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#120197 - 10/14/07 07:22 AM More spinnaker questions  
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fin. Offline
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I'm not having much luck using the search engine. Anybody have the thread(s) that talk about tell tale placement and luff tension?

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#120198 - 10/14/07 09:34 AM Re: More spinnaker questions [Re: fin.]  
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Umm, this one?



F16 Blade 716
#120199 - 10/15/07 07:02 AM Re: More spinnaker questions [Re: bobcat]  
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That's one of them, thanks. However, it doesn't answer the question that's bugging me at the moment!

What is the proper luff tension? More specifically, what is the best tension for sailing deep. I have it in my head that most of us are sailing too high. Speed has become a sort of Holy Grail. I'm more interested in vmg.

Last edited by Tikipete; 10/15/07 07:18 AM.
#120200 - 10/15/07 07:51 AM Re: More spinnaker questions [Re: fin.]  
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Traditional theory says a loose luff helps you sail higher, so would a tighter luff let you go deeper? If so, grab the luff with your hand and be able to twist your hand a little less than 90 degrees. Maybe a good place to start?


Tom
#120201 - 10/15/07 08:55 AM Re: More spinnaker questions [Re: tshan]  
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I think the "best" luff tension setup for any given condition depends on too many different variables for a simple answer. Your sailmaker should be able to tell you what distance from pole to mast he designed the spi for, that would be the best starting point. Then experiment from there with two boat tuning.
On the Tornado we set up the distanse from pole to mast to be 9100mm whereas the max luff length is 9150mm (which the sailmakers never cut that long, as they know the cloth will stretch some and they need some margins of measurement/assembly error). 20-30mm of slack in the luff was our aim, or grab the luff and twist about 35-45deg before the luff becomes tight. This was on the Gran Segel model-4 spi. I am certain this will differ between sailmakers according to how they designed the luff and the rest of the sail.
If I had the money, I would definately have ordered a F-16 spi from Gran Segel in Malmų! As it is, I think most sailmakers cut their beachcat spis too deep with too much shape in the luff. A bit less shape and draft means the sail will become faster for less drag, but it might be bad for VMG if overdone. Only testing will tell, but the Gran Segel spis with their flat shapes and twist was a leap ahead on the Tornado when launched at the worlds at Marthas Vineyard in 2002 (not that I was there, but friends was..).

#120202 - 10/15/07 09:41 AM Re: More spinnaker questions [Re: Rolf_Nilsen]  
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Tom, Rolf: That's what I've been doing and I just can't shake the feeling it isn't quite right.

It's all Tim's fault! <img src="http://www.catsailor.com/forums/images/graemlins/laugh.gif" alt="" /> I had been content following Seth, Robi and Tback around the course, trying to close the gap. Then Tim comes along and waxes everyone!

His spinnaker work is much different than everyone elses. Unless my eyes deceive me, he is sailing much deeper with little if any difference in speed.

Maybe we can prevail on him. Tim! You out there?

#120203 - 10/15/07 09:53 AM Re: More spinnaker questions [Re: fin.]  
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If you have mostly the same gear and setup, Tim probably have the best technique for carrying the virtual wind with him when going downhull. <img src="http://www.catsailor.com/forums/images/graemlins/crazy.gif" alt="" />

#120204 - 10/15/07 10:00 AM Re: More spinnaker questions [Re: fin.]  
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All I know about sailing downwind with spinn I learned from Alex Shafer, John Casey, Jim Novak and a few other INter 20 experts. Also, in Rick White's book, Catamaran Racing for the 90's (it's time for an updated eddition, I think <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />) there is a whole chapter by Randy Smythe about spinnaker sailing techniques.

Here's what they all say: Put it up on one hull and keep it there. Do what ever you have to do, but keep it going fast on one hull until you get to the point where you might wipe out (stuff the one hull too deep).

The theory is; as you lift a hull, you will go faster, and then the aparant wind moves forward, so you go deeper, and faster, at the same time.

As far as luff tension, it is fully adjustable through both the halyard and tack line. A flatter luff will allow you to point higher, while a tighter luff works better for running deeper.

In light air, you want the spin luff flat to go higher, so you ease the halyard or tack line to get the luff flat, ie. no curl. You can move your weight inboard, keep your boards down, anything to get that hull up, then gently steer deeper as it lifts, but keep the hull up.

In more wind (like last week) you have no problem flying a hull, now not tipping over is the problem, so you are swithcing to de-power mode, which means a tighter luff, just like your mainsail, and you are going to sail deeper so you don't need such a flat entry to the spinn.

As I rounded A mark, I dumped the traveler quite a bit to be able to bear off and set the spinn (without steering the boat). As soon as the spin was up, I pulled the boards up about half way, brought the travler up to about 18" out, and then sheeted the kite in, while headding deep. Then I simply had to head up a bit to fly the hull, and as it came up, bear off enough to ride the fine line of keeping the hull up, but not too high. Kind of a delicate zig zag steering, with the pressure. I eased the downhaul and rotator to get the main right but other than that, never touched the mainsheet. I was sitting as far back as I could, and outboard, feet under the straps, butt cheeks right on the aft beam, to try to keep the nose up. There were a couple times I stuffed the bow deep and had to dump the spin sheet to keep upright, especially as I got closer to the leeward gate where the wind was stronger. There I was on two hulls more than one, to keep upright. And do not go off to a corner when the wind is up, you may not be able to cary the spin back to the gate if you get a big gust. It's better to gybe down the middle of the course (staying in the puffs) so you don't overstand.

I was able to hook into a single puff and ride it quite a ways before I had to gybe back to stay near the middle of the course. After the gybe, I head up again until the hull lifts, then ride the next puff on one hull as long as possible, gybe, repeat.

In bigger winds, when you really might eat it, keep it on two hulls to keep the bows from going too deep. Ease the traveler and keep the spin luff tight, which will de-power it, keep your board up, anything it takes to maintain control.

Swimming is slow.

Last edited by Timbo; 10/15/07 01:21 PM.

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#120205 - 10/15/07 10:45 AM Re: More spinnaker questions [Re: Timbo]  
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. . . Swimming is slow. [/quote] <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

Thanks Tim. That's sorta what I've been trying to do. But, not so well as you. <img src="http://www.catsailor.com/forums/images/graemlins/tongue.gif" alt="" />

#120206 - 10/15/07 11:44 AM Re: More spinnaker questions [Re: fin.]  
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The 'swimming is slow' thing was not directed at you personally, just a reminder that when you push it too hard, you can swim, and I've done more than my share of it. So when I go downwind in big air, I start out conservatively, going deep, then slowly heat it up, if it gets too wild, I go deep again, on two hulls. But I always try to push it up a notch or two when conditions permit. And this is my 4th spinnaker cat, so I've had 7 years to work on it here on my lake. There is definately a technique to it. Practice is the answer.

You caught me in that last race, I should be asking you what you were doing. I think I went to the wrong side of the course on the second beat. Did you go to the left side or right (looking upwind)?

Last edited by Timbo; 10/15/07 11:57 AM.

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#120207 - 10/15/07 05:35 PM Re: More spinnaker questions [Re: fin.]  
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Quote
Tom, Rolf: That's what I've been doing and I just can't shake the feeling it isn't quite right.

It's all Tim's fault! <img src="http://www.catsailor.com/forums/images/graemlins/laugh.gif" alt="" /> I had been content following Seth, Robi and Tback around the course, trying to close the gap. Then Tim comes along and waxes everyone!

His spinnaker work is much different than everyone elses. Unless my eyes deceive me, he is sailing much deeper with little if any difference in speed.

Maybe we can prevail on him. Tim! You out there?


weight on the boat can be important when going downwind. If there is more weight on one boat than the other then the heavier will have to run higher to get the hull up whereas the lighter boat may be able to run deeper and have the hull up as well. I noticed this when I was sailing with an HT being sailed solo (so, other than a crazy amount of sail area, it was kind of the same set up). The HT ran way deeper than me- simply because it had to actually. I had to come up higher to get more speed/generate apparent wind.

#120208 - 10/15/07 05:47 PM Re: More spinnaker questions [Re: PTP]  
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And the HT's mast is about 4-5 feet higher, up there in more wind. That helps a lot in light air, but hurts in big wind.


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#120209 - 10/15/07 08:40 PM Re: More spinnaker questions [Re: Timbo]  
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Tim: I didn't think the "swimming" thing was directed at me personally. The fact is, it is true, it's funny and I've done it many times. <img src="http://www.catsailor.com/forums/images/graemlins/laugh.gif" alt="" />

I sailed towards the center of the bay in that last race. I'd sure like for all of us to sit down with a chart and try to figure out what the wind was doing. I think there is a valuable lesson to be learned.

#120210 - 10/16/07 07:47 AM Re: More spinnaker questions [Re: fin.]  
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Are you obsessing when you reply to your own posts?

We had an unusual result in the 3rd race at GYC last race day. I think this is what happened:

Tim went through the gate first and headed out to the "Sargasso Sea", Seth/Todd were next and headed in to the North shore, Robi and Terry came through close together (can't remember who was ahead) and followed Tim [who was so far ahead they probably didn't see him] finally I made it through and started after Terry and Robi. I definitely had no idea where Tim was. I avoid the "Sargasso Sea", nothing good ever happens when I go over there. So, I tacked over to the middle of the course, and low and behold there is much better pressure and slightly better angle. The result was that I picked off everyone except Tim and Jennifer!

I still am having a hard time acccepting that there is this much wind advantage in such a small bay! The section of the bay we are using is about 1.3 x 0.9 miles.

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#120211 - 10/16/07 08:02 AM Re: More spinnaker questions [Re: fin.]  

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Pete,
I have been sailing Boca Ciega Bay for 6 year's now.
5 with my mono and 1 with my cat. It is a crazy bay, air is
all over the place especially with the condo swirl and bridge channels. Lot's of times there is a big hole in the middle and all kinds of wind on the edges and 2 far ends.
We are getting into the time of year when the gust really start to come in so watch out next weeekend.
I saw Robi and Stefan capsize 4 times in less then two
hours this Sunday but I think they were pushing just a little beyond the envelope.

#120212 - 10/16/07 08:08 AM Re: More spinnaker questions [Re: ]  
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Quote
. . .
I saw Robi and Stefan capsize 4 times in less then two
hours this Sunday but I think they were pushing just a little beyond the envelope.


ROFLMAO!!! <img src="http://www.catsailor.com/forums/images/graemlins/laugh.gif" alt="" /> I'm pretty sure adrenaline is their drug of choice.

#120213 - 10/16/07 08:29 AM Re: More spinnaker questions [Re: fin.]  
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Pete, thanks for posting that excellent picture of the bay, that makes it much easier to figure out, I think. It was my first time there but here's what I thought:

1. It seemed to me the wind was both stronger and from a better angle to the north side (top of photo).

2. The tide was going out all day, from that picture it looks like it would flow south under the bridges on the way out, is that true Todd? If that is the case, the north side would be better to sail less distance.

3. On the last leg of the last race, I had a problem snuffing my spin, I wasted quite a bit of time getting through the gate, and when it was over I was pointing to the south side so I just kept going that way. Huge mistake. Jenn rounded after me, she was at least 500 yards behind before I had the snuffer problem. She went north (again, like I had all day until that last leg) and then I tacked over to try to cover her, but when we came back together she was well ahead. That's how much favored the north side was.

4. The wind on that little bay is exactly like here on the lake. Lots of puffs, 30 degree shifts, etc. In those conditions there are no laylines, especially when A mark is up against a shore with swirling winds. So instead of trying to one-tack it out to the corner, a better strategy is to tack on every shift up the middle, favoring the side with better wind, less obstructions, less adverse current, what ever, but do not try to go to a layline far out from A mark. The layline will change at least 5 times before you get there.

Same thing going downwind. There are no laylines with that kind of wind. In a puff with the spin up, you will have to run deep, and if you are already on the layline, you will be overstood deep, maybe even have to drop the spin to get back to the gate, or try to go in on a high reach, which can lead to a pitchpole in the next gust.

It's blowing again today, I'm going out to practice some more, getting ready for Saturday... <img src="http://www.catsailor.com/forums/images/graemlins/blush.gif" alt="" />

Last edited by Timbo; 10/16/07 09:37 AM.

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#120214 - 10/16/07 09:09 AM Re: More spinnaker questions [Re: Timbo]  
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. . . 2. The tide was going out all day, from that picture it looks like it would flow south under the bridges on the way out, is that true Todd? If that is the case, the north side would be better to sail less distance.


Tony Kruse has been a member of GYC since 1970! He spends a lot of time on the North side, it is rare to see him out South.

C U Saturday. <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

Last edited by Tikipete; 10/16/07 09:10 AM.
#120215 - 10/16/07 11:11 AM Re: More spinnaker questions [Re: Timbo]  

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Quote


The tide was going out all day, from that picture it looks like it would flow south under the bridges on the way out,


Yes I believe that would be how it drains out.

#120216 - 10/16/07 11:26 AM Re: More spinnaker questions [Re: ]  
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So I guess I'll see all you guys on the north side come Saturday... <img src="http://www.catsailor.com/forums/images/graemlins/shocked.gif" alt="" /> <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />


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