What would happen if ? ? ? Car horn under water.

Thread Starter

Tonyr1084

Joined Sep 24, 2015
4,737
This morning I had a strange dream. Often in dreams we have - we are a part of what's going on. In this one, and I'm not going to recount the whole thing, it was more like watching a movie. The particular standout in the dream is a woman who was upset with her husband because he took longer than usual to come home. His excuse was that he drove the car into the lake. He said no one could hear the car horn. So his wife drove her car into the pool to do an experiment - to see if anyone could hear her blowing the horn under water.

So this is my ponderence: What would happen if you put a car horn in a bucket of water and then blew it? Wouldn't the tone change? Would it be louder or quieter? And if your hand is in the water when you blow the horn; would there be a shock?
 

DickCappels

Joined Aug 21, 2008
6,463
Yep. That makes sense.

The horn might sound very loud under water but the sound might not couple well to the air.

Pitch might increase since sound travels faster in water than in air.
 

AlbertHall

Joined Jun 4, 2014
10,068
The answer might depend on how the particular works. Commonly it is electromechanical working a diaphragm. If the water can get to the diaphroagm then it would have to move a much larger mass of water compared to when it was in air. This might also interfere with the diaphragm movement operating the contact which connects/disconnects power from the electromagnet.

[EDIT] That would have given my English master a lot of uses for his red pen!
 
Last edited:

narkeleptk

Joined Mar 11, 2019
465
Soon as half the cars electronics and battery where submerged, I doubt anything non mechanical would work at all. I imagine the guy in your dream was right. No one could hear the horn because it wasn't even blowing.
 

nsaspook

Joined Aug 27, 2009
7,356
Soon as half the cars electronics and battery where submerged, I doubt anything non mechanical would work at all. I imagine the guy in your dream was right. No one could hear the horn because it wasn't even blowing.
It depends on how clean the water is and if the battery was an AGM type. I've had electronics covered in ultra-pure DI water operating perfectly for hours.
 

narkeleptk

Joined Mar 11, 2019
465
It depends on how clean the water is and if the battery was an AGM type. I've had electronics covered in ultra-pure DI water operating perfectly for hours.
I helped a client not long ago on a repair for a express van. His customer had power washed the rubber floor mats through out the van. Long story short, he ended up filling the airbag module up with water (installed under the rubber mat near a seam). The truck would barley run and there where a lot of bizarre issues with low voltages and communication problems, including no horn.

I work on a lot of flooded cars and power washed modules in general. Unless they are sealed or have decent conformal coating on them they usually do not fair well .I've seen some fuse boxes where it looks like a bomb went off inside just from people power washing the engine bays.

This one is a bit tame sorry I did not have time to go digging through my photo's for some of the bad ones, but this a typical example from a Wranglers TIPM(fuse box) after a brief power wash of engine bay:
wrangler-tipm.jpg
 
Last edited:

SLK001

Joined Nov 29, 2011
1,548
The horn might sound very loud under water but the sound might not couple well to the air.

Pitch might increase since sound travels faster in water than in air.
The speed of the sound will be faster, but if anything, the pitch will decrease due to the need to move a larger mass with a vibrating membrane.

I don't want to know what Tony had to eat the night before - I'm more interested in what he smoked!
 

Thread Starter

Tonyr1084

Joined Sep 24, 2015
4,737
Anyone got a sacrificial horn to test the theory?
I have a few at home. But I'm not at home to test this strange idea. I admit it's rather strange thing to come up with. But a good sealed horn, the kind with the spiral tube should provide decent protection from water infiltration. The European style horns have the diaphragm right up front, so that should have a different effect.

I doubt anything non mechanical would work at all.
I've seen plenty of motors run under water. I've run a few submerged in a tub of clean water. And yes, I know that clean water is close to an insulator but dirty water can be very conductive. Which is why I wondered about submerging a horn in a bucket and holding it there while blasting it might introduce high voltage pulses to the water. Hence, my question about getting a shock.

If I remember this post by the time I get home I will be eager to try it. The horns I have are basic two wire horns with the diaphragms either buried behind a spiral tube or right up front. But that won't be for a number of days.

Gotta go now. Hotel is serving breakfast. Hope it's pizza.

@SLK001 Haven't smoked since 1982. And rarely in the presence of anyone else smoking. And at that - smoking was the worst of my experimentations with mind altering agents. Other than an occasional bottle of Updaug.
 

narkeleptk

Joined Mar 11, 2019
465
Electric motors you mean probably?. I have only been considering if a car is submerged. As far as auto's go maybe diesels could run briefly while submerged under water but no way a gas engine will. They need 3 things, Spark, Fuel and AIR. Good luck getting any of those when submerged with out heavy modification. I imagine they stall pretty much immediately when they go under from air being cut off..
 
Last edited:

crutschow

Joined Mar 14, 2008
25,133
I believe a typical car horn has a diaphragm this resonates in air at the desired frequency.
If water contacts the diaphragm then it would not be resonant or, at best, would have a much lower resonant frequency.
 

Glenn Holland

Joined Dec 26, 2014
705
The impedance of water doesn't match the horn diaphragm so there wouldn't be much oscillation. Here's another thought experiment about acoustic physics. Can you make an organ pipe play under water by connecting it to a hose?
 

shortbus

Joined Sep 30, 2009
7,768
As far as auto's go maybe diesels could run briefly while submerged under water but no way a gas engine will.
Are you saying a diesel doesn't need air to run? Since a diesel doesn't use a "butterfly" in it's intake tract, I think it would run a shorter amount of time, before hydraulically locking up. :)
 

narkeleptk

Joined Mar 11, 2019
465
Thanks, I am sure your right. I only assumed since I do not have much experience (other then driving one everyday :eek: ..... luckily haven't needed to work on it yet.) with diesels engines it would fair a little better.

That reminds me tho about 20 years ago in my young teens a buddy of mine pulled up in his busted up 190D but it would not cut off. I believe the term is "Run away Diesel" We had no idea what to do. Tried yanking fuses and relays. Then at the advice of another one of his fool friends he even cut the fuel line. She just kept on going. We finally got a little sense in us, then blocked the intake and It finally stuttered out.
 

Thread Starter

Tonyr1084

Joined Sep 24, 2015
4,737
Electric motors you mean probably?
Yes. Electric motors. I know that an electric car window can be rolled down even after being submerged. I doubt the DVD will play. OR the CD player, or the dash board readout. Electronic things can be very sensitive to stray conductive paths. However, the Davis Applied Technology College had an open house. On display was a working computer under ultra clean water. The water tank it was in had hoses carrying away the warmer water and expelling the heat through a radiator, then pumped back into the tank. I doubt a car's computer will still function after being submerged in a lake.

I'm confident a car horn will work both under water and in air after being pulled out of the water. Just the two things I wonder about is whether the horn will be louder under water or if the pitch will change (Probably) or if the horn is blowing under water and you stick your hand in the water while it is blowing, if you'll get a shock. Like taking a small transformer and touching the primary or secondary leads and touch them to a D cell battery. Upon disconnecting I DO KNOW you get a hell of a kick.
 

narkeleptk

Joined Mar 11, 2019
465
I know that an electric car window can be rolled down even after being submerged.
I always heard the water pressure makes it extremely difficult to roll down or kick the windows out. and that if you ever where to crash in a lake or pond you should immediately try to open your windows before going under completely so the pressure could equalize inside the cabin and you could then open the door easier to escape if/once the cabin filled completely with water.
 

Thread Starter

Tonyr1084

Joined Sep 24, 2015
4,737
I believe a typical car horn has a diaphragm this resonates in air at the desired frequency.
If water contacts the diaphragm then it would not be resonant or, at best, would have a much lower resonant frequency.
I bet there would be some cavitation that would allow the diaphragm to stay closer to its original resonant frequency.

It's going to be a while before I can get home and test this out. So if someone wants to volunteer to toss the two different types of horns in a bucket of water from the garden hose - go ahead. Let us know what happens. And please don't stick your hand in the water while blowing the horn. I suspect you'll get a shock. Since it's my idea I'll be the guinea pig.
 

Thread Starter

Tonyr1084

Joined Sep 24, 2015
4,737
@narkeleptk the pressure agains the door makes it nearly impossible to open. However, rolling the window down may take a little effort but an electric window "should" be able to be rolled down after being submerged. From things I've seen on TV about being in a sinking car, some say to roll the window down as soon as possible, others say to wait till the car is nearly completely flooded and you are able to take one last gasp of air before rolling it down. IMO if you roll the window down while sinking the rushing water could make it difficult to gasp at that last breath of air. Plus, the inrushing water would make it impossible to get out. You'd have to sit there and wait for the cabin to fill with water. Of course, opening the window after the car is nearly completely full will make opening the window much easier and getting out much quicker due to less water rushing in.

They make emergency tools for cutting the seatbelt and for smashing the window. That, too, has been recommended to be in your arsenal of emergency tools, should you ever find yourself in the drink.
 
Top