Can I sail into the wind?

追加: 2026-05-31

[00:00:00]How is it possible to sail upwind? This doesn't make any sense. So, right now I'm sailing downwind. See, this is the wind direction. This is my indicator.

[00:00:08]And I can understand this. You see, the wind is pushing me this direction. This makes sense. But now let's make a wind like this.

[00:00:15]So, I'm going to adjust the sail a little bit.

[00:00:18]And my indicator shows the wind from the side. So, does it make sense? Well, maybe, you know, kind of it's pushing like this. But absolutely no sense once I start sailing upwind. So, I'm going to adjust the sail for upwind.

[00:00:32]And now my wind is coming like this. And I'm actually accelerating. See? I'm actually accelerating. Doesn't make sense.

[00:00:41]You see, the wind is coming like this, pushing me backwards, but I'm actually going faster forward. And it is because this sail is creating a lift, just like the airplane wing lifts the airplane in the air, but the wing is now like this.

[00:00:55]Let me show you. It's very easy.

[00:00:59]The wind is coming like this, and half of the wind goes on this side, the other half goes on that side. Now, by the physics, they start together, and they have to finish on the back together. But because this sail has this shape, so there's longer way than here. Let me show you. So, you see, it has this shape.

[00:01:16]Now, the wind on that side has to go faster to catch up with this guy, which means it creates high pressure on this side and low pressure on that side. It's identical to the airplane wing, and that's how the airplane can fly. But now the wing is like this.

[00:01:31]So, now this is not wind anymore. This is the aerodynamic force that the sail is producing. You see? It is pushing me forward and sideways. You see? Something like this.

[00:01:42]Now, because I want to get upwind, I don't want to go sideways. So, that's why we're using these uh dagger boards.

[00:01:48]So, let me pull this out. Oof.

[00:01:53]So, this is a dagger board. See, very thin here, very wide, and it's basically counteracting uh you know, these forces so that the boat doesn't go sideways. So, if this is out, the boat is going to go, you see, like this.

[00:02:06]A lot sideways. When I push this in, the boat is going to go start going like this. We can never go straight. There's always going to be a little bit of sideway movement, but we minimize it with this. Now, how do I How am I going to get up there? Because I need this minimum angle, you see? Because if suddenly Let's put this wind again.

[00:02:26]If I turn straight upwind, this is a great method to stop a boat.

[00:02:30]So, I need See, all the sail just lost the wind. So, I need this minimum angle uh to keep the airflow so that uh you see, I have this aerodynamic force. So, how do I get there? It's very easy. I have to do this fancy maneuver, uh which is called a tack. So, basically, I'm going to change the side of the wind. So, I'm going to push the rudder here.

[00:02:54]I'm going on the other side.

[00:02:59]Now, the wind is coming from this direction.

[00:03:03]You see? My indicator.

[00:03:05]And I'm just sailing now on the other tack. So, basically, to get up there, I'm going to have to zigzag zigzag uh you see, until I get there. Now, I can do this tack maneuver every minute, every 10 minutes. I don't want to do it every 10 seconds, right? But, uh Oh, there's a boat coming.

[00:03:25]I hope this guy doesn't want to crash me.

[00:03:28]Oh, you see?

[00:03:30]I have the right of way.

[00:03:32]That wasn't nice.

[00:03:39]So, let's do another tack just to show you. So, I change the direction.

[00:03:43]Almost got run over that boat.

[00:03:48]See, the sail goes on the other side.

[00:03:50]Now, my wind is going to be like this.

[00:03:54]And I'm sailing on the other tack. So, basically, I'm just going to zigzag until I get upwind where I wanted to go.