J120.org

Official Class J/120 Keel Offsets

All Dimensions in mm.

Yc half widths represent Minimum J/120 Class dimensions

Chord Lengths & Depths represent Maximum J/120 Class dimensions

Section	2	3	4	5	6	7	8	9	Tip CL
Chord Length	1530	1430	1330	1230	1210	1370	1570	1770
Below #2	0	300	600	900	1000	1100	1200	1300
L E Radius	15.0	19.3	24.5	30.9	33.5	38.9	44.5	50.0	35.0
Xc Station		1/2 (Yc)
.0125	22.7	25.0	27.1	29.3	30.3	34.7	39.7	44.8	23.5
.025	31.3	34.4	37.4	40.5	41.8	47.9	54.9	61.9	29.4
.05	42.6	46.8	51.0	55.1	56.9	65.1	74.6	84.1	37.0
.075	50.4	55.3	60.2	65.1	67.2	77.0	88.2	99.4	42.8
.10	56.2	61.7	67.1	72.6	75.0	85.5	98.3	110.8	48.3
.15	64.1	70.4	76.6	82.9	85.6	98.0	112.5	126.5	53.8
.20	68.8	75.5	82.2	88.9	91.8	105.2	120.5	135.8	56.7
.25	71.3	78.2	85.2	92.1	95.1	108.8	124.7	140.5	58.0
.30	72.0	79.0	86.0	93.0	96.0	110.0	126.0	142.0	58.8
.40	68.9	75.6	82.4	89.1	92.0	105.3	120.6	135.9	58.0
.50	62.1	68.1	74.2	80.2	82.8	94.8	106.6	122.4	56.7
.60	51.7	56.7	61.7	66.7	68.9	78.9	90.4	101.9	54.6
.70	40.0	43.9	47.8	51.7	53.4	61.1	70.0	78.8	51.2
.80	27.5	30.2	32.9	35.6	36.8	42.1	48.2	54.3	42.8
.90	14.4	15.8	17.2	18.6	19.2	22.0	25.2	28.4	24.4
1.00	1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0

Notes:

1. LEADING EDGE PROFILE SWEEPBACK FROM SECTION 2 THRU 9 IS 0.45 HORIZONTAL/1.00 VERTICAL OR 24.22 DEGREES

2. TIP OF KEEL BELOW SECTION 9 IS DEFINED BY CONSTRUCTING ELLIPSE BETWEEN SECTION 9 OFFSETS AND TIP CENTERLINE OFFSETS AT EACH Xc STATION.

3. LEADING EDGE PROFILE FROM SECTION 2 TO SECTION 8 IS A STRAIGHT LINE.

4. SECTION 2 IS LOCATED 230MM BELOW HULL AT TRAILING EDGE