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PHRF Measurement Guidelines


Note: To determine actual sail areas "Sails shall be measured in a dry state, with just sufficient tension to remove wrinkles across the line of the measurement being taken. Corners of the sail will be taken at the intersection of the projections of the adjacent sides. As an option, mainsail P and E dimensions may be taken between black bands on mast and boom. Sails measured thus may not extend beyond the black bands when racing."*

*From IYRU measurement instructions, 1974, Section III, Paragraph 1, Period 1. (Same as IOR).


Definitions:

"I" The Foretriangle height measured along the foreside of the mast from the main deck "datum" to the top of the Jib halyard sheave.

NOTE: The height of the deck used as datum for "I" shall be taken as 4% of beam above the shear line abreast of the mast. For flush deck boats i.e. TANZER 22-26, CAL 28 and MORG 27 whose cabin extends athwartships to the shear line, use the stripe along the hull which represents the shear line.

"H" Same as "I" but measured to top of spinnaker sheave, if same as "I" this measurement is not necessary.

"J" Distance is measured from the foreside of the mast to the point where forestay attaches to deck or bowsprit, in a direction level with the waterline.

"P" Luff length of mainsail from tack to head.

"E" Foot length of mainsail along boom from tack to clew of sail. In the event the clew of the mainsail is carried below the top of the boom where it intersects the mast (Boom Droop), measure the "E" along the slope of the mainsail.

"MGM" Mainsail Mid-Girth Measurement, the points of measurement are determined as follows:
     1. By folding the head of the sail to the tack and marking the midpoint of the Luff.
     2. By folding the head of the sail to the clew and marking the midpoint of the Leach.

"MGM" is the measured distance between the Luff and Leach marks.

"MGU" Mainsail Upper-Girth Measurement, the points of measurement are determined by folding the head of the sail to the Mid-Girth measurement points and marking the three-quarter points for the Luff and Leach. "MGU" is the measured distance between the resulting Luff and Leach marks.

"HB" Headboard. Measure the maximum fore and aft dimension from the Luff of the mainsail to the aft edge of the Leach at the widest part of the Headboard.

"LP" LP is the distance from the clew of the jib to the luff line of the jib in a direction to cross the luff at 90°. If in doubt about clew location, project the leach and foot to the point of intersection.

"LLJ" Luff Length Jib is the measurement from the Tack to the Head of the Jib. If in doubt about the Tack and Head location, project the Luff, Foot or Leach to the point of intersection.

"LLS" Luff Length Spinnaker is the greatest length of Spinnaker Luff and Leach measured around the edges of the sail.

"G" Is the Girth of the spinnaker. This is the maximum width of the spinnaker measured from Luff to Luff with the spinnaker stretched flat; measured parallel to the Foot. (Same as SMW in IOR)

"SPL" "Spinnaker Pole Length". The length of the Spinnaker Pole, when in its fitting on the mast, and set in a horisontal position athwartship, measured from the centre line of the yacht to the extreme outboard end of the pole and fittings used when the Spinnaker is set.

"WPL" "Whisker Pole Length". The distance from the vertical centre line of the forward face of the Mast to the centre of Clew cringle (or "D" ring of clew) of the Jib to which the pole is attached: measured in a direction perpendicular to the vertical centre line of the forward face of the Mast.

Formulae:

Standard Sail Area (as determined by rig measurements):

Measured Jib Area = 1.02*I*1.50*J/2 = 0.765*I*J
Measured Spinnaker Area = 0.87*I*1.80*J = 1.566*I*J
Measured Mainsail Area = 0.59*P*E
Average Headsails = 1.032*I*J


Actual Sail Area (as determined by sail measurements):

Actual Jib Area = 0.50*LLJ*LP
Actual Spinnaker Area = 0.87*LLS*G
Actual Mainsail Area = (3*E+4*MGM+4*MGU+HB)*P/12


Cruising Spinnaker (Leach and Luff measurements differ, no pole):

Actual Area = 0.72*(Luff L + Leach L)*G/2



For further information contact your local club measurer or
Contact: NSYA

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