J/24 Tuning Tip: Settings to Power Through Chop and Swell


By Tim Healy, Quantum Newport


The Newport Regatta was held July 13-15 on the waters of the Atlantic Ocean about three miles offshore. Participating in the event were 27 J/24s competing for the J/24 North East Regional Championship, with many of the top boats preparing for the J/24 worlds in September. 


Boats powered by Quantum® sails finished 1st, 3rd, 4th, 5th, 7th, 9th 10th at this event!


The conditions were very similar all three days. The wind was from the southwest and the velocity ranged from 5-14 knots. The sea state was small ocean swell with moderate chop on top of the swell.


Our rig was set at 20 on the uppers and 15 on the lowers for most of the regatta except for two races when the breeze was constantly above 12 knots. Every other race we had lulls below 8 knots. Our light air setting is 20-15, which is also our base for initial rig set-up and tuning. At this setting we are also looking for pre-bend between 2.25” and 2.5” and negative 2.5-3.5 fingers for headstay sag. It is important to disconnect one of the legs of your backstay to get the correct headstay measurement.


Headstay sag was very important to be able to power through the chop and swell in the ocean during the Newport Regatta. Headstay sag by itself will add depth to the genoa; but if it is not accompanied by a significant amount of genoa halyard ease, it will disproportionately load the depth into the very front of the genoa and not have the desired effect on the overall shape. This is what is referred to as a knuckle-forward shape; this may be good for flat water but not for chop. When the genoa halyard is eased, the depth is further increased and the draft also moves back in the sail (to about 40% back from the luff) at the same time. This deep, powerful shape will help you keep your boat speed up in the chop and will also widen your groove to allow you to steer around the chop when needed.


When there is an especially bad set of waves, and the headstay begins to pump uncontrollably, the wind will no longer have an even flow and the sail will stall, decreasing the power generated by the genoa. The best way to temporarily solve this problem is to put a slight amount of tension on the backstay to reduce the whip of the mast and to stabilize the headstay. As soon as the bad set of waves is gone, release the backstay.

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