Origin of I, J, P, E rig measurements?

[ds797]

So we have the "standard" rig measurements of I, J, P and E.... but I am curious as to where they originated from... I guess I mean what do they stand for? None of them seem to be "initials" of the name of a dimension! Idle curiosity thats all!

 

[scottie]

Perhaps they are just where they fell on the list Alphabetically

 

[wombat88]

Is there an initial for roach?

 

[Roberto]

Is there an initial for roach?

The first time I saw those initials was in the IOR measuring rules, there were letters or groups of letters for a lot of elements, for rig, sails, hull, propeller etc. On the mainsail they measured how much each batten was protruding from a line head-to-clew, there was a limit beyond which penalties were applied.
Or for example sail area was measured using -among others- JC, JC was a "corrected J": they measured J (base mast to forestay) and the Spinnaker Pole length, the bigger was taken as JC, which of course led to having all spinnaker poles maximum length equal to J. Also, there was a penalty for genoas having an LPG (perpendicular from clew to forestay) grater than 1.5 J, which led to genoa #1 being all 150%, and so on.
There were letters for canoe body draft, freeboard, beam etc taken at various fore and aft sections of the hull, and at various spacing from the centerline: as the draft which "counted" most in the rule for determining displacement was one at some distance from the centerline, and not the one at the centerline, all hulls had a flat underbody in their central area sections.
Also, hull length was determined comparing two sections fore, and two sections aft, in particular their girth: the more the girth difference, the more the rule "thought" the boat was pointy and the less length was considered: that created those horrid "bumps" in the aft section at the rudder, the one aft section girth was reduced, the rule was attributing a lower dynamic length, hopefully the worst water flow at the bump was less important than the gain in "measured" length.

 

[Plomong]

The first time I saw those initials was in the IOR measuring rules, there were letters or groups of letters for a lot of elements, for rig, sails, hull, propeller etc. On the mainsail they measured how much each batten was protruding from a line head-to-clew, there was a limit beyond which penalties were applied.
Or for example sail area was measured using -among others- JC, JC was a "corrected J": they measured J (base mast to forestay) and the Spinnaker Pole length, the bigger was taken as JC, which of course led to having all spinnaker poles maximum length equal to J. Also, there was a penalty for genoas having an LPG (perpendicular from clew to forestay) grater than 1.5 J, which led to genoa #1 being all 150%, and so on.
There were letters for canoe body draft, freeboard, beam etc taken at various fore and aft sections of the hull, and at various spacing from the centerline: as the draft which "counted" most in the rule for determining displacement was one at some distance from the centerline, and not the one at the centerline, all hulls had a flat underbody in their central area sections.
Also, hull length was determined comparing two sections fore, and two sections aft, in particular their girth: the more the girth difference, the more the rule "thought" the boat was pointy and the less length was considered: that created those horrid "bumps" in the aft section at the rudder, the one aft section girth was reduced, the rule was attributing a lower dynamic length, hopefully the worst water flow at the bump was less important than the gain in "measured" length.

A few months ago I was looking for information on the IOR measuring rule, and the elements that fed into the final calculation, with little success. Do you know where I might find a complete list of all elements included in the calculation, including corrections applied, etc ??

Plomong

 

[anoccasionalyachtsman]

A few months ago I was looking for information on the IOR measuring rule, and the elements that fed into the final calculation, with little success. Do you know where I might find a complete list of all elements included in the calculation, including corrections applied, etc ??

Plomong

I'd imagine that the Rating Office would have the ability to print a copy. This thread has reminded me of how annoyed I am that I chucked a copy of the rule away about three house moves ago.

 

[Plomong]

I'd imagine that the Rating Office would have the ability to print a copy.

Would that office be of the IYRU, or some other international organisation ?? Which one ???

Thanks for the pointer.

Plomong

 

[anoccasionalyachtsman]

Would that office be of the IYRU, or some other international organisation ?? Which one ???

Thanks for the pointer.

Plomong

RORC Rating Office

 

[Roberto]

A few months ago I was looking for information on the IOR measuring rule, and the elements that fed into the final calculation, with little success. Do you know where I might find a complete list of all elements included in the calculation, including corrections applied, etc ??

Plomong

I do not know if there is anything available online. I have all the paper documents in my former home, unfortunately not here where I live. The booklet looked similar to a pilot book with corrections : every year new additions and modifications were made, one had to cut and glue the strips of paper over the relevant pages of the rule booklet.

 

[Plomong]

RORC Rating Office

Thanks, will contact them and see how it goes.

Plomong

 

[Plomong]

I do not know if there is anything available online. I have all the paper documents in my former home, unfortunately not here where I live. The booklet looked similar to a pilot book with corrections : every year new additions and modifications were made, one had to cut and glue the strips of paper over the relevant pages of the rule booklet.

A document such as you describe, for a known version (e.g. V23.6 30-June-1988 or whatever) would suffice. Problem is how to locate such doc !!!

It doesn't need to be the most recent version, just that of a known version and/or date.

Plomong

 

[Cariadco]

So we have the "standard" rig measurements of I, J, P and E.... but I am curious as to where they originated from... I guess I mean what do they stand for? None of them seem to be "initials" of the name of a dimension! Idle curiosity thats all!

Great Question. Hope you and we, find out the answer.

 

[Roberto]

A document such as you describe, for a known version (e.g. V23.6 30-June-1988 or whatever) would suffice. Problem is how to locate such doc !!!

It doesn't need to be the most recent version, just that of a known version and/or date.

Plomong

I have it in Italy, the problem with all this Covid mess is I might get it no sooner than Christmas holidays period, at best and if we will be allowed to move.

ps I used those rules to design a One Tonner when the rules changed and put one tonners rating limit at 30.5', we even came 2nd place in a local yacht design contest for such boat

 

[Plomong]

I have it in Italy, the problem with all this Covid mess is I might get it no sooner than Christmas holidays period, at best and if we will be allowed to move.

There is no hurry -- I'm retired from the rat-race of project milestones (or should that be millstones) some time now, so take tasks one step at a time.

ps I used those rules to design a One Tonner when the rules changed and put one tonners rating limit at 30.5', we even came 2nd place in a local yacht design contest for such boat

Way beyond anything I could attempt. I once toyed with the idea of assembling a kit boat (Hunter 32 type), but the RCD and reality, timewise, stood in the way.

 

[Cariadco]

Perhaps, the following.......

I for "'ight" of course;
J for "Jeez, this is a big genoa";
P for Pathetically small IOR main;
E for "Eeeee! Watch your head on that droopy boom when we gybe."