Sail Trim Online Series

A 4-part online series designed to deepen your grasp of sailing forces and trim while mastering advanced techniques for optimal speed.

4x 90 Min Sessions English Unlimited Access Downloadable Trim Simulator

Learn the fundamentals and intricacies of upwind and downwind sail trim with this series of online classes hosted by Bill Gladstone. The upwind sessions teach techniques to use angle of attack, sail depth, and twist for better speed, balance, and control in all conditions. The downwind sessions cover reaching and running trim with symmetric and asymmetric spinnakers, as well as non-spinnaker sailing under Jib and main. All sessions start with the basics before exploring advanced techniques to allow you to sail better and more confidently in light, moderate, and heavy air.

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Great in-depth explanations. I especially like the demos on the sail trim simulator. That helps to understand how to put the lessons in this class to practice.

Bill Gladstone is a complete master and expert!! He kept it fun and interesting, as well as moving along at a good pace.


This course is ideal for sailing enthusiasts seeking to master the art of efficient upwind and downwind navigation as well as sailors looking to enhance their skills with advanced techniques and insights. Additionally, racing teams and crew aiming for coordinated efforts to optimize performance will find valuable insights and strategies in this comprehensive online series.


Bicycles, bobsleds, sailboats - no matter what you race, you’ve got to be fast to win. If it’s sailboats you race or cruise, then this online course is for you. You'll learn the latest in sailing skills with an emphasis on practical, proven, real-world techniques that will help you sail faster. Even if you never race you’ll learn how to sail with better speed, balance, and control.



  • Sail Theory
    If you've ever wondered how sails work then this online course will explain the basics.
  • Angle of Attack, Depth, Twist
    Learn how the angle of attack, depth, and twist combine to control upwind power.
  • Sail Controls
    It's time to take the theory and put it into practice as we discuss how to use the controls on your boat to change the shape of your sails. The interactive Sail Trim Simulator allows you to see how changes in sail controls change sail shape and performance, while video clips show real-life trim and performance techniques.
  • Upwind Trim in All Conditions
    An in-depth look at how you can set up your boat and trim your sails upwind in a variety of different conditions. Including a special Trim Solutions section to solve the most baffling problems in upwind performance.


Learn how to optimize downwind performance with symmetric spinnakers.

Sailing downwind is easy. Optimizing performance downwind is tricky. Learn how to coordinate efforts of the full team/crew to provide subtle but critical improvements in downwind performance and how to control and optimize the spinnaker shape with refinements that take you beyond the basics.

  • Initial Spinnaker Trim
  • Reaching Trim
  • Running / VMG Trim
  • Light Air & Heavy Air Techniques
  • Pole Adjustments
  • Helming


Learn how to optimize downwind performance with asymmetric spinnakers.

Learn about downwind sailing without a spinnaker and how to set up and trim your main & jib while coordinating trim, helm, and crew weight to help to sail faster, deeper, and with more control.

  • Initial Spinnaker Trim
  • Reaching Trim
  • Running / VMG Trim
  • Heavy Air & Light Air Techniques
  • Tackline Trim
  • Helming
  • Non-Spinnaker Downwind Setup & Trim


The simulator models upwind trim and performance as never before. Years in development, the simulator uses the power of the North Sails Design Suite to model upwind trim and performance with unprecedented accuracy – in both the depiction of sail shape and performance data. Adjust every control. View from every angle. Test in a full selection of wind speeds and sea states. See the results.


The North U Performance Trim book gives complete coverage to upwind and downwind sail trim and boat handling, including mainsail and genoa trim, helming, and the trim and handling of both conventional and asymmetric spinnakers. Learn how the angle of attack, depth, and twist affect performance. See how changes in pole position change spinnaker shape. Understand your options for spinnaker takedowns. Special sections including boat handling skills and drills show you how to turn your crew into a team. Packed with illustrations, written to be read, the 208-page book will teach you techniques to sail faster.

The North U Performance Trim and North U Performance Racing Tactics books are NOT included in the registration fee but everyone who registers for the online class will receive a 15% off promo code to use on our online store - BUY NOW



Director of Education, North U

Bill Gladstone is the Director of the North U Performance Division of American Sailing. He is the author and creator of books, seminars, online classes, and clinics. Bill’s racing experience covers the spectrum, including everything from dinghies to maxis, ponds to oceans, and foredeck to helm. Bill has been teaching sailing and racing for over forty years throughout North America, Europe, and Asia. Graduates of his seminars and clinics number in the tens of thousands. They are winning races and cruising with confidence the world over.