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Adjustable head sail rigging woes (3.7 NP Combat)

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Created by gbm91 > 9 months ago, 30 Apr 2020
gbm91
VIC, 57 posts
30 Apr 2020 5:51PM
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Hi everyone,

I recently bought a 3.7m NP Combat for the really windy days. Today I practiced rigging it as I knew I needed to set up the adjustable head to the correct length and would rather not have to do it in 40 knots of wind.

I'm rigging the sail on a 370 NP X9 Ultra Wave SDM mast which I think is from the same year. The recommended mast is 340cm but there is an adjustable head.

I have set my mast extension to 6cm as any smaller than that, the extension won't fit into the mast (the mast becomes too narrow and the extension itself is long (42cm)) .
Hence overall mast length incl. extension is 370 + 6 = 376.
Luff is 355.
Therefore 376 - 355 = 21.

I adjusted the adjustable head to 21cm, which happens to be the max length as there is a piece of fabric which stops you feeding more of the strap through the buckle.

I then downhauled the sail and observed the following:

- Very loose leech even when not downhauled all the way down to setting (see pic 2)
- Bottom batten has an "S "shape. If I reduce batten tension, wrinkles appear in the pannels. I also found it difficult to get enough batten tension back on to remove wrinkles. May need to de-rig to apply more tension.
- Batten curve of bottom 2 battens is opposite to what it should be (i.e batten curving towards me as if backwinded) but only on starboard tack.

From your experience, is this all normal or is something going on? Symptoms of using a longer mast?
Any effects on performance?
Any other advice regarding rigging this sail?

Thanks!

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Awalkspoiled
213 posts
30 Apr 2020 9:28PM
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To me it just looks over-downhauled by about 2-3cm. If you have to use that extension just release downhaul until battens are slightly overlapping the mast rather than pulled away from it. Don't worry too much about the S-Curve, it's actually advantage on the lower batten of a wave sail since allows you to depower on a wave. Jeff Henderson designs it into the HotsailsMaui wave sails in fact. If you have an old extension lying around you can sand down the head little so it'll go further up the mast, but buying a stubby just for this sail would be good - less likely to point-load and snap the mast. You don't need to worry about closing the gap on a 3.7 so a little air between the foot of the sail and the deck isn't a big deal either - look at the way US1111 used to rig his wave sails back in the 90s.

forceten
1312 posts
30 Apr 2020 10:08PM
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You have downhauled to the specs, I think I read that part correctly, the mast is longer, so stiffer.
A SDM , may have a piece of the equation, but if the mast bend curve is correct, it should have no to little effect.
I would bring the top in, shorter, give more extension on the bottom, and don't look at the numbers, look at the sail, as you rig it.
I agree it has too much downhaul, to my experience, half the wavey bits off the leach would be maximum to me.
this as rigged would have no range, useable power , not there.
comments generally regarded as BS.
NP are not user friendly to rig, at a large shop with a spaghetti box number of mast combos, we could not get a NP to set right, true that the proof is on the water not beach, but.
Some more recent NP, have been friendly to me, a Atlas , your Combat
i used a HotSails Maui mast, which is a good curve .
i don't like NP sails, those I've had , have been former rentals, clapped out, sun stretched.
not a prime reflection of the mark. I sold all off.
other advise: a sail that small gets used in high wind, no **** Sherlock.

You want it to perform as intended, it's already stressing you, unless you are a meme Er if the Red Bull Storm chase.
my 2 bits.
PS: YOUR post is amazing with the photo journalism.

gorgesailor
442 posts
1 May 2020 12:38AM
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The shape actually looks pretty good but agree, just a bit too much downhaul. I would get a shorter extension, or take the top cap off. If your 370 was RDM it would probably set closer to spec.

LeeD
3454 posts
1 May 2020 2:24AM
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As said by everyone, too much downhaul, unless it's blowing 45 knots.
And as said, take plastic cap off your base or cut it 6". Not good to use such a long extension inside the mast, as it runs inside causing a wear circle leading to a breakage.

Basher
390 posts
1 May 2020 7:21AM
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An adjustable head setting is meaningless unless the webbing is marked - and, even then, you'd need to allow for 'give' when the webbing gets wet.

So, all printed guide figures go out the window, and you have to rig initially by eye. And then you try the sail on the water, making adjustments as seem right, according to what you feel.

I'm not going to tell you how to rig your sail from a photograph on the internet. But some say you might have overdownhauled it, and they might be right.

If your extension is too long then buy a shorter* one, rather than cut it down. Or, if you are going to use this sail a lot, then buy a mast plug version.


*Radz do a basic 15cms extension, and it's cheap.

gbm91
VIC, 57 posts
1 May 2020 9:36AM
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Thanks for the advice everyone.

I've got an old mast cup which I never use lying around somewhere. This should at least avoid the possibility of breaking the mast due to the long extension.

I should be giving the sail a try today so I'll be back later with some feedback!

gbm91
VIC, 57 posts
1 May 2020 6:17PM
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Session feedback:
3.7m + 84L wave board

I used the mast cup with no extension and adjusted the head to approx 15cm. I downhauled to what seemed like a reasonable amount of loose leech (much less than in pics).

I came back after a couple of runs struggling to get planing. I reduced downhaul again which made things much better. Overall probably 4 cm less downhaul than in pictures.

Other than that, the sail felt great. I'm looking forward to using it again.

Thanks for the tips everyone.



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"Adjustable head sail rigging woes (3.7 NP Combat)" started by gbm91