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bolronck
Joined: 27 Jun 2011
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thombiz
Joined: 25 Jun 2007
Posts: 490
Location: Corpus Christi
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 Posted: Sat Apr 14, 2012 8:19 pm Post subject: |
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Has this sail been left out in the sun a lot? If it has been left out a lot, UV damage could make the sail materials weak. My honest opinion is this is not the case with this sail. It looks like you may have used too stiff a mast and tried to downhaul but the excessive force needed to downhaul it caused the rupture.
I've repaired nearly 6000 sails and don't see this kind of rupture very often. The sail looks too new to be a UV weakness unless it has been left out in the sun a lot. Next possible culprit after UV damage is too much force needed to get the mast to bend to the required arc. Notice that when the sail is fully downhauled, if you draw a line between the tack pulley and the top of the mast, along this line is where the downhaul force is most concentrated. This concentrated force is where the ruptures occured.
I see the kind of failure shown in Pic #1 when a mast slap occurs. A mast slap occurs when the rider falls forward and the mast slaps the water with high speed. This causes a shock wave to run up the sail's line of tension between the downhaul pulleys and the top of the mast until the tension becomes focused for whatever reason about 1/6 the way down from the top of the mast. I used to see this a lot in Prydes and Aerotech's, but not so much lately.
Bob T.
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bolronck
Joined: 27 Jun 2011
Posts: 16
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| Posted: Sat Apr 14, 2012 8:56 pm Post subject: |
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| thombiz wrote: | | Has this sail been left out in the sun a lot? |
Personally I never let it in the sun or the cold. I use this sail 4 time. Today was the first time where I put some tension on it. I bought it used. That was a demo or renting sail.
My mast is a "HOT ROD RDM BIG WAVE 97% Prepreg carbon 400". |
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thombiz
Joined: 25 Jun 2007
Posts: 490
Location: Corpus Christi
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| Posted: Sat Apr 14, 2012 9:10 pm Post subject: |
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The Hot Rod 400 mast should be a pretty good match to the sail. It is supposed to have a bend characteristic very similar to the Powerex 400 RDM, so now, I don't think the mast was too stiff. If the sail really was a rental sail, then it could have seen an extreme amount of UV in just a few months. this would cause the monofilm to become weak. Weakness in the clear monofilm would result in a failure as seen in the boom area. In Pic 1, I suspect the white monofilm failure lead to the x-scrim failure.
You can read about my experiment with 303 UV Protectant and sail materials and UV exposure here: http://groups.google.com/group/rec.windsurfing/browse_thread/thread/6ca126178bd38943/1b498b43439590d5?lnk=gst&q=303#1b498b43439590d5
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nw30
Joined: 21 Dec 2008
Posts: 693
Location: The eye of the universe, Cen. Cal. coast
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| Posted: Sat Apr 14, 2012 11:18 pm Post subject: |
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It was cooked by the sun before you got it, hope you didn't pay more than $100 for it. The top panel could be fixed but the window is history, it would need total replacement.
Better yet, get a better sail, you wouldn't want a total blow-out when you are far off shore, it happens with those crispy sails. |
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jingebritsen
Joined: 21 Aug 2002
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bolronck
Joined: 27 Jun 2011
Posts: 16
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| Posted: Sun Apr 15, 2012 11:28 am Post subject: |
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Interesting your study
| nw30 wrote: | | It was cooked by the sun before you got it, hope you didn't pay more than $100 for it. |
I paid it $200, the vendor said that it make me a gift and that she should charge $400 because this sail was in very good condition lol
Also, maybe this Norh Ice have a weekness because I have a friend who had the same problem when tensioning. |
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feuser
Joined: 29 Oct 2002
Posts: 1291
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| Posted: Tue Apr 17, 2012 12:57 pm Post subject: |
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| bolronck wrote: | Interesting your study
| nw30 wrote: | | It was cooked by the sun before you got it, hope you didn't pay more than $100 for it. |
I paid it $200, the vendor said that it make me a gift and that she should charge $400 because this sail was in very good condition lol
Also, maybe this Norh Ice have a weekness because I have a friend who had the same problem when tensioning. |
I am sorry you were taken for a ride here. The state of a sail can only be judged by the amount of hours it has spent in the sun, and where; and a shop cannot possibly answer to that as well as a private seller. Unfortunately, some buyers look for abrasions, model year, etc. only, but for monofilm (or any laminate) the clock starts ticking the moment the sail is out of the bag.
I have sold many demo sails after using them for a year and I can tell you that everyone who's bought sails from me got a much, much better deal. Beware of rentals or used sails that come from tropical venues - unless you're talking 8.5m sails from Maui, which are probably brand new 
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damel
Joined: 15 Jul 2007
Posts: 211
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| Posted: Tue Apr 17, 2012 2:05 pm Post subject: |
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| bolronck wrote: | I paid it $200, the vendor said that it make me a gift and that she should charge $400 because this sail was in very good condition lol
Also, maybe this Norh Ice have a weekness because I have a friend who had the same problem when tensioning. |
$200 is really cheap for a North Ice which indicates the vendor probably knew the sail had seen a lot of sun. If you payed $400 for it I would say show the vendor this thread and try to get $200 back.
North Sails is well known for using a large amount of monofilm in their sails, which results in an incredibly light and high performance sails but not a lot of durability. I would point out that the Ice comes in an xply version that is certainly more durable. Companies like Ezzy and Sailworks make bomb proof sails using xply & scrim. I feel that Goya, Simmer and a few others have found a good balance between high performance & durability.
When buying a used sail I would be cautious of any sails that are mostly monofilm. You can tell how fragile the monofilm is by pushing back and forth with a finger on either side of a panel, if you hear a lot of cracking or if the film feels brittle move on because the panel will probably blow up on the first big catapult. I can tell you from experience that most people try to get rid of a monofilm sail the year before the panels get brittle so they can sell it before its obviously past its time.
In the past 5 years there have been a lot of advancements in monofilm material that are making their way to the windsurfing industry. They use multiple layers that cross invisible microfibers and infuse the material with UV protection, sunscreen basically. All that said I still caution away from monofilm sails.
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feuser
Joined: 29 Oct 2002
Posts: 1291
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| Posted: Tue Apr 17, 2012 4:14 pm Post subject: |
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| damel wrote: |
$200 is really cheap for a North Ice which indicates the vendor probably knew the sail had seen a lot of sun. If you payed $400 for it I would say show the vendor this thread and try to get $200 back.
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$200 for a sail that lasts a season may be okay, but $200 for a sail that tears upon rigging is exactly $200 too much, IMHO.
| damel wrote: | ...
In the past 5 years there have been a lot of advancements in monofilm material that are making their way to the windsurfing industry. They use multiple layers that cross invisible microfibers and infuse the material with UV protection, sunscreen basically. All that said I still caution away from monofilm sails. |
I agree with most of what you've said, but this is news to me. The only way to protect monofilm from UV is by tinting it, AFAIK (Point7 uses Yellow and Black). I am not aware of invisible fiber structures embedded into clear film. What makes laminate (x-ply) so much more resistant is the UV inhibitor in the glue between the layers and, strangely, the fact that the individual layers are so thin that they can bend over smaller radii without breaking. Remember, monofilm is a monolithic sheet of polyester that really doesn't like bending per se. The minimum bend radius is directly related to material thickness.
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florian - ny22
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