Sailing Faster Than The Wind - How Is That Even Possible?

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The alternative explanation goes something like this (I'm simplifying!) - Lift is generated when air is moving relative the sail. As the boat speeds up, the relative speed of the air should increase and so the lift should increase! This explanation doesn't work for when you're sailing somewhat with the wind though. In that scenario, as the boat begins to speed up, the relative speed of the wind actually goes down.

Delighted that I can wave my hands and a Steve Mould video appears

”I am the wind” —Steve Mould 2021

"Let's assume it worked perfectly"
- Oh, yes, physics

Just as an aside, in practice sailors can rely on tactile and visual feedback to "feel" their way to approximately optimal angles. It quickly becomes largely intuitive, like learning to riding a bike.

Forms of this feedback include the relative direction of small weather vanes, boat tilt or the sail floppiness.

I feel like that’s not the only framed photo of Steve he owns

Solid collaboration. Funny that I sign up for a sailing class this summer, and boom, Steve Mould makes a video about sailing. The universe is calling mate.

Me: "Why do you even own a framed picture of Steve, Matt?"
*Looks at the picture"
Also me: "Holy shit, that is one handsome Steve"

One is experiencing the same when inline/ice skating. You are moving much faster forward than your foot moves outwards.

Not sure if I missed this in the video, but need to also consider that Derek was using a wind turbine as a sail. A turbine can act like a flywheel, storing energy. A good question to ask is “what happens when the wind stops?”. A sail boat will no longer generate lift, but the inertia of the boat will keep it going. A wind turbine however will continue rotating and continue providing lift, so it’s possible to build more speed thanks to the energy storage element. At least, that’s my assumption, haven’t thought all that hard about it.

Friggin awesome explanation and congrats on 1 million subscribers! I can tell which parts you filmed before and after lunch from the stain on your shirt :P

For anyone wondering, there is also the really fun phenomenon of generating your own wind. Which occurs because as you gain speed, you are now experiencing wind equal to your speed(essentially) in the opposite direction of your travel. So as you speed up, you start having more wind, in a more bow(front of boat) position. So you can then capitalize on that and go faster, which is why many sailboats nowadays are optimized for more upwind sailing. The most dramatic example I have seen was America's Cup World series boats(which has all sorts of optimizations like wings and foils) and traveling downwind, they had their sails in close as if they were going upwind, and their windex's read that the wind was about 4x faster than we experienced elsewhere. Really good video, thank you for making. I did not know about the whole missing thing with the wind, and you could certainly make a hundred videos about the physics of sailing.

Congrats on the 1 million subs Steve. I love this channel, I hope it continues to grow.

7:08 this is why in sailing, changing the angle of the sail is similar to changing to a higher gear in a car. you start at a steep angle because that gives the most perpendicular force, but after accellerating for a bit you reach the maximum speed for that angle and have to pull the sail into a shallower angle to get any more speed. until you reach the maximum speed the boat is capable of when the sail is almost perpendicular to the wind.

so the best angle for the sail depends on where the boat is pointing, where the wind is coming from, the speed of the wind AND the speed of the boat.

I don't say this lightly, but this might be my favourite video of yours. Something complicated and counter-intuitive explained with such elegance and ease that I'm half convinced that its entirely obvious and I always knew it. Worthy of being the first one after the million barrier

Steve, to me you are like the mid life dad who started documenting random experiments in his back yard out of curiosity for how things work. Really enjoy watching you explore and explain stuff you learned.

I was wondering how the NZ land yacht broke the land speed record recently by doing 222kmh with only 40.7kmh winds.

Actually, the boat moves away from Steve Mould due to the awkward encounter they had at the Christmas party last year.

Bernoulli's Principle and the Coanda Effect are two sides of the same coin as I understand it. The Coanda Effect describes how flow clings to a convex surface resulting in a change in the flow's direction of travel, and Bernoulli's Principle describes how the force required to change that direction of travel is reacted against the curved surface via a change in pressure. You don't get one without the other.

4:27 The blue/sideways force does have an affect! Because it and the ‚resisting force on the hull‘ are offset, the boat gets tilted. Thats why big boats have weights in the keel and small boats relie on the bodyweight of the sailors to counteract it.