J120 front copy

J/120 Mainsail Trim


Here is a North Spectra 295TX FullBatten Gatorback mainsail in 14 - 16 knots true wind with runner and backstay at full tension to flatten the sail. A key in wind speeds of 15+ knots is to sail the boat with less than 24 deg. heel and max backstay and runner. In addition to flattening the sails, this stabilizes the rig.
Max VMG.... GO FOR IT!

  • Hike your buns off! Less heel angle means more keel immersion.
  • Sail with minimum heel and minimum helm motion for less drag. Use the mainsheet to control heel before the tiller!
  • Tighten the backstay & runners to bring the headstay closer to the vertical centerline plane while maintaining mainsail shape. The headsail can then be sheeted harder without compromising the slot.
  • Increase sheet tension to the mainsail and headsail to bring leeches closer to the vertical plane.
  • Adjust mainsail controls to keep the draft just ahead of 50%. Add sheet tension until the top telltale stalls more than 30% of the time, or until speed drops away from target.
  • Sail for speed! Sail the boat at target speed to create maximum water flow around the keel, producing more lift.

This 12,600 dpi 30L mainsail is set-up for power and maximum painting in 10 knots true wind. If you compare the boom angle and top batten, you’ll see the top batten about 2-30 above boom parallel. This is an effective tool to maximize pointing once the boat is at full speed. If the speed drops off for any reason, ease the sheet a few inches and it will probably climb right back up.

J120 tune 010

J120 tune 011

J120 tune 012