J120 front copy

J/120 Mast Setup Guide


The set-up measurements used onboard J/120 Fatal Attraction are listed below. The headstay length is taken from the centerline of the pin (A) passing through the upper mast tang to the centerline of the pin at the stemhead.

- Pin-to-pin without any backstay tension- 16.11 m (52.85 ft.)

- Pin-to-pin with 4000 lbs. backstay tension- 16.15 m (52.98 ft.) 16.09 m without top toggle

J120 tune 001

Masthead measurements are taken with the raised genoa halyard two-blocked at the sheave.

- Masthead to shackle on furling drum (B- )15.25 m (50.03 ft.)

- Masthead to pole end (extended)- 17.41 m (57.11 ft.)

- Masthead to stemhead pin- 16.60 m (54.46 ft.)

*This measurement was taken outside the pulpit in order to get an accurate measurement around the furling drum.

    Masthead to front of headsail track- 14.83 m (48.65 ft.)
    Masthead to back of headsail track- 15.08 m (49.47 ft.)
    Masthead to front of #3 track- 14.73 m (48.32 ft.)
    Masthead to back of #3 track- 14.78 m (48.49 ft.)
    Masthead to chainplate pin centerline- 15.80 m (51.83 ft.)
    Masthead to 2nd spreader- 10.62 m (34.84 ft.)
    Masthead to 1st spreader- .68 m (18.63 ft.)

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While underway, double-check that the main halyard is hoisted to the black band (C). This is an often overlooked detail that will affect luff tension and sail shape, especially in a breeze. Be careful not to raise the jib halyard too high (D), of the headfoil will not rotate properly from tack to tack.

J120 tune 003

Right: Position mast butt so that attachment bolts are located in middle of slots in mast base

J120 tune 004