Rig tension

We have double Profurl on Shamrock, I understand the concept of testing rig tension when having access to the stays with hank-on sails, how do we get the rig tension correct when using roller furling? Anyone one figure this one out?


I discussed the topic of furler rig tension with Schaeffer Marine.
According to Schaeffer Marine, the tension on the stay should be tight
enough to prevent the furler from precessing around the axis of the stay
when the sail is furled or unfurled. Further, the furled sail will always
exhibit catenary regardless of the stay tension.


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From: “BCC Forums” bccforums@samlmorse.com
To: bccforum@samlmorse.com
Sent: Tuesday, April 19, 2005 1:47 AM
Subject: [BCC Forum Post] Shamrock: Rig tension


My rig comes down every fall here in the Great Lakes so I've fiddled with getting things true quite a bit.  I have a Spartite plug which locates the mast initially.  I then hook everything up with minimal tension.  I use a Loos gauge for tensioning the stays.  Unlike most, I start with the lowers and work my way up.  It has never made any sense to tension the fore and back stays first as you will induce a compression bend in the spar.

I have the boomkin stays tight enough to induce a minor down bend and locate the sprit by eye with a tiny up angle (later taken out to nuetral with the bob stay). I then work my way up the mast to about 75% of my end tensions keeping an eye on the rake (essentially zero rake with my full-batten main) and mast bend athwartships.
Now here’s my theory on getting the headstay close. I set the rake equally by feel (effort on the turnbuckle is a good clue) with the fore back stays. I now know what the turnbuckle on my head stay should look like but the initial theory assumed that if the head and back stay are about equal while setting the rake (maybe a little bias to the headstay) if I final tension the backstay to my desired tension, the headstay will end up with a similar tension being the other leg of the triangle.
Seems to work and the furler foil has a decent shape…nothing has gone “twang” yet.