North Sails' J/109 Tuning Guide

Base Settings for 10-15 knots True Wind Speed

Headstay Mast Butt Max J Pre Bend Upper Shroud V1 Lower Shroud D1 Intermediate Shroud D2
2260mm 460mm 4050mm 20mm 52 Units 27 Units 15 Units
» Shroud tensions measured on RT-10 Loos gauge
» Download North's Quick Tune Card (pdf file)

© North SailsHeadstay is measured using swing arc method. Use jib halyard pulled down to top of black band on mast - swing forward to mark headstay. Measure distance from mark on headstay to deck at stem.
© North SailsThe mast butt is measured from forward face of mast to aft edge of bulkhead. This corresponds to forward most position in the slider.
© North SailsPre-Bend is measured at point of maximum deflection between S1 and S2 (left).
 
© North SailsJ Dimension is measured from intersection of stem at shear to forward face of mast (left.)

Shroud Adjustments Matrix

True Wind
Speed
Upper
Shroud
V1
Lower
Shroud
D1
Intermediate
Shroud D2
0-5 knots
6-10 knots
11-14 knots
15-18 knots
19-21 knots
-2.5 turns
-2.5 turns
Base 52
+2 turns
+3 turns
-2 turns
-1 turn
Base 27
+1.5 turns
+2 turns
-2 turns
-1 turn
Base 15
+1.5 turns
+2 turns