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Rounding up question
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Sacandagalady



Joined: 28 Oct 2003
Posts: 39

PostPosted: Thu Aug 30, 2018 12:29 pm    Post subject: Rounding up question Reply with quote

So today I decided to downhaul my Ezzy 8.5 sail to the maximum setting suggested when usually I go 2 -4 cm less downhaul. I was looking to gain an area under the sail foot? to have room to tack more easily. Plus, I left the outhaul where I normally do and didn't add any additional outhaul for the additional downhaul.

The luff sleeve was really tight against the mast opening where I usually put my hand into to tack when normally it is much "looser".

Board: 145 Mistral explosion, Curtis weed fin (can't remember the cm's, but have used the same one without difficulty in the past.) Harness lines, either 26 or 28, seat harness, intermediate ability.

Usually I feel really comfortable where everything gets put, but because I changed things up, the board kept rounding up even when I was not in the lines. Going downwind was hell. I didn't know whether the lines were to far forward or back or if it was just the additional outhaul and slighter downhaul.

If anyone has any ideas, I would love to hear from you. Other than that, as I said, I have always felt great where everything was and have planed successfully in regular or gusty winds without any probs whatsoever. BTW, I am on a lake with up and down winds and the winds were on the lighter side with some planing and some shlogging.

Sacandagalady

Thanks in advance
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swchandler



Joined: 08 Nov 1993
Posts: 9109

PostPosted: Thu Aug 30, 2018 1:21 pm    Post subject: Reply with quote

More downhaul changes the shape of the sail (increasing the boom length between the mast and the clew), thereby necessitating adding more outhaul to tension it and properly establish the foil's shape. The important thing to remember is that as you increase downhaul, the shape of the foil lengthens at the clew and narrows in the power zone.

Although you don't have Sailworks sail, their rigging instructions on their website for the Retro depicts how downhaul changes for light, medium and strong conditions changes the look of leech in the upper sections of the sail. And, in addition, they also offer cross section views of the foil shape (at the sail's power zone) for the 3 different wind conditions. They do a good job of explaining things that generally will apply to any sail brand.
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nw30



Joined: 21 Dec 2008
Posts: 5074
Location: The eye of the universe, Cen. Cal. coast

PostPosted: Thu Aug 30, 2018 1:36 pm    Post subject: Reply with quote

Or you can go straight to an Ezzy source for rigging.
https://www.youtube.com/watch?v=Ur9i6dJPeEY
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dhmark



Joined: 04 Sep 2007
Posts: 273

PostPosted: Thu Aug 30, 2018 2:09 pm    Post subject: Reply with quote

I don't understand the reason that you decided to max downhaul, should simply be based on wind strength, but without additional outhaul the draft of the sail probably too far back, especially when the sail is not fully filled out.
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DanWeiss



Joined: 24 Jun 2008
Posts: 2244
Location: Connecticut, USA

PostPosted: Thu Aug 30, 2018 3:58 pm    Post subject: Reply with quote

You rounded up because the sail's draft was farther back than normal due to the dh added and lack of outhaul. This keeps the draft back and forces you to move the mast foot forward, assuming everything else was good to go.

However, because you notice a large enough change in the luff sock tension, I'd bet that you never had enough dh in the first place for the actual intended range of the sail. DH adjustment usually limits itself to one or two cm of actual distance of the sail on the mast. You wouldn't notice a change in luff sock tension just by feel at the boom opening when properly rigged.

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Sacandagalady



Joined: 28 Oct 2003
Posts: 39

PostPosted: Thu Aug 30, 2018 6:28 pm    Post subject: Rounding up Reply with quote

Thanks so much to all who have replied. Perhaps if I had outhauled the sail more, it would have acted more in line with what I was used to.

The tips and explanation really helped and suggestions of rigging at the websites makes great sense.

Today I went out and left the extension at the minimum suggested, outhauled well and off I went in the 12-18 mph wind range. What a big difference, and things felt right again. Outside of having to deal with pesky weeds even far from shore, once away from them I planed nonstop and eventually had to call it a day due to some fatigue and having the good enough sense to not push it.

I guess the fact that I'm out sailing at my age (63) and still improving is more than I could hope for.
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NOVAAN



Joined: 28 Sep 1994
Posts: 1041

PostPosted: Thu Aug 30, 2018 7:02 pm    Post subject: Reply with quote

I have been riding Ezzy sails since and before he started his own company.
I sell my sails every year and get a new quiver. I suggest to everyone that in order to get the most out of their sail, Go on line and watch the rigging and tuning video's that mister Ezzy provides. If your still having issues you can take a picture of your fully rigged sail and send it to Dave. He will respond quickly and make sure you get you sail set up correctly. Cheetah's are really good sails. Rounding up wind can be a lot of different things. Weed fins are notorious for doing that. By down hauling you put more curve in your mast and that moves the draft back. That might over power your fin and make you round up. On all Ezzy sails, in order to have a lite balanced sail, you need to match your out haul to your down haul. Positive out haul tension helps drive the draft forward. Your sail has 3 strings on the clue end. These are used to set the proper out haul into the sail. Again watch his video's and you will understand how it all works...
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U2U2U2



Joined: 06 Jul 2001
Posts: 4803
Location: Shipsterns Bluff, Tasmania. Colorado

PostPosted: Thu Aug 30, 2018 7:03 pm    Post subject: Reply with quote

I would have a better visual if I knew which 8.5 it is
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NOVAAN



Joined: 28 Sep 1994
Posts: 1041

PostPosted: Thu Aug 30, 2018 7:11 pm    Post subject: Reply with quote

I was out and sailing today in 18 to 22 mph winds. 5.8 Ezzy Zeta 96 Tabou 3s. I'm 68 years old, been windsurfing since 1981 and I learn new stuff all the time. Enjoy the ride go out and sail every chance you get even if the wind is lite...
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DanWeiss



Joined: 24 Jun 2008
Posts: 2244
Location: Connecticut, USA

PostPosted: Fri Aug 31, 2018 4:01 pm    Post subject: Reply with quote

NOVAAN wrote:
SNIP By down hauling you put more curve in your mast and that moves the draft back. SNIP


All correct and valuable info, NOVAAN, except for the conclusion in your text above. Downhaul does bend the mast but moves the draft forward due to seam shaping and skin tension assuming the sail is tuned for lighter wind. Thus as a general rule, adding DH when overpowered will move the draft forward (measured when the sail is inflated with wind) and reduce the rotational lift we feel and know as back hand pressure. Matching OH is a great idea as it moves the draft back and further reducing its depth. These two together keep the draft in the sweet spot along the boom and work to prevent the draft from moving back, all at the expense of raw power as we usually define it.

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