Kind: captions
Language: en
So, my question to you is uh uh let's
say the wind is coming from over there.
I want you to position the boat in
whatever direction you think will make
it go the fastest. And how would you set
it up?
And then you can you can set the sail
how you want. Something like that.
This way. Which
you want to point the boat this way.
What would you want to do?
So, how do most people think a sailboat
works? What would you say?
Most people think a sailboat gets some
wind and manages to move. They don't
really know. Or maybe that that like
gets pushed from behind.
Yeah, the pushing by behind is is um
somewhat easy to visualize.
Your fastest direction would be
uh straight forward.
Would be going with the wind.
Yeah, with the wind.
I want you to talk to me about what the
wind is doing to the boat here to make
it go forwards.
Well, with the wind behind it will push
into the sail.
Pushes against the sail.
Just go left
and it pushes the sailboat forward. So,
the slowest way to position your boat is
well, the slowest is straight into the
winds because you're not generating any
lift
and the second slowest like the slowest
actually sailing.
Ah, it would probably be close to dead
away because you're very limited to
So, the wind's coming from the back and
you just got your sails full out.
Yeah. Because when you're going directly
away from the wind,
your boat wind cancels out the actual
wind.
So, you can actually never exceed it.
You would only be able to match and you
would have nothing, no force in your
sails. But that would only But that
would be frictionless too, which
couldn't happen. [laughter]
Could you sail upwind?
Probably with difficulty
very slowly.
That's doing this a little zigzag.
How does it go forwards if the wind is
coming from here?
How do you get it?
You'd have to bring it right round like
that to bring it to the side and then
flick it right back round
to bring it in against the wind as you
go. But that's how I've seen the boats
go. So, I'm trying to figure out what
could make the boat go forwards if the
wind's coming from that side. You know
what I mean?
An engine.
Which way is the force on these sails?
What do you think?
Uh, I think it tends to be a little
little back and sidewards.
So, the forces back and sidewards. How
does the boat go forwards?
Yeah, it's okay. But then, well, again,
[laughter]
well, I know I know it does, but again,
I don't have all the answers.
So, how does a sailboat move?
The sails actually act like wings,
generating uh high and low pressure on
each side. You generate high pressure on
the inside of your sail and low pressure
on the outside.
So, you going faster around the outside,
right? has a longer way to travel in a
sense, right?
Okay.
And then um you generate a bit of lift.
So the lift will actually end up being
in kind of this direction towards me
which is mostly sideways and a little
bit.
It is mostly sideways and a little bit
forwards. But that's why we need to have
the center board and rudder and they do
they kind of counteract that force
because they generate high and low
pressure as well as the boat's trying to
be pushed sideways and kind of balances
it out so the boat goes forwards.
Okay. But it seems like I mean if the
there's a force pushing that way on the
sail and the opposite way
on the centerboard it seems like the
whole thing would tend to
it would absolutely try and turn over
and which is why the body weight and the
leverage of the people is so important.
How can a sailboat go faster than the
wind?
[laughter]
Because it can generate
it can generate
more pressure by its motion.
Okay.
Right. Like it's there's only
it can actually happen quite easily in
light wind because let's say you only
have three knots going this way and then
you generate a knot of motion. Well, all
of a sudden you're sailing with more
than three knots of breeze over your
sails and then it can build and compound
on itself. The limiting factor is the
drag on the hull.
I see. Okay.
Yeah. Yeah. Yeah.
So, and the drag on the sails actually
that's actually very large as well.
So, in fact, the fastest way to sail a
boat is is not downwind. It's actually
kind of uh like 90 degrees or 45 degrees
to the wind, something like that. That
that makes the boat go faster.
Okay. Thank you very much.
You're very welcome.
I hope you enjoyed this video on the
physics of sailing. If you want to see
more with Hunter, click the first link.
If you want to see more about how a wing
generates lift, click the second link.
And if you haven't subscribed to
Veritasium yet, then click the third
link. And I'll see you next time.
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Heat. Heat.
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