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#259389 - 05/07/13 08:37 AM Re: Sail setting and sailing techniques [Re: Arjan13]  
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samc99us Offline
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Arjan please read this thread: http://www.catsailor.com/forums/ubbthreads.php?ubb=showflat&Number=259280&nt=3&page=1

Twin wire jib reaching is the most difficult point of sail. You need to drop traveler and the crew should be playing the main sheet.


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#259391 - 05/07/13 08:48 AM Re: Sail setting and sailing techniques [Re: northsea junkie]  
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Arjan13 Offline
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@Northsea

Mast rotating was indeed as tight as possible. And what you describe here is a little bit where I'm afraid of. But reading your input, we might be able to fix it a little.

Just to be sure: After measuring the sail in this way: I suppose we measure the mast in the same way? (with the rope?)And the aim of the whole exercise would be to get it as close as possible?

@ Sam

Yes I'm starting to realize the subject of that topic is rather the same, but didn't understood that before because of the terms used (e.g. jib reaching) I will read it!

Last edited by Arjan13; 05/07/13 08:53 AM.
#259392 - 05/07/13 09:06 AM Re: Sail setting and sailing techniques [Re: Arjan13]  
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samc99us Offline
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You can do the measurement tricks but I'd start with your spreaders 50mm aft of the mast track as noted in the Nacra Infusion setup guide (yes I know it's a Inter 18 mast that is likely carbon, I don't have numbers for those). You want your diamonds cranked close to 43 on the Loos gauge if you're in big breeze.

Finally you might want to talk to your sail maker some about the measurements of luff curve.



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#259394 - 05/07/13 10:50 AM Re: Sail setting and sailing techniques [Re: Arjan13]  
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northsea junkie Offline
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Arjan, yes you can measure the prebent of the mast also with a rope from the top and then charging it with your weight in order to get the mastcurve under sail-load.

But remember there will always be (and it ought to be also!) a difference between your luffcurve of the sail and the mastcurve.
Exacly this diffence creates the (so-called external) camber of the sail. In other words, this makes a (vertical) wing of your sail!!

So the sail is always rounder then the mast! But not too much ! (around 5 cm difference is common, I believe)

By the way, in windsurf sails there are even sails who don't have any internal-camber (curving the sail by the sewing of non-linear seams) and get their profile purely out of external camber.

Twist in windsurfing sails is the most important factor.

Last edited by northsea junkie; 05/07/13 12:18 PM.

ronald
RAIDER-15 (homebuilt)

hey boy, what did you do over there, alone far out at sea?..
"huh....., that's the only place where I'm happy, sir.
#259397 - 05/07/13 12:23 PM Re: Sail setting and sailing techniques [Re: Arjan13]  
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Originally Posted by Arjan13

- At this course we're standing all the way on the back. The helmsman with one foot on the other site of the beam, standing close together trying to hold the boat in a diagonal way


Is the crew astern of the helmsman?

From what little I know of jib-reaching in higher wind on "short" boats (under 6 meter), flat is fast...

Boards up 1/2 way or higher (depending on water conditions) and both crew as far back as possible.

Sometimes the crew can get astern of the helm...sometimes (Alex & Nigel could figure that out). All that weight in the back helps keep the bow out of the water...

Traveler out a bit and mainsheet in hard. Both should be ready to ease at a moment's notice if the bow dives into a wave.

I guess the real debate centers on any steering change during the dive... should you steer upwind to depower, or downwind to change the wind angle?



Jay

#259400 - 05/07/13 02:40 PM Re: Sail setting and sailing techniques [Re: waterbug_wpb]  
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Arjan13 Offline
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No the crew is not astern of the helmsman. We never tried this. Seems a little difficult while the crew is handeling the sheet? (don't know if this works out)

But I do understand from the reactions that far back is normal here. (even a little bit further then we did)

But a question which I still have left is: When you are in strong wind, and the boat is constantly lifting (have to give a lot of sheet getting it down) What do you do first? get the boards up, or putting the traveler more out?

#259401 - 05/07/13 04:15 PM Re: Sail setting and sailing techniques [Re: Arjan13]  
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Jake Offline
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Originally Posted by Arjan13
No the crew is not astern of the helmsman. We never tried this. Seems a little difficult while the crew is handeling the sheet? (don't know if this works out)

But I do understand from the reactions that far back is normal here. (even a little bit further then we did)

But a question which I still have left is: When you are in strong wind, and the boat is constantly lifting (have to give a lot of sheet getting it down) What do you do first? get the boards up, or putting the traveler more out?


If you are reaching, you don't need the boards nearly as much - raise them half way for a reach regardless of power level (unless it's really light). The traveler will probably already be down some - but keep dropping it to try and control power. You still want to try and flatten the mainsail as much as possible with sheet tension.


Jake Kohl
#259411 - 05/08/13 08:49 AM Re: Sail setting and sailing techniques [Re: Jake]  
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I believe if you have to sheet out (mainsheet) more than about a full arm-length of line during a "lift" (or puff), you should adjust the traveler down a bit.

Of course, if conditions are really harsh (like huge puffs), you just have to work it as best you can with combination of travler, sheet, and steering.


Jay

#259521 - 05/10/13 08:49 AM Re: Sail setting and sailing techniques [Re: Arjan13]  
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Arjan13 Offline
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Besides the fact that most probably we have to search in our own sailing techniques and boat settings. This week we measured the old set of sails with the new ones. We did it with the line as described by Northsea, but we also put them on top of eachother and individually put some force on it. Now you can see that the main indeed differs from the old one, but to our surprise the new sail has a little less luff curve than the old one. (allthough the difference is only a few cm's (about 3-4 at the max)There is only a difference in the 2nd half of the sail Measuring with the line shows that the total curve is over 10 cm.


[Linked Image]

The difference between the old and new jib is bigger. We came from an original jib, and replaced it by a self tacking jib (much smaller) The jib is identical top down, but misses the last 20 cm's. (this is normal with self tacking?)


[Linked Image]

After that we measured the spreader, and measured 55mm, which could be right reading about the infusion settings and our relative low weight. But is this also right for the Inter? Is there anybody who can tell?

After that we wanted to adjust the tension on the diamant wire. But this wasn't used for some years, and therefor got stuck a little. Wew had to put some force on it (only little) but doing that the whole connectionplate came out of the mast. So we have some renovating to do.

Last edited by Arjan13; 05/10/13 08:51 AM.
#259526 - 05/10/13 01:25 PM Re: Sail setting and sailing techniques [Re: Arjan13]  
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northsea junkie Offline
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Arjan, so the upper half of the top of your new mainsail is a little flatter then your old sail.
I'm puzzeling at this moment what consequences this could have. It's in the part of your mast which is not supported by shrouds anymore, so the part that bents.

Overall you measure about 10 cm luffcurve; that's not a wrong figure. But it depends ofcourse of your mast.

I used to sail to sail on a (soft) P15 mast a mainsail with 15 cm curve. But then I changed to a sawn-off P18 mast which was very stiff (curve 1,5 cm). I modified the sail to 11 cm curve, but it was still far too much.
Now I sail with a main with 7 cm luffcurve and that's perfect.

This doesn't help you much but give you perhaps a little bit of feeling for the figures.
The difference between the mastcurve and the luffcurve of the sail is considered to be one of the secrets of the sailmakers; they all use their own secret number. It is indeed about centimeters.

Maybe your top cannot open enough?. Looking at your original video of this thread, I see less twist in the upper part as compared to my sail. I know that a lot of sailors think that a flat and tight sail is the best. But without movable waterballast like on the Imoca boats, twist in the sail is our only safety valve for overpressurizing the sail.

As you can see in the little vid which I placed in the thread about jibreaching, I have (at the ingoing course) also difficulty too to keep my leebow not to be burried in the water.




Last edited by northsea junkie; 05/11/13 03:28 AM.

ronald
RAIDER-15 (homebuilt)

hey boy, what did you do over there, alone far out at sea?..
"huh....., that's the only place where I'm happy, sir.
#259535 - 05/11/13 02:38 AM Re: Sail setting and sailing techniques [Re: Arjan13]  

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Quick hint. When tightening your diamond wires, take them off the spreaders, make the change then put them back on. It's fiddly but you'll do less damage.

#259545 - 05/12/13 05:40 AM Re: Sail setting and sailing techniques [Re: ]  
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Jake Offline
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Originally Posted by Scarecrow
Quick hint. When tightening your diamond wires, take them off the spreaders, make the change then put them back on. It's fiddly but you'll do less damage.


Damage to what?


Jake Kohl
#259546 - 05/12/13 06:10 AM Re: Sail setting and sailing techniques [Re: ]  
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Originally Posted by Scarecrow
Quick hint. When tightening your diamond wires, take them off the spreaders, make the change then put them back on. It's fiddly but you'll do less damage.

Doing this on the water could be challenging. eek

#259547 - 05/12/13 06:35 AM Re: Sail setting and sailing techniques [Re: ]  
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Originally Posted by Scarecrow
Quick hint. When tightening your diamond wires, take them off the spreaders, make the change then put them back on. It's fiddly but you'll do less damage.


¿Que?

Is it even possible for anyone but Chuck Norris to install the wires on the spreaders with proper tension?

#259553 - 05/12/13 05:06 PM Re: Sail setting and sailing techniques [Re: Arjan13]  

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If you have modern diamond adjustment (big threads) it is not a big deal but on older boats (like I suspect the Inter) you can easily strip threads on the turn buckles when adjusting.

Here is a resource

[Linked Image]
Photo is from the AHPC Viper tuning manual, there is no need to be Chuck Norris.

Attached Files
spreader.jpg (129 downloads)
Last edited by Scarecrow; 05/12/13 05:07 PM.
#259555 - 05/12/13 05:42 PM Re: Sail setting and sailing techniques [Re: Arjan13]  
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But why would you do that??

#259556 - 05/12/13 06:08 PM Re: Sail setting and sailing techniques [Re: Arjan13]  

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It takes non-design loads off things. Arjan ripped the mount at the base of the mast out of his mast when tightening the diamonds. Probably because when doing up turnbackle the rivets holding it in place were put in tension rather than shear by the lever from his spanner. Had the wires been removed there would have been no load on this fitting during tightening and when the load was re-applied the rivets would have been in shear and possible would have stayed in place..

#259558 - 05/12/13 07:40 PM Re: Sail setting and sailing techniques [Re: ]  
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Jake Offline
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Originally Posted by Scarecrow
It takes non-design loads off things. Arjan ripped the mount at the base of the mast out of his mast when tightening the diamonds. Probably because when doing up turnbackle the rivets holding it in place were put in tension rather than shear by the lever from his spanner. Had the wires been removed there would have been no load on this fitting during tightening and when the load was re-applied the rivets would have been in shear and possible would have stayed in place..


Thanks, but not for me. I had to do that with my A-cat and I hated it so I never changed them once I had them set at a medium setting. I had to wear gloves and put feet on the mast to get the diamond wires out to the end of the spreaders and even then it took me one rummy per side to get it done. To try that on an aluminum mast running more tension I think is just nuts. If you're adjustment system fails when adjusting it, it needs to be redesigned and/or fixed. The Infusion system (and the older I20 system) are perfectly happy being adjusted at the diamond wire adjusters and without pulling the diamonds off the spreaders.


Jake Kohl
#259559 - 05/12/13 07:42 PM Re: Sail setting and sailing techniques [Re: Arjan13]  

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Thats the point his system did fail.

#259560 - 05/12/13 09:12 PM Re: Sail setting and sailing techniques [Re: Arjan13]  
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His system didn't fail. The inter 18 is a pretty old boat, close to 15 years I suspect. Turns out rivets corrode....

Didn't intend to be a dick either, but rivets do fail and more than likely the carbon around the rivet failed. Had this happen on a N20 carbon spin pole last year.

Last edited by samc99us; 05/13/13 07:56 AM.

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