I’ve recently made my first forays into surfing, and even though I didn’t perform particularly well (considering even my beginner’s status), I liked it a lot and would love to improve. This, combined with a general interest in physics, made me wonder what, exactly, the mechanics behind catching a wave are. My concocted layman’s guess is that catching a wave occurs when the surfer, paddling on the board, is moving at about the same speed as the wave in the moment the wave reaches him from behind. When that occurs, the surfer becomes locked in the phase of the wave and gets the energy needed to maintain that speed from the wave itself: If the wave is broken, he keeps being pushed forward by the white water behind him; if the wave is unbroken, he continuously slides down the slope of teh wave being pulled by gravity without ever reaching the bottom of the wave because as soon as he slides forward, the water underneath him rises as a result of the wave and opushes him upward again.
Is that, at least very roughly, correct? What follows from the physics of surfing for a surfer who wants to increase his chances of catching waves, rather than having the wave simply pass underneath him - is it just “paddle as fast as possible”, or is there more to it?
Although there are more nuances to how a surfer maintains position, your description is essentially correct; the surfer is continually falling into the wave, which is moving out in front of him. Note that while the wave (upraised water) is moving forward, the movement of the ocean itself is essentially only in the vertical direction except when you get to a breaker where it separates and behaves in a turbulent fashion, concentrating the wave energy into a small volume of water that is thrown forward.
Without being surfer (except body surfing and boogie-boarding) or a scientist, and without reading the OP, this was going to be my answer based solely on the title.
Think about how being able to be towed in by a jet ski has exploded big wave riding. It’s made catching big waves orders of magnitude easier. So yeah, paddling faster helps.
The other consideration is getting up. Getting up quick and being able to shift your weight forward to help the board fall down the slope helps you catch more waves.
You have to paddle fast enough that as the wave overtakes you from behind and the water under you steepens, you’ll accelerate “downhill” down the steepening hill quickly enough to get up to the wave’s forward speed before it passes you.
Which is why at the limit where you’re just floating stationary, you’ll feel a slight push towards shore as a wave passes, but little else. The wave’s shoreward speed is so much faster than yours that it passes you before it has a chance to accelerate you very much.
The monster offshore waves are traveling much faster than a person can paddle a board. Hence the jetski to get the surfer up to a speed that will couple with the passing wave.
Back for us ordinary surfers, the trick is simply that there’s a fairly short horizontal distance whereat the wave is steep enough but also unbroken enough to get aboard. And it travels shoreward faster than you can sustain paddling for very long.
So you need to get to the right spot, then time your sprint so you get up to speed just as the wave gets mature enough but not too mature and just as you and it are in the same place at the same time. Then once you’re hooked up it’s time to stand up. Easy peasy.
