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Old 24-01-2007, 15:57   #1
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Loose shrouds

I own a new Fountaine Pajot Athena 38 and while sailing close hauled or close reach the leeward shroud becomes very loose and flops about and will snap tight again with a shudder if the load suddenly comes off the sail. I was told this is normal by the guy who tuned up the rig and he suggested using a bungy cord to stop the shroud flopping around on long passages. Can any one out there give me advice if this is normal on a cat, or does it sound like my shrouds are too loose?

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Crak
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Old 24-01-2007, 16:19   #2
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Quote:
Originally Posted by Crak
I own a new Fountaine Pajot Athena 38 and while sailing close hauled or close reach the leeward shroud becomes very loose and flops about and will snap tight again with a shudder if the load suddenly comes off the sail. I was told this is normal by the guy who tuned up the rig and he suggested using a bungy cord to stop the shroud flopping around on long passages. Can any one out there give me advice if this is normal on a cat, or does it sound like my shrouds are too loose?

Regards,

Crak
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Mate this is fairly standard on cat's, and the rigger is correct with the bungy coard.

We used 10mm black from a chandlerie which you can get by the metre and tied it with a series of rolling hitches onto the shroud to stop it sliding down.

Double up on your size cat and tie about 4 ft up and take it back to something.

We only used a short length, and used VB cord or simmilar for the rest of the length

Have Fun

Dave

PS, and Welcome Aboard.
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Old 24-01-2007, 16:47   #3
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Thank you for the reply Dave.
It's nice to know every thing is fine and I will make some thing up like you suggested.

Crak
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Old 24-01-2007, 19:21   #4
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I would think if this were a common ocurrence that Cat builders would install slack tentioners like whats used in pulley systems. Or even what's on cargo ships that keeps wire lines taught while paying them in and out.

I've always gotten the impression that shrouds that go slack can be dangerous due to the sudden whip and stress as when a vessel crests a swell/wave. And the life span certainly would be shortened................._/)
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Old 24-01-2007, 20:02   #5
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Delmarrey,

That is exactly what I was thinking too, and the reason for posting the question.

Crak
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Old 25-01-2007, 02:00   #6
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An “extremely” loose leeward shroud will produce an inefficient sail shape, and might represent a serious risk to the standing rig and hull, due to the continual flexure of a “whipping” stay, and distorted mast.

The cause may be a too loosely tensioned rig, or an excessively flexible structure*.

* Not unheard of, in some catamarans, particularly those designed and/or built to Dennis Connor’s admonition: “If it does not break, its too heavy.”
I wouldn’t expect this phenomenon from properly tuned a Fountaine Pajot Athena.
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Old 25-01-2007, 09:50   #7
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I have a Manta 40 and when hard on the wind, the leeward shroud is less tensioned, but hardly loose or flopping. I won't/can't make recommendations on your rig, but I would recommend you get an opinion from the factory or at least another rigger familiar with this type of catamaran.

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Old 25-01-2007, 13:05   #8
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While sailing on the wind, check to see if the masthead is bending to leeward by sighting up the mast. If so then your shrouds are not adjusted correctly.

I suggest that you hire a rigger to teach you how to tune your rig. This should include making adjustment while under sail.

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Old 25-01-2007, 14:16   #9
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SOme slack in the leeward shroud is normal. The practice of using bungee cord to restrain it is fairly commonplace. Viking, on a cat the mast is held in column by the diamond stays, not the shrouds. The shrouds hold it up, not straight.
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Old 25-01-2007, 15:16   #10
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Quote:
Originally Posted by delmarrey
I would think if this were a common ocurrence that Cat builders would install slack tentioners )
We do, it's called Bungee cord

Dave
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Old 25-01-2007, 15:18   #11
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SOme slack in the leeward shroud is normal. The practice of using bungee cord to restrain it is fairly commonplace. Viking, on a cat the mast is held in column by the diamond stays, not the shrouds. The shrouds hold it up, not straight.
Exactly right 44CC

I've sailed on cat's with 28 ft beam's that have about 1 metre of slack on a large rottating mast.

Dave
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Old 25-01-2007, 16:38   #12
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Quote:
Originally Posted by Crak
I own a new Fountaine Pajot Athena 38 and while sailing close hauled or close reach the leeward shroud becomes very loose and flops about and will snap tight again with a shudder if the load suddenly comes off the sail. I was told this is normal by the guy who tuned up the rig and he suggested using a bungy cord to stop the shroud flopping around on long passages. Can any one out there give me advice if this is normal on a cat, or does it sound like my shrouds are too loose?
On my privilege 39, I have never had significant slackness in the leeward cap shroud on any point of sail. I have upper and lower diamond stays to keep the mast in column, and I have cap shrouds that keeps the mast in position.

I keep my cap shrouds tight, and I have never seen them moving around on the leeward side when sailing to windward. It makes we wonder if I have kept the cap shrouds too tight.

The Privilege 39 is a very robust hull and relatively small in size. Maybe there is less flexing in the hull than in some other catamarans, and perhaps that is why the leeward cap shroud doesn't go slack.

If I was sailing offshore and saw this type of looseness in the cap shrouds I would be very concerned. Nothing good can come shock loading of a backstay.

I am wondering if there is less slackness on my cat because I have a very stiff small hull, I have double diamonds stays, and I had tight cap shrouds.

In an eleven year circumnavigation, I replaced every piece of rigging on the boat except for the cap shrouds. Interesting. Only the tight cap shrouds survived.

Regardless of what riggers say, I will continue sailing with tight cap shrouds.

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Old 26-01-2007, 06:59   #13
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I did actually see a cat several years ago in NQ, whose owner tightened her shrouds on every tack In the NQ tropical heat.

This cat ended up with severe crinkling [creep] of the glass around the chainplates.

She also had issues with the compression post area.

Poor old girl.

Some people just don't deserve nice boat's.

Dave
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Old 26-01-2007, 07:49   #14
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I did actually see a cat several years ago in NQ, whose owner tightened her shrouds on every tack In the NQ tropical heat.

This cat ended up with severe crinkling [creep] of the glass around the chainplates.

She also had issues with the compression post area.

Poor old girl.

Some people just don't deserve nice boat's.

Dave
I have also seen cats with issues in the compression post area. Certainly if there were any stress cracks in the deck at the base of the mast, it would indicate that shrouds are too tight.

On my catamaran, I don't have a compression post per se, but the mast base sets on three separate bulkheads below the deck. There is a transverse bulkhead in the front of the salon, and then double bulkheads separating the two forward cabins. This seems like a fairly robust system that has stood up to the test in the past thirteen years without any problem.

I would like to have seen the catamaran with the fiberglass damage in the area of the chainplates in NQ. The heat in NQ certainly could be a factor, but you also wonder about the robustness of construction in that particular cat, and I wonder about the size of the chainplates as well.

The privilege 39 has massive chainlplates for the cap shrouds. I just walked down the dock and looked at the chainplates on a Mahe 36, and our chainplates are twice the size. In addition, we have seven large bolts holding the chainplates in place.

Every catamaran is different. They are engineered to different levels and the quality of construction varies widely. Some yachts are very robust and heavy like a privilege 39. We aren't a greyhoud, that's for sure. But we are rock solid.

Tight shrouds aren't a problem on our yacht. But some go fast boats with lighter engineering probably shouldn't have shrouds that are so tight. I don't think that slack shrouds are a problem as long as there isn't any repetitive shock loading on the rig.

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Old 26-01-2007, 19:19   #15
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Originally Posted by colemj
I would recommend you get an opinion from the factory ....

Mark
Probably the best advice so far.
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