J120 front copy

Official Class J/120 Rudder Offsets


All Dimensions in mm.
Yc half widths represent Minimum J/120 Class dimensions
Chord Lengths & Depths represent Maximum J/120 Class dimensions

Section 1 2 3 4 5 6
Chord Length 620 600 560 500 420 320
Below #1 0 336 676 10116 1356 1696
LE Radius 15.4 14.9 13.9 12.4 10.4 7.9

Xc Station
   
1/2 (Yc)
     
.0125 14.7 14.2 13.3 11.8 9.9 7.6
.025 20.3 19.6 18.3 16.3 13.7 10.4
.05 27.4 26.5 24.9 22.2 18.7 14.1
.075 32.6 31.5 29.4 26.2 22.0 16.7
.10 36.3 35.1 32.8 29.3 24.6 18.8
.15 41.4 40.1 37.1 33.4 28.1 21.4
.20 44.4 43.0 40.2 35.9 30.1 23.0
.25 46.1 44.6 41.6 37.1 31.2 23.7
.30 46.5 45.0 42.0 37.5 31.5 24.0
.40 45.0 43.5 40.6 36.3 30.5 23.2
.50 41.0 39.7 37.1 33.1 27.8 21.1
.60 35.3 34.2 31.9 28.5 24.0 18.3
.70 28.4 27.5 25.6 22.9 19.2 14.7
.80 20.4 19.7 18.4 16.5 13.8 10.5
.90 11.0 10.6 10.0 9.0 7.7 6.0
1.00 1.5 1.5 1.5 1.5 1.5 1.5

Notes:

1.  SECTIONS ARE IN HORIZONTAL PLANE

2.  LEADING EDGE SWEEPBACK IS 16 DEGREES AFT OF VERTICAL.

3.  AXIS OF RUDDER POST ENTERS TOP OF RUDDER AT RIGHT ANGLE. 120MM AFT OF
LEADING EDGE MEASURED ALONG RUDDER TOP

4.  ANGLE BETWEEN 1/4 CHORD LINE (.25 Xc) AND HORIZONTAL PLANE IS 75 DEGREES.

5. 1/4 CHORD LINE (Xc) IS A STRAIGHT LINE.