Pull vangs (various) is boom reinforcing required?

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EdS
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Pull vangs (various) is boom reinforcing required?

Post by EdS » Sun Mar 03, 2013 6:04 am

I noticed in LA that the boats with a boom other than box section that had any kind of pull down vang variant had a thick carbon plate lamInated inside the boom in the verticle plane extending back to the loaded area.

I dont understand the reason for the reinforcement.

what am I missing?
Roaring Forties GBR1524

Dan H
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Re: Pull vangs (various) is boom reinforcing required?

Post by Dan H » Mon Mar 11, 2013 9:22 am

Its a shear web - think those round booms are actually spinnkaker poles - the large diameter/thin wall would be prone to crushing either when it pokes out of the bow, or at the vang point, so a bulkhead was necessary. Apparently.

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Shu
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Re: Pull vangs (various) is boom reinforcing required?

Post by Shu » Mon Mar 11, 2013 6:01 pm

Dan's right. The section is quite large with a thin wall, so point loading from the vang could be a problem. The spinnaker poles however, don't have the reinforcing web. But they are supported by the quite stiff bow sprit/pole sleeve.
Steve Shumaker
USA 1183

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rand
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Re: Pull vangs (various) is boom reinforcing required?

Post by rand » Mon Mar 11, 2013 6:34 pm

I have to chime in and say that it has to do with what materials are used to build the boom.

My two year old boom from Kris Henderson, does not have this vertical plate inside. It does bend, but seems to be holding up fine with a traditional vang and mid boom sheeting.
Rand Arnold
International 14 USA 1143
"A Bumblebee Called Kate"
(former US President, former US Measurer)

EdS
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Re: Pull vangs (various) is boom reinforcing required?

Post by EdS » Tue Mar 12, 2013 4:04 pm

Thanks chaps,

Thought it might be to do with using poles as booms.
Roaring Forties GBR1524

Hendo
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Re: Pull vangs (various) is boom reinforcing required?

Post by Hendo » Wed Mar 13, 2013 4:44 am

Ed,
When Paul first developed the Bieker spars. at that time setting up the tooling it was easier to make an Alloy tool for the pole that worked for the boom as well..
Note that Paul has never been paid for any of this, and tooling is not cheep. Of course none of us were using as much vang back then and that is why some have felt that a web in the spar would help. The tube is designed different on the pole , where there is a rap of reinforcement right were it comes out of the tube on the hull. On the boom the reinforcement is at the vang area. Since the Long Beach worlds, we have looked at this a little closer and have added a whole extra layer of carbon over the full tube. If you call Ryan at I.C.E. this is known as "the extra heavy boom" meaning a thicker wall. This is what Rand is sailing with. And So, like and tapered tube, yes it bends a little. Paul has told me (Shu ) , that a little bend is ok.

EdS
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Re: Pull vangs (various) is boom reinforcing required?

Post by EdS » Fri Mar 15, 2013 2:20 pm

Hendo,

Thanks for the info. The reason for asking the question is because i have an oval cst boom which may have a traditional kicker fitted soon, depending if i change masts.

After looking round boats in San Diego and Long Beach wanted to ask the question about whether the reinforcement was specific to this boom or is it sensible for stiffening all booms or did it have something to do with the different loading applied from a strop (collapse and small contact area) rather than a slider on a GNAV(bending stress and large contact patch)

Anyway question answered, thanks for the input.
Roaring Forties GBR1524

Hendo
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Re: Pull vangs (various) is boom reinforcing required?

Post by Hendo » Sat Mar 16, 2013 6:36 am

Ed., I like how you think. the Gnav is the way to go but, the sail makers and the pro's (some),don't like the way the mainsail is set.
Note the bit around the Gnav ,but what it is doing to the midleach.
Archey seam's to make it work.

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Re: Pull vangs (various) is boom reinforcing required?

Post by Hendo » Sat Mar 16, 2013 6:39 am

Fallow more Q''s and answers on the .. New B6 page.

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