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Jib Attachment

Posted: 10 Feb 2009, 07:18
by RoyL
I have always believed that the class rule interpretation that changed the practice of having to attach the jib to the deck because the then technical committee could not define "the deck" of an IOM to be wrongly decided.

I think the "deck" is rather obvious on almost all boats, and in all events the attachment point could at worst mean the solid deck plus or minus an inch or so to deal with recessed or raised decks. One thing I am certain of is that the "deck" is not the bottom of the hull.

Without banning and grandfathering all current boats, is there any desire to revisit this issue?

Posted: 10 Feb 2009, 13:40
by Olivier Cohen
I am sorry, maybe I don't understand english as well as I would like, but do you mean that the solution applied on hundreds of IOM, a line attached at the bottom of the hull, is not a good solution, and should be forbidden in the rules?

My opinion is that such a solution is far more cheaper and functionnal than a solution were you have to add a ball bearing between jib boom and attachment.

So IMHO interpretation 2004-IOM-2 ( ... -IOM-2.pdf) is a "good" one!

Posted: 10 Feb 2009, 14:36
by Alfonso
I am also sorry Roy because I do not understand where is the problem. I think I miss something. Can you give us a more detailed explanation?

Posted: 10 Feb 2009, 16:23
by RoyL
A little bit of history---the original IOM rule required essentially that the jib be attached by a hook to the "deck". At some point in time, someone raised the argument that there was no way to accurately define a "deck" and that accordingly jibs should be allowed to be attached through the bottom of the boat. The then existing technical committee agreed and the rule was effectively eliminated by technical interpretation rather than by vote of the class.

It has always appeared to me that this was flat out wrong. I might not know many things, but I am pretty certain that a hole in the bottom of the boat is not the "deck" and that if someone wanted the rule changed it should have been proposed and voted upon.

Since that rule interpretation a number of boats have used the string through the bottom of the hull system. I am not suggesting making any of those boats illegal. However, what I would like is for the IOM Class to have its "decks" back and the rule either rewritten and voted upon to allow attachment through the bottom of the hull or going forward we go back to the rule as written where jibs are attached via a hook/swivel on the deck. I personally have no opinion either way, except I think we should be honest and accurate in our rules and fix a prior "interpretive" mistake.

Oh, and the cost of a jib swivel is also essentially nothing. On most of my boats I use a string and a bent metal hook.

Posted: 10 Feb 2009, 21:27
by Lester
Hi IOM sailors.

It may be worth providing a history which is accurate in regard to the dates, processes, and organisations involved.

In 2002, RSD issued the 2002 CRs. In there we could read:
(a) Use
The headsail boom swivel shall be attached to the deck approximately on the hull centreplane. The alignment of the swivel shall be controlled only by the rigging tension.
Following the appearance of the SAILSetc jib swivel, the AMYA requested an interpretation:
Interpretation 2003-IOM-1 wrote: Interpretation requested by the AMYA, USA, as follows:
Is it permitted to use headsail swivel made of a cord attached inside the watertight tube connecting bottom of the hull and deck and passing through the tube up to the deck level where it is attached to the headsail boom?
A headsail swivel attached at any height inside a tube which is connected to the deck approximately on the hull centreplane is in compliance with class rule C.7.6(a).
Robert Grubiša, ISAF-RSD Technical Committee Chairman
The outcome of the request was that the swivel in a tube attached to the bottom of the hull was judged to be legal.

In 2003 the RSD issued the 2003 class rules. Amongst a number of tidying ups, the RSD incorporated the effect of interpretation 2003-IOM-1:
The headsail boom swivel shall be attached to the hull approximately on the hull centreplane. The alignment of the swivel between the hull and the headsail boom shall be controlled only by the rigging tension.

Posted: 10 Feb 2009, 23:06
by Olivier Cohen
RoyL wrote: Oh, and the cost of a jib swivel is also essentially nothing. On most of my boats I use a string and a bent metal hook.
Certainly, I've got the same for B and C rigs, but for A rig with light wind, if you want a jib boom as low as possible, that system doesn't work.

Posted: 10 Feb 2009, 23:21
by Robert Grubisa
It is not so easy to define the "deck shape" on the IOM class boats as "Development class with some One Design characteristics and with absolute limits to hull length, hull depth, displacement and draft and with One Design rigs." (extract from IYRU MYRD Policy for Classes and Intent of the Class Rules) -

RSD TC used the document as guideline when making interpretation on class rules. Early IOM had flat decks (with uniform moderate sheer and camber) with string and hook as jib swivel. One of the first "unusual" deck type on IOM class boats was "skiff deck" on famous TS-2 boats. I do not think that original rule maker had such a type of deck on their mind and prohibition of such type of the decks was one of option.

TC obviously decide at that time that such type of deck is good for class and in accordance with the intent of the class rule i.e. "with the idea of development class with some One Design characteristics...) I think that such action of the IYRU MYRD (later ISAF RSD) TC allow us to have such beautiful IOM designs such as TS-2, Ikon/Italiko/Topiko/Pikanto, Disco, Ocka/Mirage and many others....

Decks forming recesses/tubes for swivel attachments, lowering of deck in aft part, lowering of deck around the mast, recesses for masts stepped at the boat bottom, etc are now common on IOM class and many designers/builders are using them. I do not see the problem with current wording of the IOM class rules and mentioned features if we agree that the shape of the deck surface on the IOM boats is unrestricted.

If IOM ICA want to restrict the shape of the deck than appropriate class rule(s) which will describe the shape of the deck must be added to the IOM Class Rule.

Posted: 11 Feb 2009, 04:54
by RoyL
Robert--Nothing I saw in the "old rule" limited the shape of decks. The point was should the jib be attached to the "deck" (something pretty obvious to just about anyone) or the bottom of the boat. I believe the tech committee should never have changed this rule by "interpretation", right or wrong it should have been voted on.

Posted: 11 Feb 2009, 10:30
by valpro
ERS D.1.1. defines the hull shell as including 'the deck and any superstructure..' so while I take Roy's point that the class rule does not define the 'deck' (and in my opinion it should not even try to) the matter of where the actual attachment of the jib is is clear enough. Since the deck is an integral part of the hull shell I am quite happy with the physical attachment of the jib to the bottom of the tube that, you can convincingly argue, is part of the structure of the deck.

Posted: 11 Feb 2009, 10:52
by Robert Grubisa
valpro wrote:Since the deck is an integral part of the hull shell I am quite happy with the physical attachment of the jib to the bottom of the tube that, you can convincingly argue, is part of the structure of the deck.
I agree with Val. In addition, note that normally the lower end of jib swivel cord is attached to the metal pin glued to the lower part of the tube (as part of the deck) not on hull shell itself.

Posted: 12 Feb 2009, 07:35
by RoyL
Maybe I'm making too much of this, but I have to disagree. If you read the rule originally it did not allow the jib to attached via a string to the bottom of the boat, the jib was supposed to be attached to the "deck". I don't think expanding the plain and simple meaning of deck to permit the practice of attaching the jib through the bottom of the boat was proper. It should have been put to a vote of the class, not rewritten by the technical committee.

Posted: 12 Feb 2009, 08:14
by Lester
RoyL wrote:It should have been put to a vote of the class
From the actual description of events, the class asociation did not exist at the time the 2003 rules were finalised. The interpretation arose as a result of a request for such an interpretation from the AMYA. There was no submission of a desired rule change following the interpretation.
... rewritten by the technical committee
The RSD Technical Committee did not re-write the rule. The RSD (RSD TC recommendadtions have to go to the RSD PC for approval) simply gave effect to a standing interpretation.

[Edit to spelling and quote]

Posted: 12 Feb 2009, 11:57
by valpro
As a member of RSD-TC since 2002 I can confirm that. as there was no existing Association and therefore no mechanism to allow consultation with the members, the matter was, quite correctly, referred to the Tecnical committee for an interpretation. After some deliberation, we came up with one.
What we are seeing here is the result of trying to tie down, in absolute terms, what is and is not allowed under the rules. And I can assure you from long experience, the more you try to tie it down, the more trouble you create. I cant say I like the tube system particularly but unless there is some freedom to experiment and develop ideas in these boats, they will become less interesting and people will drift into other classes. We have a box rule for the hull and a 'One Design' rig and it all doesn't seem to me to be broke so it dont need fixing in my eyes at least.

Posted: 12 Feb 2009, 18:37
by Barry Chisam
To look at it another way the tube is purely a deck recess which is bonded to the hull at its base, same as the rest of the deck is bonded to the hull.

Thanks Val for keeping sanity alive.

Posted: 12 Feb 2009, 20:13
by valpro
Just like the mainsheet post socket and remember the arguments we had about that!............