Take the guesswork out of when to make sail changes with our new Sail Crossover Chart feature, designed for cruisers and racers alike. The Sail Routing tool now shows you what sail to use at each stage of your route, based on your boat’s performance polars, sails onboard and the expected conditions. Whether it's time to change a sail or put in a reef, you’ll get a clear idea of what to expect and when.
Every sail change is highlighted on the sail routing map and routing summary in table format, so you can plan ahead with confidence and make smarter seamanship decisions.
What Is a Sail Crossover Chart?
A sail crossover chart shows which sail will perform best at specific true wind speeds and angles, and the point where one sail becomes more efficient than another.
For example, if you have a furling genoa and a furling staysail, the crossover chart will help you determine when you should change from one to the other.
Why Sail Crossover Charts?
Imagine you're planning a multi-day passage—whether a short coastal passage or heading offshore. You’ve got to make smart sail choices for performance and safety. That's where Sail Crossover Charts come into play:
Improve Safety: Reduce unnecessary sail changes in heavy conditions. Pre-planning on selecting the right sail reduces the need for extra sail changes when the weather shifts—fewer man-overboard risks, fewer interrupted nights.
Plan Smarter to Maximise Comfort and Speed: Choose the best sail before departure for the expected conditions. These charts reveal the wind angle and wind speed zones where one sail or combination of sails outperforms another, helping you pick the best sail combination for the forecast.
How to set up Sail Crossover Charts for your boat on the Forecast Site
How to read Sail Crossover Charts
The X-axis shows True Wind Angle (TWA).
The Y-axis shows True Wind Speed (TWS).
Colours indicate which sail is optimal.
To set up Sail Crossover Charts in the PredictWind Forecast Site for your sailboat:
Log in to the PredictWind Website.
Select Weather Routing > Sail Routing in the left menu.
Select Sail Crossover Chart in the top menu.
At the top of the page, under Edit Mainsail, click Import.
Either scroll to select from the list of pre-defined sail crossover charts below, or start typing your boat type into the search box.
If you do not find your boat, you can either build the sail crossover chart from scratch or select a similar boat to get started.
Sail crossover charts will be imported for both the Mainsail and the Headsail.
If you wish to set a different headsail only, scroll down the page and under Edit Headsail, click Import, as above.
How to view Sail Crossover Charts in Weather Routing on the Forecast Site
To view Sail Crossover Charts in Weather Routing:
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.
How to edit Sail Crossover Charts in Weather Routing on the Forecast Site
To edit Sail Crossover Charts in the Forecast Site Weather Routing:
Log in to the PredictWind Website.
Select Weather Routing > Sail Routing in the left menu.
Select Sail Crossover Chart in the top menu.
Click on the Sail Chart you wish to edit, e.g. Reef 3
Click Add or Remove to activate those tools, then click the segments on the chart you wish to edit, or click Rename.
When you have finished editing the Sail Chart, click on the sail chart name to deselect it.
Frequently Asked Questions
What happens if I have two sail charts overlapping, occupying the same sail crossover chart area?
If two sail charts overlap, both sails will be included in the Sails table, as shown in the example above.
How many Sail crossover charts are there? Is my boat included?
PredictWind has launched this new feature with over 1000 sail crossover charts! There will likely be a suitable starting template you can begin with and edit from to suit which sails you have and how you sail your boat.
If your sailboat isn't in the list, you can always select from a similar boat , or build up your sail crossover chart from scratch based on sailmaker specifications.
Please note: it is extremely important for you to customise the sail crossover chart for your boat, think about when you reef. How many reef points do you have, do you have a trysail/storm Jib.
Does this work for all sailboats?
Yes. As long as you know your sail inventory, the tool is useful for monohulls and catamarans alike.
What if I have overlapping sails?
If sails cover similar True Wind Speeds and/or True Wind Angles, the crossover will show an overlap, showing you flexibility in your sail plan.
What defines a Headsail?
Any sail not the Mainsail in front of the main mast, so includes asymmetrical spinnakers, spinnakers and Code 0s.
Can I export the Sail Crossover Chart?
Yes, you can export the chart, which saves it to your PC computer or Mac. Click the Export button to save the Sail Crossover chart as a text file.
Pro Tips for Cruising Sailors
Avoid nighttime sail changes: Plan for sail changes before nightfall.
Match the chart to your polar data: Make sure your boat’s polars and sail inventory are accurate for best results. Have marks on your Genoa Furler corresponding to your sail crossover chart.
Print and post: Keep and laminate a copy of the sail crossover chart near the nav station or helm as a quick-reference guide. You can screenshot the chart to print it, or print to PDF in your browser.
Pro Tip For Racing Sailors
Allows the team to make decisions on sails to take for the race.
Allows the bow team to have a heads up of sail changes during the race, determine the stack of sails below, run halyards, run the 3rd reef line and change sheets early.