Viper 640 M-7 Mainsail

2019 & 2018 Worlds!

The M-7 mainsail was designed to compliment a simple tuning system that will help keep you up to speed in a variety of conditions. Chocking the mast in light air induces the proper amount of headstay sag; blocking the mast back and tensioning the lowers straightens the headstay for windier conditions, especially when vang sheeting. By optimizing the full length batten locations, we were able to maximize the sail’s size at measured girth points. We also relocated the spreader window to make the jib leech telltale easier to see.

Standard Features

  • Sail numbers
  • Insignia
  • Trim stripes
  • Vision window
  • Jib leech window
  • Sail bag


  • Extra set of battens