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Boom Vang Measurements & Fittings

Postby A Trace of Blue - 1666 on Fri Dec 02, 2005 1:54 am

My turn to try to start a lively discussion - and Phil J will probably tell me off next time I ring him hehehehe

Technically, as I understand it, under the existing rules only 1 'style' of fitting is currently legal for use in connecting the Vang to the Boom on a Sabre. Problem - Ronstan don't make them any more, and the imported alternatives are not always easy to get and are expensive.

On a past Sabre, sailed by my wife, and not realising the rigidity of the rules, we initially fitted a T-Ball fitting for the Vang to connect to the Boom. The T-ball fitting is a cheaper, simple, quick to connect, and reliable way of doing it.

To our dismay, it was when we had the boat measured, we found out the T-ball was not legal, as the front of the T-ball keyhole plate fitting was internal to the boom and could not be measured. We were not exactly happy, but - The Rules are the Rules, so we changed it and complied with the Rules.

Later that year, at the Brighton Nats, a boat was seen with a Saddle fitted internal to the boom, but the U of the saddle sticking down through and out of the boom for connecting the Vang to it - Can someone please tell me where this is different?

Now people are, it seems, starting to use webbing straps over their booms to connect the Vang to it. - Can someone please explain to me how a non-rigid piece of webbing can be measured as being legal for use at a State or National level under the existing rules, when the first two alternative methods were not legal? It would only take someone to be a bit of a pain, and protest all boats using webbing Vangs at this level to cause mayhem within the class, and upset the people rigged that way.

I know Phil is having head aches over this one.

It seems We as a class have to get off our butts and get something sorted out here, and sooner rather than later. We should not be just waiting and leaving it up to the Comittee to get sick of people asking the same question until they make a decision for the sake of making a decision.

If there is a problem we need to generate some discussion to assist this process and get a possitive outcome for the class. We who own/sail the Sabres All own the Class.

Back to the Vang. The Sabre is as popular as it is because apart from being fun to sail, they are without doubt one of the cheapest boats in the country to own and maintain. You can also build your own from scratch rather than have to go to a single specified builder to buy one.

Why do we then stay with a stupidly expensive and difficult to get fitting for the Vang when other simpler and far cheaper methods are available and just as or more effective.

My wife's Heron (She has boats, not just a boat) uses an identical T-ball fitting for its Vang, and has done for 5 years. There has never been any problem or hint of failure of the boom section at the Vang connection point. The Heron Boom is the same 50mm ally section as used for the Sabre boom, and the Heron Vang is 16-1 not 4-1 so it sees a lot more load than a Sabre should ever.

I have a webbing strap set up on my other boat, A Payne-Mortlock Sailing Canoe (rigged similar to a LW Sharpie for anyone not knowing the class), and I have bent two booms at the point where the webbing is fixed to the top centre of the boom. I still use that system but have a stronger boom section now. I am doubtfull that webbing is a good way to go on the Sabre, but reccomend if LEGALY adopted, fixing be required at the sides of the Boom, not top centre.

Can we please have some discuss on the best way ahead to resolve this issue that will hopefully not disadvantage anyone, and remains fair to the class.

I have a couple of Ideas, and have forwarded them to Phil J.

Basically I support change for the Vang Rules:

1. Webbing: Set a fixed length/width/looping method for the webbing and decide how to measure its position (Possibly angle of the line of the Vang, from the Mast to the boom, with the Boom set at a right angle to the mast), and

2. T-Balls should be legalised, with the front edge of the hole in the keyhole fitting (where the load bearing point is when T-ball is inserted) is set as the measurement point. (A saddle or even a block hanger could be leagalised)

3. Allowing up to 8-1 Vang by the addition of a single waterfall arrangement to the existing 4-1 system.

Regards . . .

Willy . . .
Peter Wilcox
1666 - A Trace of Blue

God Still Sails a Payne-Mortlock Sailing Canoe!
A Trace of Blue - 1666
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Postby John on Mon Dec 11, 2006 10:25 am

The intention of the recent rule amendmants proposed by the Victorian committee was to remove the restriction on fittings used and to remove the vang measurement point on the boom. The removal of the restriction on fittings was passed but unfortunately the removal of the measurement of the attachment point on the boom was not. This means that there is some confusion about what point is measured if alternative attaching methods are use. We will be proposing another change to either remove the measurement point or to define it so that any attachment method can be used without risk of it failing to comply with rules.
John Dixon
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Postby andrewb on Tue Dec 12, 2006 9:31 am

What about making the vang rule a maximum measurement from the aft face of the mast to a point on the top edge of the boom? The vang and all boom attachments (or an extension of the line of the vang), when rigged as for sailing, must intersect the top edge of the boom forward of this point. This would cover any type of attachment.
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Postby GuestMember on Sun May 06, 2007 1:15 pm

I reckon Andrew's suggestion is a good one. It would tidy up an uncertainty that currently exists.
What I don't get is why it is taking so long to get the rule clarified.

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Agree - keep it simple

Postby Slow Hand on Mon May 07, 2007 2:00 pm

I concur Matt,

Here is a link to the Spiral class drawings for measuring boom vang attachment. Measurements are based on extrapolating the bearing point to the centre of the spar, and having a max and min distance back from the aft edge of the mast.

http://www.spiralsailing.org/The%20Ding ... awings.pdf


PS I hope I don't get into trouple for using the S***** word.
Slow Hand
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Postby Chriso on Tue May 08, 2007 1:42 pm

So the current situation seems to be that we don't have to use a fitting that is no longer made but we do have to comply with the class rule which does not exist.

Please correct me if I am wrong....

Sabre 1335
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Postby GuestMember on Tue May 08, 2007 11:09 pm

Hi Sue
The Spiral (there I've said it) seems like a good solution. All it needs is a dinky little diagram and a measurement and away we go all happy.

I'm new to the class and maybe I'm missing something, but it seems like an eternity to get this rule clarified.

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Postby andrewb on Wed Jan 09, 2008 9:31 am

Just to revisit this topic. I am in the process of fitting out a new boom & need to clarify the current rule regarding the position of the Vang fitting on the boom. The rules state:

b. The vang boom fitting is measured from the innermost edge of the fitting to the aft
extremity of the mast when boom is fixed onto the mast gooseneck.

This appears to allow a fair degree of latitude in the actual bearing surface / attachment point for the vang, depending on the the exact fitting used. The fitting I am using (off an old - measured - boom) has the bearing surface 11 mm from the front edge of the fitting. With that distance I cannot position it so that both the front edge and the bearing surface are within the measurement tolerance so I wish to be absolutely sure which point it is that the measurement is taken from.
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Postby Mike Simpson on Wed Jan 09, 2008 12:04 pm

The recently adopted revision to the measurment rules specify:

"The forward extremity of the vang boom fitting must be between 665 & 690 mm measured from the innermost point of the fitting to the after face of the mast with the boom fitted to the mast gooseneck, the sail rigged and the vang tensioned."

This is a small change to the aftermost limit to allow for a bit of stretch in strap type hangers.

It is definately intended that the measurement be made to the most forward point of the attachment fitting and has no reference to the actual hole to which the tackle is attached.
Mike Simpson
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