Boom Vangs

Discuss the IOM class rules and interpretations

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Lester
Posts: 611
Joined: 14 Oct 2004, 22:29
Location: GBR 105
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Post by Lester » 21 Apr 2007, 19:12

Hi Barry

A boom vang or kicking strap is defined to be an item of rigging by the class rules:
F.6 RUNNING RIGGING
F.6.2 CONSTRUCTION
(a) MANDATORY
(2) Mainsail boom kicking strap
Then, in the ERS (equipment rules of sailing), we see that rigging is something that works in tension only (not compression):
F.1.4 Rigging
Any equipment attached at one or both ends to spars, sails or other rigging and capable of working in tension only.
So that's why the IOM vang cannot hold the boom up...
Lester Gilbert
http://www.onemetre.net/

Hiljoball
Posts: 270
Joined: 06 Jan 2006, 00:47
Sail number: CAN 307
Design: V8
Location: CAN

Post by Hiljoball » 22 Apr 2007, 01:37

The kickingstrap occurs in two places in the rule. In addition to F6 where it is part of the running rigging, (and must operate in tension per ERS), it also occurs in
F.4.3 MAINSAIL BOOM FITTINGS
(a) MANDATORY
(3) Kicking strap fitting.

In this setting, there is no requirement to operate in tension.

This sounds like a case where the duplication should be removed from the rules. If we remove it from F6 then the tension issue goes away.

When I look at kickingstraps that feature a solid rod with a screw adjuster, that looks to me like it could also operate in compression (support the boom) and that sounds contrary to the requirements of ERS.

My sense is that the kicking strap is NOT part of the running rigging, but is part of the boom hardware, and the reference in F6 should be removed at the next opportunity.
John Ball
CRYA #895
IOM CAN 307 V8
In my private capacity

Andy Stevenson
GBR NCA Officer
Posts: 772
Joined: 15 Sep 2005, 13:08
Location: UK

Post by Andy Stevenson » 22 Apr 2007, 09:01

Hi John,

I’ve had the kicking strap conversation before, within the World Council, so have looked at this fairly closely.

The Class Rules define a kicking strap CR F.6.2(2) and two kicking strap fittings, one on the mast CR F.3.3(4), one on the mainsail boom CR F.4.3(3).

The fittings are defined as fittings and so unrestricted in how they operate. The kicking strap itself is defined as rigging and so must comply with the ERS definition, hence only work in tension.
My sense is that the kicking strap is NOT part of the running rigging, but is part of the boom hardware, and the reference in F6 should be removed at the next opportunity.
I disagree; I think the kicking strap comprises 3 distinct parts: one mast fitting, one boom fitting and rigging joining the two. I think this is correctly defined in the CR.

cheers
Andy Stevenson
"A little pain never hurt anyone!" Sam, aged 11

Hiljoball
Posts: 270
Joined: 06 Jan 2006, 00:47
Sail number: CAN 307
Design: V8
Location: CAN

Post by Hiljoball » 22 Apr 2007, 17:01

Thanks Andy. I did not pick up on the word 'fitting' in the phrase kicking strap fitting.
John Ball
CRYA #895
IOM CAN 307 V8
In my private capacity

Barry Fox CAN262
Posts: 354
Joined: 21 Apr 2007, 17:54
Sail number: CAN 46
Club: VMSS
Design: V8
Location: Vancouver Island, BC, Canada

Post by Barry Fox CAN262 » 22 Apr 2007, 22:43

Thanks for all the answers. I would have responded earlier but I had a bit of User ID trouble and couldn't get back in since I posted the original question.

The answer is pretty clear now. I wasn't looking for a performance advantage but just a simple, inexpensive, accurate piece of equipment. I'll put on my thinking cap and come up with an alternative.

Having only been at this sailing stuff for a couple of years, these kinds of discussions, which are very good, make me believe that I'm not the only person who has difficulty picking up the references sometimes.

I am aware of the issues around "hard-wiring" references to other rules sources into your own rules but I think doing so would cut down on interpretations and speculation.

Back to the drawing board.

Thanks again for all the well thought out answers.
Barry Fox
CAN 46
Vancouver Island, BC, Canada

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