

New research discovers how to perform the perfect cannonball

Students at Georgia Tech University have been working on questions around fluid dynamics providing insights for the swimming season along the way. Turns out, the world’s splashiest pool jump can be found halfway around the world.
It’s nice when the word cannonball is used outside of any warfare context. All we care about here is this: sitting, bent or stretched? Generations of teenagers have endlessly debated which jump into the swimming pool conjures the highest water spout to reliably splash onto the lawn meant for sunbathing. Followed by trying it out in the public diving pool, of course. Up, down, splash. Up, down, ouch! Repeat.
While multiple somersaults aren’t an option for most due to a lack of practice, the cannonball is the easiest way to get maximum attention. But how do you craft the most impressive water jet?
Manu above all others
This question has come up because some of those youngsters from back in the day have long since become students. Research doesn’t stop at leisure, of course. After some young academics at Georgia Tech University had finished dealing with questions of fluid dynamics in the animal kingdom, their lecturer brought the search for the perfect splash into play as a side project. They had to head far down south for an answer. To New Zealand.

Source: Georgia Tech College of Engineering
There, Manu is more than just a jump that gets any bystanders wet. It’s part of Māori culture, one with a deep connection to water. They do everything right as a result. To perform Manu, a jumper dives in buttocks first, while the body forms a kind of V at a 45-degree angle. «How they hit the water is less crucial than what they do immediately afterward,» says Daehyun Choi, one of the lead authors of the recently published study.
The secret is revealed under water
The more complex movement involves the body being quickly stretched, drawing down a large air bubble, which then produces a powerful jet of water. The students investigated the importance of timing using Manubot, a v-shaped, 3D-printed device with a hinge that could open and unfold under water. If this happened too early, there was only a small jet. The trick is to dynamically shoot your head downwards and stretch your legs upwards right after entering the water.
It’s an art that no one has mastered as well as the Māori, and nowhere is it more firmly established than in New Zealand. There, it’s both a fun pastime and performed at events such as the Z Manu World Champs. This year’s winner Maara Toa shot a record jet a good ten metres into the sky – twice his jump height. The Manu makes it possible. If you want to try it out, please look for a sufficiently deep pool. This German-language book might help in that regard:



Simple writer and dad of two who likes to be on the move, wading through everyday family life. Juggling several balls, I'll occasionally drop one. It could be a ball, or a remark. Or both.