IOMICA Forum

Hello IOM lovers,

Since I am planning to manufacture IOM sails just for fun I would like
somebody to again confirm the exact rule of measuring the main sail.
I find 2 different way of doing it on the internet.

1. To find the leach 1/2 point you use the method of Lester above.
The mainsail leach midpoint is found when you draw a 90 degree
line from the midpoint of a strait line between the forward Head point
and the Clew point.

2. The leach 1/2 point is found as the mid point if you fold the sail holding
the aft Head point and Clew exactly aligned. This is the exact leach 1/2 point

Whick one is the correct one ?
Since the IOM mainsail leach does not bend much the result is almost
the same. The difference is only a few millimeter.
When I measured my existing sails they were approved with either
method.
When I got my sails approved by a measurer guy he used method 2.

Still I would like someone here to confirm what method 2 SHOULD be used.

I put this question on the international IOM facebook group.
I though I would get the correct answer within 15 minutes.
NOBODY answered !!!

Thanks in advance
Magnus Modig

Last but not least, as there is no answer, here is mine with little experience even if I am not an official ISAF measurer

As far as I know, Method 1 is the right one. Then to find 1/4 points you repeat the same method from the 1/2 origin founded on the edge of the sail.

Is that clear enough ?

Regards

The answer to your question is found in the Equipment Rules of Sailing as follows.

G.5.2 Half Leech Point
The point on the leech equidistant from the head point and the clew point.

Where the "Head point" is on the luff or extended line of the luff.