J120.org

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

123456

Chord Length

620600560500420320

Below #2

0336676101613561696

L E Radius

15.414.913.912.410.47.9

Xc Station

1/2 (Yc)

.0125

14.714.213.311.89.97.6

.025

20.319.618.316.313.710.4

.05

27.426.524.922.218.714.1

.075

32.631.529.426.222.016.7

.10

36.335.132.829.324.618.8

.15

41.440.137.133.428.121.4

.20

44.443.040.235.930.123.0

.25

46.144.641.637.131.223.7

.30

46.545.042.037.531.524.0

.40

45.043.540.636.330.523.2

.50

41.039.737.133.127.821.1

.60

35.334.231.928.524.018.3

.70

28.427.525.622.919.214.7

.80

20.419.718.416.513.810.5

.90

11.010.610.09.07.76.0

1.00

1.51.51.51.51.51.5

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.