Addiing double diamonds to a Nacra 6.0 mast
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Posted: Jul 23, 2009 - 10:06 AM
I have a Nacra 6.0 orig and I would like to add a squaretop main. It seems that in its current configuration, the sqwuaretop will snap the mast on a decent blow.
I am considering adding an extra set of diamond wires to help the mast out. Has anyone done this?
How high up the mast would I put the upper(outer )set?
I would also add 60NA spreader bars in the spreaders current location, which is about 18 inches below spreader location on the 6.0NA. I dont want to comprimise mast strength due to drilling more holes in it.
The alternative is to find a NA mast. I would rather do everything I can with this one first. -
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Posted: Jul 23, 2009 - 12:35 PM
What is the difference between the original 6.0 mast and the NA? I thought the NA was just a bigger jib and jib foil.
I can't imagine a square-top snapping a mast. Square top sails have been added to many cats that were not originally designed for them. My Hobie 18 runs a square top with the original comptip (fiberglass top 6 feet) mast, surely your 6.0 mast is stronger than that.
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Damon Linkous
1992 Hobie 18
Memphis, TN
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Posted: Jul 23, 2009 - 12:39 PM
I know you said (on catsailor) that if you removed the current spreader, the empty rivits could weaken the mast.
I am no engeneer, but what about simple adding a second set (not internal) with a second spreader?
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Posted: Jul 23, 2009 - 01:45 PM
I don't see how adding a few holes to the mast as having a big impact on tht total strength of the mast. Especially if those holes are not near other holes. If you are adding additional holes right next to existing holes that would weaken it slightly, but if the holes are 6" or a foot away from other holes I would not think it would have any real impact on strength.
I have never used a squaretop sail, but don't they typically spill air off the top when the wind is really blowing? I remember hearing somewhere (no idea where) that is light to medium wind the square top really makes a difference but when it is really blowing the added sail area is not really a benefit since the top corner just rolls back and spills the air off. It made sense to me, and if that is the case in extreme conditions the squaretop wouldn't make that big a difference.
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Scott,
‘92 H18 w/SX wings
‘95 Hobie Funseeker 12 (Holder 12)
‘96/‘01/‘14 Hobie Waves
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Posted: Jul 23, 2009 - 03:26 PM
well the top still has a batten in it to keep it in place. yes it does twist off in heavy air.. but i am sure it still ads power in all ranges.
many of my co-sailors have pin tops for heavy air... -
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Posted: Jul 23, 2009 - 04:50 PM
We have a 6.0 here in Jackson, MS that is like yours. Single diamonds and a self tacking jib about a '91 boat. The original owner put a NA jib and a Hobie 21 spin on it. The second owner square toped it. So do I need to tell the current owner who's planing on getting a new square top that he may brak the mast because he only has one set of diamonds? I don't think you will break the mast just because you square top your main.
edited by: nacra55, Jul 23, 2009 - 05:11 PM
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Ron
Nacra F18
Reservoir Sailing Assn.
Brandon, Mississippi
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Posted: Jul 23, 2009 - 05:44 PM
the mast snapping warning comes from the maker -
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Posted: Jul 23, 2009 - 06:18 PM
Most every manufacturer will CYA and not recommend modifying their tested design in any way. The question becomes how big a safety factor do they use when designing something and do you want to operate in that safety factor.
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Scott,
‘92 H18 w/SX wings
‘95 Hobie Funseeker 12 (Holder 12)
‘96/‘01/‘14 Hobie Waves
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Posted: Jul 24, 2009 - 02:30 AM
That's kinda what I thought and then i spoke with skip elliot, and he said the same ting. Seems that the mast walls on the first few were pretty thin. then they beefed them up after they snapped a few off.
I may need to take the base off and mike the wall thickness and compare with manufacturers specs.
I put a sq on my 5.7 and had no problems, I think it had the lighter mast also.
If you look on youtube there is a video of a 6.0 mast folding up. sq top. "when the limit is exceded" is the title of the vid. -
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Posted: Jul 24, 2009 - 02:36 AM
The na has a thicker wall thickness also, Acording to skip, adding about 25%more mast stiffness. He said they normally break between the hounds and the diamond, not above the hounds -
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Posted: Jul 24, 2009 - 10:05 AM
one more thing is that the mast may have an insert to absorb the spreader pressure. your current spreader may have one but if you add a diamond it would not and could crush the mast at that point. Just a thought.
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FYC, Nacra 5.2 "Chris's Flyer" & Nacra Playcat & Farrier Tramp
Previously owned: Trac 14, H14, H16, H18, N5.0, G-cat 5.0
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