In this session, we explore one of the most powerful, yet often overlooked tools in offshore and performance cruising: Sail Crossover Charts.
Whether you're preparing for a trans-ocean passage or optimising your setup for coastal racing, understanding which sail to fly — and when — can dramatically improve your boat speed, comfort, and safety.
Craig Smith, Delivery Captain and PredictWind Weather Routing Specialist, will walk you through:
What a crossover chart is, and how to read it.
How the custom Sail Crossover Chart is created for your boat.
The benefits of matching your true wind angle (TWA) and true wind speed (TWS) to the optimal sail.
How to set up Sail Charts in your PredictWind account.
Why you should be using the Sail Charts feature and how it can help you be faster around the race course.
How this tool is an essential safety tool, saving you from guesswork and letting you plan more confidently, especially when weather routing offshore.
You’ll also hear real-world examples, best practices for sail selection, and answers to common user questions.
Sail Crossover Charts for Yacht Racing
Sail Crossover Charts for Cruisers
What are Sail Crossover Charts?
Sail Crossover Charts are graphical tools that show which sail is optimal for any given combination of true wind angle (TWA) and true wind speed (TWS).
These charts:
They are custom-built for your boat by you, based on a suggested template.
Allow you to see overlapping zones where multiple sails are viable.
Help eliminate the guesswork when transitioning between sails (e.g., Code Zero vs A2).
Are especially useful when planning routes offshore, where sail changes are more involved and costly.
You can access your Sail Crossover Chart from the Weather Routing > Sail Routing > Sail Crossover Chart page in the PredictWind Forecast Website. The chart visually displays which sail gives the best performance at each wind condition.
Frequently Asked Questions (FAQs)
What is a Sail Crossover Chart used for?
A Sail Crossover Chart helps you decide which sail to use for the best performance based on the true wind speed and angle. It’s essential for efficient passage planning, especially offshore, where switching sails can be complex or physically demanding.
What do the colours and lines mean?
Each colour represents a specific sail (e.g., Jib, Code 0, A2). The lines show the boundaries where one sail starts to outperform another. The zones in between (overlaps) indicate areas where either sail is viable, helping you choose based on comfort, crew effort, or risk.
Can I customise my chart for my sail inventory?
Yes, you can add or remove sails in your Sail Crossover Chart page. Update your chart to reflect your custom sail setup, giving you personalised guidance based on your actual inventory. Many boats are in the list available as starting templates based on the expected sails you may have. Please use this, then adjust it to suit the sails and way you like to sail. If your boat is not in the list, you can build it from scratch in about 15 minutes.
How is this better than just checking polars?
Polars tell you your potential speed, but doesn’t explicitly say which sail to use. Crossover Charts overlay this info visually, so you can make decisions faster and with greater confidence, especially when planning days ahead.
Can I use this chart in the PredictWind App while sailing?
Yes, it’s available to view when you run a weather route:
Log in to the PredictWind Website.
Select Weather Routing > Sail Routing in the left menu.
Click the Blue down arrow, top right of the screen, to run a Sail Route.
Click on Tables > Sails (far right).
The tables include timing and guidance for recommended Mainsail and Headsail setups. The blue PredictWind icon to the right of the table indicates a sail change of either Mainsail or Headsail at each required time during the passage.
To read more about how to create and use Sail Crossover Charts, see: How to use Sail Crossover Charts.