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Still using flat windsurf sails? – the benefits of pre-shape

August 20th, 2019

Witchcraft’s Bouke Becker talks about the benefits of using windsurf sails with a pre-cut shape and why generally this is better for your windsurfing. It’s also why Witchcraft sails are becoming ever more popular. Read on to find out more.

What are the benefits of pre-shaped windsurf sails? It’s a question you may be asking yourself. Simply put sails with shape cut into them have:

-More light wind grunt.

-A higher top end.

-Easier to sail, less nervous. The angle of attack is less critical.

-You can use a smaller big size, reducing weight AND swing weight which is far more effective than using thin materials. Smaller sizes are also stronger when getting washed.

-Much bigger wind range, both natural and trim range.

-As battens are semi rotational, they do not poke as much in front of the mast and to flip the rig when jibing is just as easy. The rotation of the sail is also softer compared to completely full cut sails.

Here a Slayer 5.2 set completely full to deliver a lot of grunt:

 

Explanation:

To get power, we need to “bend” the wind in a fluent way. We all know that a deeper profile gives more power. Still, in side shore conditions, there are short moments where they also need to depower, go flat, preferably without flutter as flutter creates drag, for which full battens are better than 3/4er battens. Most sails on the market are completely flat or nearly flat when without wind. In such a sail the wind needs to push against the tension in the sail and the battens to fill the profile. If the wind is light, the sail remains too flat just when you need more profile. At Witchcraft we have given our wave sails a medium amount of seam shaping, half way in between a flat shape and a completely full shape. Seam shaping increases the wind range, you need less wind to bend the battens to get a full shape so it has more light wind power and when the wind increases, the profile stability is lots better as it no longer just depends on the battens. With the shape kept forward, the sail delivers the most power with the least drag, the angle of attack is easier to find and makes the sail less nervous. If you look at other air foils, the leading edge still has a lot of shape, even if designed for higher speeds:

To be able to depower the sail is also important for wave sailing but what often seems to be forgotten is that battens themselves want to go straight so very little is needed to make a sail with a medium amount of shape go flat.

Full sail, rigged for float n ride, still with the profile well forward and stable, the sail is touching the boom:

Moments later in the bottom turn, the sail becomes practically flat with the apparent wind being nearly zero:

And then in the top turn:

Of course you can also set a sail flatter:

The Karma 5.0 with 5 battens has a more locked in shape for a bigger wind range than the Slayer:

And each size up gets a bit more shape, as you can see with the Karma 5.9:

For many people, it is always hard to believe a small brand is ahead of the bigger brands. But it seems some brands are going in the same direction like Severne Pro or the 2020 GA Manic:

So as you can see there’s plenty of reason to be using windsurf sails with pre-shape like Witchcraft’s range. If you have any questions about any of our products then please free to give us a shout.