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 Post subject: many H17 sail questions
PostPosted: Wed Sep 10, 2008 7:21 am 
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How do you know when your H17 sail is bad? I have a hard time getting the the top front side telltale to flow like the lower no matter how much I crank on the sheet. The sail has delamination and the 2nd panel from the leech looks like it has more tension in it than the leech panel. Attention to batten tension helped some, but I still can't get the leeward twist out of it - no way can I hook the top to windward. Will a new(er) sail help? or do they all twist off? Is this a "feature" of the comptip?

How safe is it to purchase a used sail with less delamination? Do they go bad then delaminate, or delaminate then go bad? What are the stages of the progression of the deterioration of a new sail? What does a racer look for as the first sign that his sail is too old. And finally - Has Hobie (or Hobie's supplier) modernized the adhesive used in the laminate so new sails will last longer?


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PostPosted: Wed Sep 10, 2008 9:52 am 
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michaellove wrote:
Has Hobie (or Hobie's supplier) modernized the adhesive used in the laminate so new sails will last longer?


Yes... many years ago the materials got better.

Sail shape / twist is affected by sheet tension, downhaul, outhaul, batten tension and traveler position.

More downhaul will cause the top to twist (sheet out).

The settings vary greatly on conditions and points of sail, so hard to tell you what to do.

But... you don't necessarily want the top hooked to windward. Maybe add some leech tell tails to check the air flow off the leech up there.

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 Post subject:
PostPosted: Wed Sep 10, 2008 5:59 pm 
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Quote:
The settings vary greatly on conditions and points of sail, so hard to tell you what to do.


What I do for close hauled in light air - light downhaul and outhaul, traveler centered, adjust course till both lower telltales flow back, set mast rotation, finally - sheet down till the upper frontside telltail flows like lower. Basic textbook trim. It's the last part that I can't do, I can't sheet the twist out. I assume the problem is my old, dead sail. I assume it SHOULD be possible to pull out too much twist and hook it to windward.

What I should do is replace the sail. The BIG QUESTION - but is it safe to buy a used sail that looks ok? What are the chances of finding a good used sail or should I bite the bullet and spend the $$$$$$$$$ for new. What do I look for in a used sail? What fails first? How bad is bad? how old is old? How much delamination is too much? Is a bit of mildew the kiss of death?

Don't get me wrong - This H17 is great fun. For $1000 I can't complain about the 20 year old sail. Am I foolish to think I can find a good used sail?


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PostPosted: Mon Jul 19, 2010 7:59 am 
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I broke down and bought a new HOBIE 17 sail and battens and now I am even more confused than ever. The old sail and the new could not be more different. Unlike my old stretched out sail, my new sail requires a strong pull on a 6:1 downhaul to get the luff wrinkles out. I now need more batten tension to flatten out the wrinkles along the pockets. Unlike my old sail, I can now get the windward telltails to act in unison. And now I can hook the upper leech to windward with too much sheet tension - all as one might expect from a new sail. What I don't understand is what the telltails are doing. My best upwind VMG happens with the windward telltails pointing straight up! If I foot down till they flow back at all I am heading 15 degrees down from the rest of the fleet and the leech telltails are sucking forward.

After my first meeting with other boats I took the advice in Phil Berman's book and set up the sail with the boat on its side to measured the depth and draft. I found I needed a lot more downhaul, batten, and sheet tension than I expected in order to get the sail to become winglike. I staked out the old and new sails and measured them and the most significant difference was in the luff curve. But I could not really get meaningful measurements from my new sail because it is so puckery from the tight new stitching. Measuring the old sail is easy since it is almost flat.

The measurement exercise gave me the confidence to go out and try again, but did not give me any understanding of what is wrong.

I am really confused, is this normal for a H17 sail? What am I doing wrong? I tweaked every control on the boat except rake and still the windward telltails were stuck straight up and the fleet was vanishing over the horizon. As a novice racer I didn't expect to keep up with national champions, but I would like to understand how to sail the boat. Any help, suggestions, or explanations with this would be greatly appreciated.


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PostPosted: Mon Jul 19, 2010 5:57 pm 
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Did you compare your sailshape to any of the other boats in the fleet?

It sounds like your sail may be a little over drafted. Maybe try a increasing the mast rotation and the downhaul tension to get it to flatten out. Increasing sheet tension will also allow you to point a little higher and cause the top of the sail to flatten. You have to be real careful about this though in light to medium wind because if you oversheet, you can hook the leech and stall the top of the sail. Many of the guys will travel out a few inches in light choppy breeze in order to prevent over sheeting.

One of the most helpful things I have found is to place two sets of telltails in the upper two panels. In light wind, I check these two sets often as they will tell you what the top of your sail is doing. Remember that sails stall from the tip down, so if the top of your sail is working properly, the lower section should be good. I use these top telltails much more than the stock telltails which I almost never use.

sm


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PostPosted: Mon Jul 19, 2010 7:40 pm 
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>> Maybe try a increasing the mast rotation.
I tried that, but perhaps I did not try in small enough steps.

>> travel out a few inches
Lost a few degrees of height, gained a slight speed increase but overall loss of VMG.

>> downhaul tension
Even though the breeze was moderate - I pulled the skin off my fingers at 6:1 with 5mm line.

>> if you oversheet, you can hook the leech and stall the top of the sail.
I checked for this by footing till the windward telltails would flow, checking that they would jump up in unison and adjusting the sheet tension till they did. But at that point, where the telltails on the windward forward third of the sail were looking good - the telltails on the leeward after third were stalling.

You suggest more telltails higher on the sail. I'll try it, there enough on there now that a few more can't hurt.

>> Did you compare your sailshape to any of the other boats in the fleet?
Only by eye from a distance, but when they went past me their telltails looked textbook perfect. I had to leave the regatta Saturday afternoon to fulfill an obligation. If I could have spent more time with the fleet I would have asked to either borrow a fast sail or to have a fast guy try mine. I think the best path will be to swap sails and do a boat to boat test.

>> It sounds like your sail may be a little over drafted.
I am beginning to think that also. Maybe too much luff curve or maybe the bolt rope and batten pockets were sewn in too tight or something like that.

Maybe the comptip has stiffened with age and no longer bends to fit the luff curve with downhaul tension? But usually things get floppy with age, not stiffer.

I am running out of ideas.

Thanks SM for the thoughtful response.


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PostPosted: Tue Jul 20, 2010 8:06 pm 
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Sounds like you are working really hard on this one... I would offer two further suggestions.

First, try not to hurry. There are many sailors like me, who after 20+ years still still struggle with the complexity of sails, so take a bit of time to work through each option. If you change all things at once you might get improvement without understanding the "why" part.

Second, I got a lot of help from reading some stuff by Avril Gentry. Google gentry tufts (link below) to get a few articles he has written. While I think there is some more modern stuff out there now this should give you insight into how sails & tell-tales work.

http://www.google.com.au/#hl=en&q=+gent ... 054c573dfd


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PostPosted: Wed Jul 21, 2010 8:03 am 
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I think you are totally overthinking this. You're paying more attention to the telltales than they deserve.

I've been racing 17s for almost 20 years and there are only two telltales that I pay attention to upwind - the ones on the very leech of the sail to make sure I'm not over sheeted.

Sail the boat without looking at the telltales all the time.


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PostPosted: Wed Jul 21, 2010 9:38 am 
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It's true that you definitely don't want to be fixated on getting all the telltails to flow all the time because it's virtually impossible to do. You need to spend 95% of your time paying attention to what is going on around you, not what your telltails are doing. The best sailors have a good feel for when the boat is moving well and only glance at the telltails occasionally if something doesn't feel right. One of the fastest racers I knew had one telltail on his mainsail (not one set, just one telltail). He had obviously developed such a good feel for the boat that he didn't need them.

That said, when you're learning, the only way to develop a feel for the boat is use the telltails to let you know whether what you're doing is right or wrong- just don't over do it. One or two well placed sets of telltails should be all that's needed.

sm


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PostPosted: Wed Jul 21, 2010 8:23 pm 
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I need to find someone to swap sails for boat to boat testing. This will answer the question about the problem being with the sail or elsewhere - in about 15 minutes on the water. Anybody in the Eastern PA /NJ/DE/MD area willing to help me out with this? The Corsica River event is this weekend. I am willing to travel anywhere between NY and VA.

I appreciate the link to the discussion about telltails ("Gentry Tufts"), and I also appreciate the advice about learning the feel of the boat rather than being fixated on telltails - I couldn't agree more.

Rick White's "Catamaran Sailing for the 90s" has a chapter on the H17 by Carlton Tucker that has been my main source of information on H17 telltails - pretty much like every other other boat - " ... front telltail acting up a little". There is also an article by Dan Kulkoski that goes over basic setting.

About how many lbs of pull on a 6:1 downhaul should be required to pull the wrinkles from the luff?


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PostPosted: Wed Jul 21, 2010 11:18 pm 
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"About how many lbs of pull on a 6:1 down haul should be required to pull the wrinkles from the luff?"

I believe that some sailors set up a series of marks where they set their down haul position according to the prevailing conditions and the rig of their boat. As far as I know, they don't calibrate by measuring the pull weight on the down haul. Tension on the down haul affects the draft of the sail, and it is sail shape that you are seeking. The degree of draft, or shape that you want will vary with conditions. That's why some sailors can alter the down haul as they sail - they can change sail shape as winds vary. It follows then that lbs weight (force) on a down haul is not a very helpful concept unless you need so much force it points to a fault in your rig.


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PostPosted: Thu Jul 22, 2010 5:02 am 
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>>not a very helpful concept unless you need so much force it points to a fault in your rig.

That is why I ask the question, I suspect my sail of being defective.
I probably should not have asked the question, The way to proceed from here is with boat to boat testing and sail substitution.


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PostPosted: Thu Jul 22, 2010 9:40 am 
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michaellove wrote:
Anybody in the Eastern PA /NJ/DE/MD area willing to help me out with this?


I'm hoping to do the Alter Cup qualifier at Trixies in a week and a half on my 17. Otherwise, I plan to do Spray Beach, Shore Acres, and Rehoboth regattas on my 17.
We could possibly take a look during one of these events. Otherwise, there are a lot of other knowledgeable 17 sailors in Div 11, so just ask around.

sm


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PostPosted: Fri Jul 23, 2010 6:23 am 
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srm - Thanks for the offer. I'll be at Trixies looking for help (not as a competitor) if I haven't found it sooner.


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PostPosted: Tue Sep 14, 2010 7:21 pm 
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The problem with my new sail was that the bolt rope was too short. Hobie said it had shrunk. Hobie repaired the sail by replacing the luff tape and bolt rope and it now looks and acts like a sail.
I still don't understand why the windward telltails point up so much, but it doesn't matter because I can now keep up with the fast guys until I make a mistake.


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