HOW or WHY does this work Vibrating Build a Sea Scooter at home 2 days ago   08:55

HOW or WHY does this work? Vibrating Boat propulsion 🚤🚢 PART 3. The aluminium hull split probably from vibration fatigue so I made a foam hull and had another go. We can clearly see there is a resonant frequency that gives us forward motion and higher or lower frequencies don't.

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Comments 22 Comments

Ken Heinrich
It looks like you are find the natural resonant frequency of the boat. As you approach the frequency ripples start to appear in the water and then the boat starts to move. It will vibrate when it's natural resonant frequency is reached.
Phantom Exploration
it’s a good example of resonance frequency’s.
Hermit Oldguy
Waves on the surface of water
Hermit Oldguy
I wonder what happens if you put a pendulum on a boat hull, so it swings along the centre-line (keel).
Mike Flight
Yes, I think you cracked it. As you say, it is the harmonic or frequency that reaches the correct point and makes it go forward. The question I would ask is, why does it go forward?
On the aluminum boat, I thought it because of the split in the foil but this proves that it was something else. Great experiment. :D
Jag Betty
It seems similar to when you hit that sweet spot on a guitar and you get a nice harmonic. There’s only certain places on the guitar neck where you can get it.
Hermit Oldguy
My knowledge is radio waves (which move at the speed of light), so I can tell you about waves, but I don't know the speed of water (viscosity) so I can't guess the right frequencies.
Your sink has length and width - say 40cm and 30cm so they are the fundamental wavelengths. Your boat also has length and width - say 20cm and 10cm.
Now you can intuitively sense that something interesting would happen in 10cm long waves. The sink would be 4 wavelengths by 3 wavelengths and the boat 2 wavelengths by 1 wavelength. I don't think the boat would travel, but it would bounce about a lot. To get it to travel, you'd prolly need it to be a bit different length - create a mismatch between the water and the boat.

I think the weight on your motor needs to be moving more slowly, only up and down, and through a longer distance - a much lower frequency and greater amplitude.

The strings on my guitar are about 65cm. The 40cm mark is about the 8th fret, so if I barre at that fret (and if it's in tune - unlikely), I'd get the fundamental waves called C, F, A#, D#, G, C.
If the relationship was length of string to speed of sound, I think they'd all sound the same, so I guess the relationship must be length of sound to speed of string (elasticity?)?
Max Xiang
Try putting the motor on sideways
Aadil Shah
We might need someone with a slow-mo camera to see why the harmonic.
Looks like the aluminum moved a lot more and so moved more water, like the diaphragm in a carburetor. Combine a flexible diaphragm with a more rigid piece to add pressure to the water and you'll be off like a jet
Convex chart 49
Wow you did great on your boat I want to try this
Joey the bmx kid
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Build a Sea Scooter at home HOW or WHY does this work Vibrating 2 days ago   20:59

How to make a Sea Scooter at home.
Warning : If you do not know how to swim, never do make it
Thanks for watching, Have a great day !