Diving With Active Sonar, what is safe?

Please register or login

Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

Benefits of registering include

  • Ability to post and comment on topics and discussions.
  • A Free photo gallery to share your dive photos with the world.
  • You can make this box go away

Joining is quick and easy. Log in or Register now!

coleusna2006

Registered
Messages
14
Reaction score
2
Location
Falmouth, MA
# of dives
I just don't log dives
I am in the planning phase for diving with an active source, specifically a series of underwater robots that track each other. I would like to be in the water with them to observe their actions but I want to mitigate as much risk as possible. The robots’ sonar transmits in the 17-34 kHz range with a maximum source power of 65W. I am looking for information regarding what SPL is safe for divers in the 17-34 kHz range. My intention is to calculate the range from the robots that is safe and to ensure that I maintain that distance from the robots while they are in a mode that could result in them transmitting. Any tables, articles, links or other relevant information would be much appreciated. Thank you for your help!
 
Check down the street with the folks at Woods Hole. Lee Freitag and Darlene Ketten might be a good start.
 
I am in the planning phase for diving with an active source, specifically a series of underwater robots that track each other. I would like to be in the water with them to observe their actions but I want to mitigate as much risk as possible. The robots’ sonar transmits in the 17-34 kHz range with a maximum source power of 65W. I am looking for information regarding what SPL is safe for divers in the 17-34 kHz range. My intention is to calculate the range from the robots that is safe and to ensure that I maintain that distance from the robots while they are in a mode that could result in them transmitting. Any tables, articles, links or other relevant information would be much appreciated. Thank you for your help!

Get in the water you are safe Ive been inthe watger with well over 200 db. . the 65 you are talking about is high freq and not the 1-4khz range that jiggle s your tissues to jello as some claim to happen. . Also the spl you are referring to is measured 1 yd from the source Probably what you have is equal to a fish finder or fathometer. Next 65 watts is less than a lot of car stereos and above the normal hearing range to boot. Next high frequencies do not propogate in the water very well. 65 watts of 1kh is nowhere the same as the tiny 65 watts of 25khz. Water does not like to vibrate at those higher freq's higher freqs need a lot of power to go through the water. At higher freq's if it were to ping every one second you would hear nothing but a repeating thud or click as opposed to a short tones.

DBF's comments apply as well.
 
Thank you for all the comments. I did the calculations with a sound level of 167dB, assuming spherical spreading, which is likely not a great assumption as it is shallow water, with the vehicle and the divers close to the bottom so there will be multi-path arrival.

Assuming no acoustic protection from the hood:
Safe diver range = >12.4m which is too far
Max power for a diver to be safe at 1m = 0.42W

Assuming 10dB protection for a hood (likely not a good assumption in this frequency range)
Safe diver range = 3.92m, which is possible but not ideal
Max power for a diver to be safe at 1m = 4.22w.

I think that the best bet is to turn down the power of the transmitter. I am not sure how this will work for the actual experiment but at least it will keep the divers safe. If needs be will run it with low power, verify the behavior of the vehicles, then if needed, pull divers from the water and raise the power of the transmitter for follow on tests.
 
How are you converting your 65W source power to pressure?
 

Back
Top Bottom