How Does a Boat Sail Faster Than The Wind?!?!?

How is it even possible for a boat to sail faster than the wind, let alone 2-3 times faster, like this AC72s of the 34th America’s Cup? That’s exactly what we’re going to find out in this video.

Early sailing ships looked like this, and pretty much used their sails as big parachute like drag devices to pull themselves along in the same direction as the wind.

This isn’t very efficient and it’s also impossible for any boat like this to sail faster than the wind.
This is because as the boat accelerates the wind effectively disappears as boat catches up to it.

Instead, modern sailing boats work much more like airplanes which use their wings to generate lift. Except on a boat the wings are oriented vertically instead of horizontally. One wing is the sails in the air, and the other is the daggerboard or keel in the water, also called a foil which is short for hydrofoil. The foil produces just as much lift as the sail even though it’s much smaller, and that’s because water is 800 times denser than air.

Modern sails look much more like a streamlined airplane wing than a baggy parachute.

They also generates lift in the exact same way. As the wind flows over a modern sail from front to back, the sail generates lift perpendicular to the surface of the sail, just like an airplane wing.

Underwater foils like the keel on this monohull come in all shapes and sizes, but like the sails in the air they also generate lift perpendicular to their surface as the water flows over them from front to back.

Except unlike an airplane, where the wings both generate lift in the same direction to lift the plane off the ground, the sails and foils on a sailing boat generate lift in opposite directions, and this is what propels the boat forward.

The tighter the angle between the lift from the wind and water, the faster the boat will go. And the faster the boat goes, the more apparent wind it generates to flow over its sails, which generates more lift, which makes the boat go even faster. And this cycle will continue until the friction with the water prevents the boat from going any faster.

That’s why the fastest boats have underwater foils that provide lift in two directions – a horizontal side force to counteract the forces of the sails and drive the boat forward, and a vertical component to lift the boat out of the water and reduce friction.

None of this would be possible without high tech materials like carbon fibre, epoxy, and Dyneema, which can create structures stronger than steel at a fraction of the weight.

Disclaimer:
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- There are no warranties, expressed or implicit, about any content or its fitness for a particular purpose.
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#howto #sailing #howtosail #learntosail #sailingtips

[alexmijo]

Incredible physics analogy with the two rods and the puck, most intuitive explanation I've ever seen of this

[GraveUypo]

thanks for not having a 8 minutes long black and white session about canoes before getting to the point

[ItsAVolcano]

Fun fact, old sailing boats used to put the worst smelling facilities at the front of the ship, since the wind would carry the smell forward and away from the ship.

[mil]

Finally a channel that asks for a like at the end, not the start. Great video. 🎉

[bobbobby]

I'm not into boats but I am into knowing things. This video was randomly recommended and it was very concise and easy to understand!

How does the boat start and maintain movement tho??

[lightbox]

as a young (16 year old) guy, I sailed a Comet with my younger brother on Lake Hopatcong in NJ, if we had a 6 mph breeze against out main sail and jib, we could easily reach 10 to 15 mph depending on hard we haled the mainsail close to the plane of the 22 ft boat Eventually, the 90 year old canvas mainsail exploded and we never had the resources to repair or replace it.

[davidbellamy]

Having down quite a bit of sailing when I was younger, I've been very curious about this. Thanks for a simple, clear explanation!

[martymodus]

Good example with the cap. On a side note, airplane also use multiple vectors of lift. Yes, the wings lift upwards, but also, lift from the propellers provides lift in the forward direction, although we then call it thrust. Still, the blades are still utilizing the Bernoulli effect with an airfoil shape to utilize high/low pressure differentials. Even jet engines require these differentials internally in order to provide the pressures necessary to initiate jet propulsion.

It's all about the pressure.

[GabbersLJ]

Brilliant, thank you. Ive been trying to understand these boats whilst watching sail gp and just couldnt figure it out. Clear and concsie!

[ChrisPBacon]

I thought Jordan Peterson was narrating this video 💀

[little-pwnie]

This was a very well made video. Thank you for being so clear and concise and not making a 10+ mins video 👍

[dashman]

Very interesting. The Yacht is effectively being squeeze between the wind and the water. Amazing.

[christians]

Thank you, excellent description and visualization. I learned a lot

[amac]

had a 18 foot maricat when i was a teenager. nothing to do with this video but mate was it one of best feelings to get it up on one side and ride the wind.

[SukacitaYeremia]

I now understand a little bit more about what hydrofoils and dynamic keels do under water, and how it balances the sailboat to prevent it from keeling over and how it might drag, stall, or fail if sudden changes are applied to it.
As a SailGP enthusiast, I'm grateful

[harrykreia]

We call it creating your own wind (on low drag boats), thats why the appearent wind always comes from the front(and way stronger then the real one), even on reach or broad reach, but you cant do it downwind. You have to reach and jibe downwind.

[GentleTaipan]

Excellent demonstration 👏 forwarding this to a physics teacher

[omundocomjanio]

Great explanation! I just watched a race video and was wondering why they just had one foil in the water. Your video answered that question too.

[_Davepocalypse]

So well explained and visually represented!

[aguysaid]

Puck description is spot on well done Sir!