Whatever sails you're using, which won't be leaf, make sure you have plenty (i.e. 40-ish units) of the material to repair them. Also, it'll help if you can move fast to repair sails, it helps, so be hydrated.

Your island should also be at a height of roughly 500m as you approach the barrier. This gives you flexibility in going up or down depending on how best to avoid obstacles. In order to see in front of you, explore the different views you can choose while piloting the island. You may find one easier to use than the other.

The barrier is made of three things: small boulders, big boulders and dark round balls. Small rocks are harmless. The other things are not your friends, and will tear your sails apart. The longer you take to repair them, the more of your progress through the barrier you'll lose. So it's a bad idea to have your helm at the front of the island, and all your sails at the back. Move at least a couple of sails within a short run of your helm.

As you get into the barrier you're basically looking for holes to sail through. You can stop temporarily, just to let something bad go past you. I don't think you can be hit from behind, so it shouldn't be too dangerous. You can go left or right or up or down. If you do get hit, it's not huge problem. You'll just have to repair your sails.

You don't need to aim for any specific point. Orient yourself by keeping an eye on where the storm is on your compass: it should be roughly in front of you or behind you, depending on which way you're heading. It is more important to find a big clear piece of air to sail through than it is to take the shortest route straight through the barrier.

Once you've got through a little of the barrier, there's a sliding display at the top of your screen showing how far you are through. You're aiming for that slider to get three quarters the way across. At that point it gets easier instead of harder.

If it all goes wrong, it's good to know that, although it might look otherwise, the only thing on your island that can be damaged is your sails. May the skies smile upon you.