VC Measurement: Lawrie Neish – CAN
“vcmeasuring” at “”


Sail Maker Self-Certification Licence – Draft Version 1.4 (2004Jan23)

Sail Measurement Guide for the use of IOM measurers by IOMICA
This is a short summary the ISAF Guide to Sail Measurement 2001-2004. The full guide is available at

How do I register and/or get a certificate for my IOM

Sail Measurement Matrix
The sail measurement matrix no longer forms part of the IOM Class Rule document and is provided here for information purposes only by popular demand. Be aware that the mainsail diagram inaccurately depicts the Leech Points equidistant along the leech measurement(C). For a correct definition of the Leech Points see ERS G.5.

Class Rules According to the current IOM Class Rules (2007),

where an Owner seeks registration and certification of a hull which is to be used with previously measured rig(s), there is no need to re-measure and re-submit a Measurement Form in respect of such rig(s) if the rig’s/rigs’ Measurement Form has/have previously been accepted by the Certification Authority.


The intent of the IOM class is to offer accessible radio sailing in an International class at moderate cost. An IOM Owner takes all responsibility for racing an IOM within the class rules. With these principles in mind, it is only necessary for an Owner to request his or her Certification Authority to transfer an existing Measurement Form to the new hull Certificate.

Measurement Guides

Bumper Measurement

The following diagram provide some guidance on measuring an IOM bumper. The class rules state that the forward 10 mm of the hull shall comprise elastomeric material — that is, be a bumper. The Equipment Rules of Sailing say that this measurement shall be taken with respect to the waterline. So the bumper in diagram “A” is NOT legal, because part of the forward 10 mm of the hull is not elastomeric. The bumpers of “B” and “C” are permitted, since all of the forward 10 mm of the hull is a bumper, even though in “B” this bumper thins out to 0 before it reaches the waterline.

Hull Hollows

The following diagram provides some guidance on hull hollows. The class rules state that hollows deeper than 3 mm are prohibited. This measurement is taken parallel to the waterline. If the “hollow” is measured in some other plane, the 3 mm restriction does not apply. All of the illustrated hollows are permitted, provided that, when measured parallel to the waterplane, none exceed 3 mm in depth.
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