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Old 13-06-2010, 20:24   #1
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Jib Jabbery

Hello All,

I had Idora out yesterday and did a bit of beating. She is a ketch rig Ingrid. I am interested in the opinion of the group on what is the correct amont of sag in the forstay when close hauled. Judging by the amount of weather helm (very litttle) I think I have the correct amount of main mast rake and fore and aft bend (by sight).
I have heard that slacking the forestay slightly will aid cutter rigs to windward. Would this be true of a ketch as well? ( I do sail her with mizzen stowed to windward.) Obviously a full keel ketch rig will not point like a sloop (no worries). When I get her up to the mid 30 degrees apparent wind I am loosing power and getting a little main mast pumping that is induced by the roller furling jib oscillating under load. Curious what the group advises by way of adjustments to optimize the peformance of the rig. Also it looks as if the jib cars are properly placed.
Thanks,

Todd
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Old 13-06-2010, 23:52   #2
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Aloha Todd,
Best efficency is when the forestay is straight except in very light winds where a bit of belly in the sail gives it more power.
You may never get a perfectly straight forestay but get it as straight as possible in winds 12k and above.
You have the proper boom angle for the mizzen while close hauled. Just a little to windward.
regards,
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Old 15-06-2010, 08:52   #3
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Thanks John-

On my previous boat (a sloop) I kept the forstay as straight as possible. I will do the same on Idora. Both masts have dual backstays. I think a little more tension on those is in order. There is a very slight amount of tipping off on the main mast on the port tack so perhaps a bit more on the port upper. (The bend is above the intermediates) Also an increase in balanced tension on the lowers all around to dampen out the pumping. Nothing but fun...

Todd
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Old 15-06-2010, 09:59   #4
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Where sag can be helpful is with a yankee-style jib with a high clew. This is why cutters tend to want a bit of sag--because they tend to fly yankees on the headstay.

If you fly a conventional (low-clew) jib, less sag is desirable. With a deck-sweeper genoa, zero sag is ideal.
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Old 15-06-2010, 22:41   #5
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Wet decks

Thanks Bash-

It appears I have a semi Yankee jib. The clew is not parallel to the deck, it does angle up like a yankee. The roller furler is mounted on the head stay and the semi- yankee flies there. The length of the clew is relatively short making the sail quite high aspect ratio. I was not flying the stay sail on the inner stay on the day in question. I wonder if the yankee would be more stable if the stay sail was up and it was powering the slot between the two? There was about 17 kts of wind that day and that was plenty of power off the wind. I didn't think to try it. Seems I need to go out and experiment before I mess with the forstay tension..Hmmm.

Todd
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Old 15-06-2010, 22:58   #6
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Depends on the rig. Some rigs can take more tension than other before something breaks. You would never put as much tension on a wood mast as you would on a carbon fiber mast on a race boat. Hulls can also deform under too much rig tension. Hire a professional to come out to teach you how to tune your rig.
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Old 18-06-2010, 10:30   #7
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Thanks David,

Not to worry I'm not out there cranking daylights out of things. I already have some advice from a pro. He recommended increasing tension on the lowers and dual backstays but he has not sailed the boat. Frankly I have not sailed her enough myself. I am observing as I use her and tweaking as I go. Sorry if I sound like a newb but I am when it comes to this rig.

Todd
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