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Old 22-11-2013, 15:06   #31
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Re: Screecher ?

I would probably follow Selden's recomendation, but wouldn't cut it unless I had too. If I remember correctly the Selden unit has a base for where the inboard end attaches, and I would just relocate it to goes proper length. This way you could modify it later if you want to.

I don't know if you have bought the continuious furler yet, but the Karver's are the best I have ever used, but very expensive. Fancor is probably the biggest seller, and are good. I really like the Colligio one, and John is a pleasure to work with.
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Old 22-11-2013, 16:01   #32
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Re: Screecher ?

The one we have is some 55cm plus it's conicale attachment which does
not make it stand away further then 65 cm from the front beam !!
Remember you have to be able to bring it in, hangin over the beam doing that
,,, besides sticking it out further has what advantage,,,
Also in difficult moorings even the 65 cm are in the way and not very
solid on the front beam and hull attachments,,
the original FP comes all the way from the cabin for,,,,
reinforcement!
sorry i would keep it short!
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Old 22-11-2013, 16:51   #33
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Re: Screecher ?

Thanks all good points, Seldon is now saying longer the better for performance because it increases the size of the sail as well as getting it out into clearer air.
That is fine but there engineering issues as well as boat handling which you guys have mentioned.
Hmmm.
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Old 22-11-2013, 17:48   #34
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Originally Posted by Dragon Lady View Post
Thanks all good points, Seldon is now saying longer the better for performance because it increases the size of the sail as well as getting it out into clearer air.
That is fine but there engineering issues as well as boat handling which you guys have mentioned.
Hmmm.
If you want to run deep then the longer the better. some of the yachts i race on are out to 4m. but come up onto a beam reach and you get lee helm. so the length is related to the sail type and what angle you are going to sail. for a screecher 1m. for a all purpose gennaker 2m etc.
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Old 23-11-2013, 09:56   #35
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Re: Screecher ?

Yes I'm going to talk to my sail maker next week, perhaps two mounting points are the go. One for the screecher and another for a kite, but I'm not sure how that will go from a structural point of view.
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Old 23-11-2013, 21:18   #36
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Yes I'm going to talk to my sail maker next week, perhaps two mounting points are the go. One for the screecher and another for a kite, but I'm not sure how that will go from a structural point of view.
probably not good. i would just keep it 1.5m if the attachments are strong enough.
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Old 26-11-2013, 03:20   #37
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Re: Screecher ?

The 1 metre length is looking like the way to go as I can only reach that far from the cross beam. The sail maker agrees and says it will be better for the code zero set up.
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Old 26-11-2013, 14:08   #38
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Re: Screecher ?

Are you planning on adding a bobstay? For code sails they are typically required to put the pole in compression.
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Old 26-11-2013, 15:23   #39
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Re: Screecher ?

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Are you planning on adding a bobstay? For code sails they are typically required to put the pole in compression.
Thanks, you are the second person to mention this however no one can tell me why this is so.
Drawing vector diagrams seems to indicate that the loads are not that high.
Considering that the cross beam is happily taking the load of the Genoa I think it should be OK.
But if someone can give me evidence of why I need one I would appreciate it.
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Old 26-11-2013, 16:45   #40
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Re: Screecher ?

Code zeros are like oversized jibs and require a lot of halyard tension to fly properly. All this halyard tension has to be constrained by the pole and it's fittings. On a cat there are two places to mount the pole above deck, and below the deck, each have their own issues.

Below the deck the outboard end is lifting up, hinging on the deck itself, and the inboard end is trying to rip itself out and down. Above the deck the outboard end is lifting up, the middle bracket is pulling down, and the inboard end is pushing down into the deck.

The longer the pole the longer the leaver arm, and the more torque it generates (this is one reason the retrofit poles are so short). The contain the vertical load of a code zero you can either go with a very stiff pole and very strong fittings, OR add a small stay that adds a vertical constraining force. This puts the pole in compression instead of lifting, and aluminium is much stronger in compression than it is stiff.
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Old 26-11-2013, 19:08   #41
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Re: Screecher ?

Sorry I missunderstood what a bob stay is. Yes I will be running stays from the end of the pole down to each hull.
It is a compression post going from the cross beam back to the bridgedeck that I'm not sold on.
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Old 26-11-2013, 19:44   #42
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Re: Screecher ?

Ahh,

I haven't run the calculations on this, but I have seen a few units with code sails and no backing brace. With a sturdy enough deck fitting I wouldn't be too concerned about it. I might add it anyway if there was an easy way to install it, but otherwise I wouldn't be too worried.
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Old 26-11-2013, 19:55   #43
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Re: Screecher ?

Yeah thanks for that, I am thinking I will keep an eye on the cross beam to see if there is any deflection. The beauty of alloy is tends to move a bit before it breaks or bends permenantly.
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Old 26-11-2013, 20:36   #44
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Re: Screecher ?

Hmmm,

I did some research into the Lavezzi and I have some doubts about just mounting a pole to the crossbar. I don't know that you could get enough torsional stability to control the twist. You may want to contact the manufacturer and get some direction. I could easily see using a long pole running front he bridgedeck under the crossbar and projecting out.
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Old 27-11-2013, 17:17   #45
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Re: Screecher ?

OK, I've hit a bit of a glitch with my pole kit.
It seems the tube is only strong enough for down wind work so the screecher or code zero is out with this pole at least.
If I want a screecher I will have to build something myself.
As all I wanted was some downwind performance with easy handeling I'm talking to the sailmaker about an asyso kite with a sock.
I could go for a top down furler but seeing the issues that my mate, the Seldon guy, is having with his one and the extra cost I think the sock is the way to go.
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