Mat'ls: keel & rudder; mast, boom, stand. rig. fittings

Discuss the IOM class rules and interpretations

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cfwahl
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Mat'ls: keel & rudder; mast, boom, stand. rig. fittings

Post by cfwahl » 03 Apr 2005, 01:27

E.3.1 stipulates that "Materials shall not be of density higher than lead" but it does not specify what materials are permitted. [If "Materials" for keel and rudder are covered by the "Construction" (unrestricted, per E.3.2), then what is the difference between Materials and Construction, that they are contained in different numbered sections?]

Sections F.3 (Mast) and F.4 (Booms) define permissible materials and construction for spars, but not for fittings; yet the latter are not explicitly unrestricted. What materials and construction are permitted for mast and boom fittings [some of which are mandatory!]?

Section F.5 (Standing Rigging) excepts termination and headsail boom swivel from the restriction to steel and/or polymer; but it does not permit any materials explicitly. [If those excepted items are unrestricted, shouldn't the rule say so?]

If I've missed something, it wouldn't be the first time. If not, then I will submit to my NCA for interpretation.
Charles Wahl

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Re: Mat'ls: keel & rudder; mast, boom, stand. rig. fitti

Post by Chairman » 03 Apr 2005, 18:48

cfwahl wrote:...what is the difference between Materials and Construction, that they are contained in different numbered sections?
Hi Charles

Even though there is some natural overlap between these concepts, I guess we can agree that these two headings are not used with total consistency in the rules.
Sections F.3 (Mast) and F.4 (Booms) define permissible materials and construction for spars, but not for fittings; yet the latter are not explicitly unrestricted. What materials and construction are permitted for mast and boom fittings [some of which are mandatory!]?
Good question!
Section F.5 (Standing Rigging) excepts termination and headsail boom swivel from the restriction to steel and/or polymer; but it does not permit any materials explicitly. [If those excepted items are unrestricted, shouldn't the rule say so?]
Another good question! Both of these points show the difficulty of writing "perfect" rules. It can't be done, of course, but perhaps the next iteration of the rules could include an explicit phrase which indicates the restrictions on fittings, if any.
If I've missed something, it wouldn't be the first time. If not, then I will submit to my NCA for interpretation.
I appreciate your concerns here, and am confident they will be taken on board. On the question on requesting a formal interpretation, it would be best for such a request to be specific on a practical question that needs an answer, rather than dealing with some generality or some issue "in principle". Is there a specific fitting whose legality you are doubtful about?
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cfwahl
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Post by cfwahl » 03 Apr 2005, 23:29

Hi Lester, thanks for the reply.

I'm [s l o w l y] building an own-design boat, and rather than use all the commercially available (read SailsEtc) fittings and other stuff, I'm making most of them myself --it's a hobby, eh? So when I go to the rules (which I believe I am slowly learning to parse better), I find little pockets of vacuum. What's a compulsive I-dotter and T-crosser to do? So here I am.

In a purely practical sense, I can probably make things that nobody is likely to object to: stick to the usual sort of metals and polymer. On the other hand, I feel that the rules should not require me to guess. Where these vacui exist, technically no boat is in compliance; why should Bantock's fittings pass muster and mine not, just because someone has never seen mine? They're what I can make easily at home, and not intended to create some technical advantage that nobody else has.

See my previous post on adhesive attachment of fittings; there I'm at a loss. I don't see how adhering fittings to a boom section permanently would give me a competitive advantage, and it would be convenient. But the rules appear to be mute on the subject of attachment of fittings (or, indeed, on what constitutes a fitting).
Charles Wahl

spaldi01
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Post by spaldi01 » 04 Apr 2005, 10:09

Hi Charles

You have given me some concerns. As I understood the rules it is legal to permanently adhere fittings to spars. I have already done this on one of my boats! I am also building some new rigs where it was my intention to fix some fittings on the booms using epoxy and carbon fibre tow. I understand this to be legal as long as the fitting is not excessively large so that it stiffens the spars. Some clarification would be very useful.


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Post by Chairman » 04 Apr 2005, 12:31

I think (entirely unofficially, of course!) that fittings are generally unrestricted with regards to materials, construction, and fastening and/or attachment, except where a particular section of the rules might have something more definite to say. So it seems that the next revision of the class rules could do with some words which say something like:
In section E, Hull appendages:

E.3.3 FITTINGS
(a) Except as may be restricted elsewhere in section E, fittings are unrestricted with regards to construction, and fastening and/or attachment.
(b) Materials shall not be of density higher than lead (11.300 kg/m3).

In section F, Rig:

F.2.5 FITTINGS
(a) Except as may be restricted elsewhere in section F, fittings are unrestricted with regards to materials, construction, and fastening and/or attachment.
(b) A fitting attached to a spar shall be no bigger than is reasonably required for its purpose.

In section G, Sails:

G.2.6 FITTINGS
Except as may be restricted elsewhere in section G, fittings are unrestricted with regards to materials, construction, and fastening and/or attachment.
The "new" item here is F.2.5(b), borrowed from the Marblehead rules. Constructive comments welcome!
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cfwahl
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Post by cfwahl » 06 Apr 2005, 04:48

Chairman wrote: (b) A fitting attached to a spar shall be no bigger than is reasonably required for its purpose.
With sincere respect: the passage from the current IOM rule that I find most troubling is at F.2.3: "The function of items shall be limited to what is normally provided by items of their type." Is this adequate guidance for officials, who are presumed, like our Justice Potter Stewart, to know pornography when they see it, without the need for a definition thereof? Despite the difficulty of casting and maintaining a "prohibited unless permitted" rule set, I think that it's unfair to make vague limitations; I think they create more problems than they solve. If function is limited, then I think it's preferable to spell out clearly the acceptable functions of various items.

If there's going to be a limitation on size, why not make it absolute?: a fitting, including all parts involved in its function, fit into a box having interior x by y by z mm (articulated or flexible elements may be retracted as necessary). Sure, it's hard to determine what those dimensions should be, but it's much more objective, and less prone to spawn disputes about compliance.
Charles Wahl

edmorales

Post by edmorales » 06 Apr 2005, 09:49

speaking of fittings, the following photos shows a setup with an adjustable shroud/hounds attachment point. would this setup pass scrutiny?

http://www.rc-network.de/upload_02/foru ... 770021.jpg
http://www.rc-network.de/upload_02/foru ... 770055.jpg
http://www.rc-network.de/upload_02/foru ... 770078.jpg

ed

Jamestj
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Post by Jamestj » 16 Apr 2005, 18:22

The keel will not be able to be made of pure lead 'cos its too soft so it is alloyed. The alloy usually has a lower density. Other metals (and some non-metals) have a higher density so they could used instead eg osmium has a density of 22610 kg per metre cubed, lead is relatively light at a mere 11340 kg per metre cubed. If you made the keel out of osmium it could be half the volume and have lower drag. You'd have to be very rich, though since it would cost £millions to make a keel using osmium. Tungsten is much cheaper and a keel would cost about £50 in materials but you couldn't melt it with a camping stove like lead. It has a density of 19250 kg per metre cubed and would not damage the environment like lead if the bulb fell off.

Archaemedes principle could be used to find out if anyone was cheating by using too much tungsten in the keel and you wouldn't need to cut the keel in half to find out.

Has anyone used tungsten yet?

Jamestj
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Post by Jamestj » 16 Apr 2005, 18:34

I have an ingot made from an alloy of lithium and aluminium. They say that this material is stronger than steel and lighter than aluminium. You can't weld it since it burns but it seems O.K. to machine. Its not that expensive for IOM use since you would only use a little for fittings. It would be great for the hounds and the crane where weight aloft would be a nuisance. Just thought that I would mention it since the cost of the material would be insignificant compared with the cost of the machining.

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Post by awallin » 17 Apr 2005, 08:32

Jamestj wrote: Has anyone used tungsten yet?
IOM Class Rules wrote: E.3 KEEL AND RUDDER
E.3.1 MATERIALS
Materials shall not be of density higher than lead (11.300 kg/m3).
so it's not possible to use anything heavier than lead. your point about the environmental effect is more interesting.

I work a little bit with electronics in my dayjob and there is an EU or worldwide ruling to prohibit lead from solder within a few years. everyone is working hard to come up with alternatives...

anyone into hunting here ? have they prohibited lead from shotgun bullets ? (I faintly rememer something like this...)

lead in model yach keels might fall under a similar law in the near future ??
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ptercinet
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Post by ptercinet » 17 Apr 2005, 09:17

Unfortunately there is a strong lobying against the modification of the regulation concerning the bullets....

If I realise a mix of resin and
something with higher density than lead but with effective density < 11.3
is it legal ?

Pierre
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cfwahl
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Post by cfwahl » 17 Apr 2005, 15:58

ptercinet wrote:If I realise a mix of resin and
something with higher density than lead but with effective density < 11.3
is it legal ?
Read section E of the IOM Class Rules. I believe that material is unrestricted, only the density is restricted.
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Post by Chairman » 17 Apr 2005, 17:36

ptercinet wrote:If I realise a mix of resin and
something with higher density than lead but with effective density < 11.3
is it legal ?
Bonjour Pierre

Materials shall not have density greater than lead. As far as I can see, your mix is a mix of two materials, where each of these materials has a limit on permitted density. I believe (unofficially, of course!) that the rule has no application to an "effective" density of the mix, though I can see that this is an ingenious idea.
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Jamestj
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Post by Jamestj » 17 Apr 2005, 22:31

I understand that lead is prohibited in UK as sinkers for fishing lines since swans and other birds which swallow stones (to grind up food on account that they don't have teeth) tend to end up with lead in their gizzards and this causes their heads to droop. (This is not due to the weight of the lead which isn't much but is due to their internal chemistry being mucked up. I think that fishermen use tungsten paste, now)

The point made by VCinfocomms is interesting. Perhaps lead could be avoided 'cos it builds up in your body like mercury and many other heavy metals. I think lead affects your memory or is that mercury? I can't remember.

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