>>         remove the Spartite plug at the partners to start?  I have no
>>         idea if the original setup was okay.  In fact, without lots
>>         of backstay (and mast bend), the headstay seemed awfully
>>         slack to me.  Any thoughts/advice/experience would be
>>         appreciated.
>>         >
>>         > Thanks,
>>         >
>>         > Ray
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>
>     -- 
>     Donald R. Strong
>     Professor,
>     Department of Evolution and Ecology
>     and
>     The Bodega Marine Laboratory,
>     University of California, Davis,
>     Davis CA
>     95616
>     530 752 7886  <tel:530%20752%207886>
>
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-- 
Donald R. Strong
Professor,
Department of Evolution and Ecology
and
The Bodega Marine Laboratory,
University of California, Davis,
Davis CA
95616
530 752 7886

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