When I'd read these comics as a kid, I'd wonder how Johann and Peewit managed to hide so deep underwater and breathe with just a reed.
I know that when I'm using a snorkel, I always stay close to the surface.
So that means that they would go much deeper underwater, which segues on to the question of the day:
How deep underwater can one go using a snorkel?
"I'd say about 1 meter deep." (3.8 feet)
"1,50 meters!"
"2 meters"
"I'd say over 20 meters."
"About 100 meters?"
Alright, let's try it out!
First problem: our diaphragm, the muscle that's at the bottom of our rib cage and which works our breathing.
When it tenses, it creates a depression inside the rib cage, which allows us to breathe in - you can see the pretend lung inflate here.
Likewise, when the diaphragm relaxes, our lungs empty themselves out of air: we breathe out.
On Earth, the pressure is of 1 atmosphere. 10 meters deep underwater, it's already twice as much.
In this experiment, we won't be going that deep, mostly because my snorkel is only 3.37m long, but it should be enough to have some interesting results.
We'll be measuring the distance between the diaphragm and the surface of the water.
It should be pretty easy to breathe out, since the water will be pushing on my rib cage. Breathing in should be a tad harder.
Our goal here is to get underwater, to draw at least one breath, then go deeper and repeat the process until we need to get back to the surface.
Oops, I lack organisation here and my snorkel gets all messed up...
Another snag comes up soon enough:
The plastic part of the snorkel is too flexible and crams itself in under the pressure of the water.
Our solution: to use the other side of the snorkel, which is much sturdier.
That's better... but breathing underwater makes us float on the surface.
We manage to cancel that out by having one person press down on the shoulders of the diver.
There's one last problem I couldn't quite shake off: fear...
Using this snorkel, I could feel my ability to breathe go weaker by the centimeter, and I didn't dare push my limits.
Now, let's hear the results!
We did 9 tries. The distances we've measured between the diaphragm and the surface of the water are between 70 and 140 cm.
The measure we got the most was around 120 to 130 cm.
Our average is 1.1 meter (3.6 feet).
Keep in mind that this value includes the dives we took and stopped before reaching our physical limits, and the dives when the snorkel was curved, which adds a little length to the value we measure.
Still, we've got some useful information: our answer lies around 1 meter deep.
That was a fun experiment, but I have another, more reliable and easier one to try at home with the help of a nanometer.
We have a long tube, open on both ends. We're simply going to draw a breath from it.
The water inside the tube will help us measure the difference in height we can make, which is linked to the depression that our respiratory system can make.
Although I had reached (a very impressive) 70 cm underwater, here, my breathing ability reaches up to a difference of 120 cm.
Manuel, who had reached 140 cm deep underwater, now manages to reach a good 180 cm.
We thus have an average of 1.5m (2 values aren't much for an average, but they'll have to do!).
Supposing that the density of the water of the lake is the same as that of my tap water, we find a difference of around 35%.
This illustrates how much the setting influences our performances. On Earth, there's only one breath to take, we can quit the experiment whenever we like.
But underwater, we first have to go back to the surface and take several breaths, adding to that a depleted air.
That's another problem I hadn't spoken about with our long snorkel: the air we breathe.
In average, a person who weighs 70 kg breathes in and out 700 cm^3 per breath. My 3.37-meter-long snorkel has a volume of 700 cm^3.
So basically, when we take a breath with the snorkel, we breathe in the air that we have just breathed out.
Not only will we have drawn out all the molecules of oxygen in just a few breaths, but we'll also render the air inside the snorkel toxic what with all the CO2 we breathe out... ergh!
There's a very simple solution to this problem, though: to breathe in through the mouth and breathe out through the nose.
Let's sum it up: the pressure water puts on our diaphragm makes it hard for us to breathe, so we can go about 1 meter deep in real-life conditions.
That's about 111,135 Pa = 1.1 atm.
That may seem very little when you know that our earthly environment is at 1 atm, but it's actually like having to breathe with me sitting on your diaphragm!
Our diaphragms aren't that strong, but then again, this situation doesn't come up very often.
If you'd like to know more about the topic, I advise you to read 2 highly scientific references:
Spirou et Fantasio: Le Repère de la Murène, and The Adventures of Tintin: Red Rackham's Treasure.
I was inspired to make this video by Prof. Walter Lewin's class (link in the dooblidoo), which I saw months ago and promised myself I'd try it out.
Lewin did the theoretical part of the research, plus the experiment with the nanometer, which you saw me do as well.
While doing this experiment, I was faced with numerous problems, as you could tell - and many more probably remain untold -, but this is what I want to do with this YouTube channel:
to take something for which we have a nice, working theory, and then put it to the test in real-life conditions.
I hope you liked this video, because I really enjoyed making it! See you soon.
I'll let you click on this greedy little squirrel to subscribe! ;)