Measurers Corner

Measurer’s Interpretations and Recommendations

Topic:Jib Measurement
Question:Is there a better means to measure the jib head apex?
ID Number:000025
Short Answer:Yes 
Answer:Current Rule: The measurement "apex" points shall be determined by the intersections of the extensions of the respective outside edges or any sail. Such extensions should be taken to a length of 18 to 24 inches (along the actual edges of the sail). Cringles, thimbles or other hardware that are partly or entirely external to the sail shall be disregarded. 
Action Date:2010-02-24
Thu Nov 30 23:13:37 2023
2008-10-29Richard RobbinsMeasuring the apex of the jib head is quite problematic mostly because of luff clips. Using the extension of the sides is open to interpretation and there can be an inch or so of difference between measurers. This difference then effects the luff and leech length as well as the location of the 25% and 50% width.
2008-10-29Richard RobbinsFor the jib head I would propose something like this:
"The jib head measurement point shall be the apex of a right triangle with height 18" (luff side) and base of 7" within which all cloth of the jib head lies."

This approach is less prone to measurer interpretation. Essentially what one does is to cut out on paper a triangle (18" x 7') and lay this under the sail as low as possible where the cloth lies inside the triangle. This is easy to do and would not give differing results as to the apex.
2008-10-29Richard RobbinsISAF Technical Documents indicate:
Corner Measurement Point - To find a corner measurement point may require the extension of the line of the edges of the sail adjacent to the point. Where the line of extension is obvious, it should be used. Placing a batten along the edge can often help to give a true extension continuing any curve. Making the lines on paper taped to the underside of the sail helps to retain the point during measurement. Where the line of the extension is uncertain and not repeatable leading to inconsistent measurement points, the measurement of the sail should be refused.
ISAF Corner Measurement
2008-11-13ANDREW BURTONHas this been a problem? I certainly haven't heard about it. I know North is making their sails the same way they have for years, has another sailmaker come in and started doing something different?
2009-10-06Richard RobbinsThe intention here is not to effect how sails are made and has not come from any sailmaker issue. This is purely being proposed as a convenience to measurers and is designed to NOT effect sail design (current and new). I have seen different measurers come up with differing appex extension measurements. This rule is meant to make the jib apex measurement more repeatable.
2009-11-16Bam MillerHaving been Fleet 5 measurer for a number for years; I have made a hinged jig for finding the apex of the head of the jib, or the clew and tack of the main. Would it be nice if they had a head width and luff length dimension like the Ethcells, J-24, Melges 24 etc; Yes. Does what we have now work? Yes. Easy? No. But it has worked for how many years. No change needed.
2010-02-12Richard RobbinsBased on unanimous vote at Technical Committee meeting of 2/10/2010 the following will be added to §V-8.6: The jib head measurement point shall be the apex of a right triangle with height 18" (luff side) and base of 7" within which all cloth of the jib head lies.