Hi, i am baking a arduino-boat, and it would like to mesure the depth under my boat, with a really max depth of 2m. i wanted to put it in a small waterproof box, but il will probably stop the sound and give a distance of 0cm. do you think if it could work if i write my own function with experimentals values? or most of the sound will be stoped by my box, and i wouldnt be able to measure anything?
Any ideas?
thanks for giving tips!
I think the coupling to the water will be very poor, and you'd have to adjust for the faster speed of sound in water.
I very much doubt you'd get anything like two metre range.
and do you have any other ideas for a cheap sensor wich could do it?
I thought about ir but they have small range...
Fishfinder transducer?
It's a pity the operating frequency doesn't match, or you could try unsoldering the transducer from an air sonar unit, and replacing it with a water one.
Hi, I was thinking about a similar project, using the sensor as it is wont work for sure. (or 99%) my plan was to create a custom sonar sensor using the famous piezzo drum discs, but it require some additional circuits and complicated signal processing so i have dropped the idea for now. what is may be possible but havent got to it yet and probably not in the close future, is to disamble the hc-sr04 sensor and use its board and actuators separately. sinking the transmitter/receiver as they are underwater (will be damaged by corosion but as long as it is not sea water shouldn't short circuit).
another option is just to buy a waterproof sonar seen one on ebay for 15$
anyway take in count that underwater the speed of sound is different and has different decay, so results will differ (don`t remember numbers).
hope you will have some results to share 
good luck.
Hi, i really doesnt need great precision, so it can be a little bit homemade! And for the sound spped underwater i think you can make some ties and just rescaled your values when you have build something. I think that just put HC-SR04 like that underwater will destroy it really really quickly.
But maybe a simple varnish layer will be enough to make it waterproof without stopping that much the sound!
can anyone suggest an under water sonar(depth measurement ) sensor that can be used with adrino
Same requirement but I dont think there exits a one for hobbyists (yet?) if there are no updates over past few years?