Most surfers simply accept the fact that

we paddle into a wave, stand up, and ride it

without ever really questioning what's making this happen

or what's going on beneath our feet.

Perhaps when we're shopping for a new surfboard,

we might think about the effects of variables

such as length, width, volume, bottom contours or tail shape

but for the most part, the majority of us are blissfully ignorant.

Even a lot of surfboard shapers, although they'd never admit it,

aren't that wise as to the physics at play

when the surfboards they've shaped are being ridden.

They know what works and that's what they continue making.

A big reason for this is the lack of proper research

that has been done on surfboards.

A lot of what we know about surfboards

has been worked out through trial and error,

and while a few people have hypothesized the science

behind why a board performs the way it does,

there is little hard evidence to support these claims.

We are going to address some of the core mechanics here and now,

and then build on them in future episodes that

will refer back to the points and principles covered here.

Let's start with speed.

it's what we're really after when we're riding a wave,

not just because it gives us a thrill,

but also because it's the raw material for producing good maneuvers.

Where does that speed come from and how do we generate more?

If you answered gravity then you're partly correct.

When you paddle into a wave and drop down the face of it,

it is gravity that's pulling you down and causing you to accelerate,

and even when you angle across the wave,

gravity is still helping to generate some of your speed.

However, if gravity was the sole factor in generating speed,

you should go fastest when going straight into the beach.

But that's not the case. Your board actually travels far faster

when traveling in trim across the face of the wave,

and this is all to do with how the flow of water

on the wave face interacts with your surfboard.

The very first thing that we need to get clear here is that

when we look at an unbroken wave,

it is mostly wave energy that's moving, not the water.

If you placed a rubber duck on the surface of the ocean

and watched a wave pass,

the rubber duck would just rise and fall as the wave passed underneath.

It wouldn't be picked up and carried by the wave.

A good way to think of it is to imagine a blue tarpaulin,

and then roll a bowling ball underneath it.

You would see the wave of the bowling ball

moving under the tarp, but the actual tarp itself remains in the same place

However, if we were to follow the bowling ball with a camera,

we would see the canvas rush past, and the same is true with an ocean wave.

This creates what we call an effective flow of water running up the wave face

from the perspective of the surfer.

When we take off on a wave and set our rail to start riding across the face,

our surfboard interrupts the apparent flow of water.

Two things then happen: our surfboard grips the face of the wave and

the surfboard generates lift and forward thrust.

Depending on exactly how the board interacts with the water flow,

the amount of lift, thrust, and grip can be varied to suit

the maneuvers we're trying to do on the wave.

In the next episode, we're going to talk about the physics involved in this process.

So until then, thanks for watching.