Author Topic: spreader sweep Carbon rigs  (Read 2260 times)

Doug Johnstone

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spreader sweep Carbon rigs
« on: August 16, 2014, 07:12:42 PM »
The spreader sweep on my boat is the most aft setting.  There are two available hole settings on each side of the mast bracket to allow the spreaders to go forward in sweep angle.  Curious to hear what other Viperers (?) are setting the spreaders at and how are you measuring.  I.E. Distance between spreader tips (excluding shroud inserts) or some other method.

I am aware of the effects of pre-bend on main shape, and sweep on pre-bend.  Just trying to get some numbers. 

Cheers,

Doug.
V  GBR-138

John Leyland

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Re: spreader sweep Carbon rigs
« Reply #1 on: August 17, 2014, 12:12:51 AM »
Hi Doug,

It may depend on your sails.  We have North and use their tuning guide where it lays out how to measure.  See http://www.onedesign.com/Portals/106/docs/Tuning%20Guides/north-viper-tuningguide.pdf

This resulted in us using the forward holes and reducing sweep angle but had to drill them out a little to accommodate the standard bolts.

Cheers,
John
Viper 191 - "Moistened Bint"
Vancouver, BC

Jeff Jones

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Re: spreader sweep Carbon rigs
« Reply #2 on: August 17, 2014, 12:07:46 PM »
If you sail heavy, min sweep.  If you sail light, max sweep.


Doug Johnstone

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Re: spreader sweep Carbon rigs
« Reply #3 on: August 17, 2014, 01:27:50 PM »
If you sail heavy, min sweep.  If you sail light, max sweep.

Interesting response that I didnt expect.  Why?

John L, thanks for the link.
V  GBR-138

Jonathan Nye

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Re: spreader sweep Carbon rigs
« Reply #4 on: October 20, 2014, 09:23:25 AM »
Long time no reply so for what it's worth...

With min sweep, as you apply shroud tension this pulls the spreader tips back (reducing shroud deflection). This in turn pull the mast at the spreader bracket back which straightens the mast and tightens the headstay keeping the sail plan from becoming overpowered.

Conversely, max sweep allows the middle of the mast be bend more easily so pre-bend is possible resulting in a softer headstay all things you want in lighter air. The way to accomplish this with min sweep is to go with less shroud tension.