It’s Back! Seismic Testing!

[tursiops]

I completely disagree. I don't have any hearing damage and I stand roughly 250-300 yrds away from the shot. Now if someone experienced 145 db closely...yes they would have 2 blown ear drums. Not only would they have blown ear drums but they would have bigger things to worry out in the means of the tidal wave that was created.

Are you talking in air or in water?

Sent from my SAMSUNG-SM-G900A using Tapatalk

 

[njdiver1]

I think you will find that the sky is not falling, and the hysteria you've shown in this thread is not going to help you get the info you'd like to have. Talk to LGL if you want answers, although I think you'll find that Appendix A is all you'll get.

Pending a conversation with the Marine Fisheries Bureau of our NJDEP, we will be communicating with an alumnus of Columbia University as to safe distances for recreational divers.

---------- Post added January 25th, 2015 at 10:03 PM ----------

Conversion of dB from air to water (and vice versa)

Based on the above discussion, it should now be obvious that 120 dB in air is not the same as 120 dB in water, primarily because of the differences in reference measurements. How do we make meaningful comparisons between a ship's engine underwater and a jet engine? In air, the sound pressure level is referenced to 20 µPa, while in water the sound pressure level is referenced to 1 µPa. Given the above equation for dB's, the conversion factor for dB air è water

​

dB = 20 log (p_water/1µPa) = 20 log (20) = + 26 dB

​

Therefore a pressure comparison between air and water differs by 26 dB. The characteristic impedance of water is about 3600 times that of air; the conversion factor for a sound intensity in air vs water is 63 dB.

​

10 log (3600) = 36 dB36+26 = 62 dB

​

A simplified example....If a jet engine is 140 dB re 20µPa @ 1m, then underwater this would be equivalent to

​

SIL_water = SIL_air + 62 = 202 dB re1µPa

​

To convert from water to air, simply subtract the 62 dB from the SL in water. A supertanker generating a 190 dB sound level would be roughly equivalent to a 127 dB sound in air. (Note that these are gross generalizations because the source level often changes with the frequency component of the sound.)

Underwater Acoustics - Navy Ships​

 

[Raider Drake]

Hello njdiver1,
and hello to others in this particular forum.
This is my first post here, so I apologize if the fonts are wrong, or something. I am very interested in reading this discussion about the possible impact of the sound produced by research vessel R/V Langseth on divers who might be near the area of that project planned for this summer.
I am not a diver, and I am not a research scientist, although I am fascinated with the science involved.

I would like to know the approximate location of any wrecks of interest to the diving community within the Langseth's research area or nearby (within 10 miles). From various internet sources, including posts on this board, I have found two wrecks. They are the Lillian (as mentioned in the current draft EA), and also the Maurice Tracy (which NJDIVER says was included in last year's EA, but doesn't appear here). Can you tell me where these 2 wrecks are, how deep they are from the surface-- and how often divers tend to go there?
I have written down these coordinates defining the space of the Langseth's projected work. I assume both these shipwrecks are within this area.

Langseth 2014/2015 targeted locations:
L1 39.3° N 73.2° W
L2 39.7° N 73.8° W

I write essentially with total ignorance on the technicalities of all this, and will be grateful for any clarifications of how this project affects the diving community that works and plays off of New Jersey's shore.

 

[njdiver1]

Hello njdiver1,
and hello to others in this particular forum.
This is my first post here, so I apologize if the fonts are wrong, or something. I am very interested in reading this discussion about the possible impact of the sound produced by research vessel R/V Langseth on divers who might be near the area of that project planned for this summer.
I am not a diver, and I am not a research scientist, although I am fascinated with the science involved.

I would like to know the approximate location of any wrecks of interest to the diving community within the Langseth's research area or nearby (within 10 miles). From various internet sources, including posts on this board, I have found two wrecks. They are the Lillian (as mentioned in the current draft EA), and also the Maurice Tracy (which NJDIVER says was included in last year's EA, but doesn't appear here). Can you tell me where these 2 wrecks are, how deep they are from the surface-- and how often divers tend to go there?
I have written down these coordinates defining the space of the Langseth's projected work. I assume both these shipwrecks are within this area.

Langseth 2014/2015 targeted locations:
L1 39.3° N 73.2° W
L2 39.7° N 73.8° W

I write essentially with total ignorance on the technicalities of all this, and will be grateful for any clarifications of how this project affects the diving community that works and plays off of New Jersey's shore.

The wreck of the Maurice Tracy is not located near the proposed survey's area. The wreck of the Lillian is directly within the proposed survey's path.

 

[Raider Drake]

Dear njdriver1,
Thank you very much for the clarification.
Are there any other wrecks or wrecksites in the vicinity of the R/V Langseth research, or are there locations of interest to New Jersey Divers that could be impacted by the Rutgers project in addition to the Lillian wreck site?
Also, since it seems that the Lillian might be the only major dive site, could you say roughly how deep the wreck is under the surface of the sea?
And also, how many groups go diving there and how frequently on an average summer? At issue is a general assumption of a "take" metaphorically speaking, of the recreational potential of the Atlantic as a result of this research.

 

[njdiver1]

Dear njdriver1,
Thank you very much for the clarification.
Are there any other wrecks or wrecksites in the vicinity of the R/V Langseth research, or are there locations of interest to New Jersey Divers that could be impacted by the Rutgers project in addition to the Lillian wreck site
?

I am personally not familiar with the area, there may be others. NOAA charts are known for inaccuracies when it comes to wrecks.

 

[Raider Drake]

Hi again njdiver1,
Thank you very much for your response explaining that you are not familiar with the area that is the subject of this specific discussion.
I thought, after all your posts calling attention (there are dozens), that you might have some special insight into the impact upon the NJ diving community by Rutgers' climate change research expedition.
I have written to a lot of people, and searched, and so far, the only significant site is that of the Lillian. But that wreck doesn't seem to be particularly popular among divers, relative to others; or have I misunderstood?
I had been caught by surprise about the Maurice Tracy when you posted about it, here. So I appreciate that clarification.

 

[njdiver1]

I thought, after all your posts calling attention (there are dozens), that you might have some special insight into the impact upon the NJ diving community by Rutgers' climate change research expedition.
I have written to a lot of people, and searched, and so far, the only significant site is that of the Lillian. But that wreck doesn't seem to be particularly popular among divers, relative to others; or have I misunderstood?
I had been, caught by surprise about the Maurice Tracy when you posted about it, here. So I appreciate that clarification.

My posts are not about the “why”. It is about keeping recreational divers safe who may be exposed to these surveys while diving. The available research on the effects of airguns on recreational divers is near non-existent.

Other than a possible "LOCAL NOTICE TO MARINERS" no notification to the sport diving community was made for last years survey attempt. Most boat Captains do not share their "secret spots".

 

[Raider Drake]

njdiver1, it is disturbing to read that the diving community was not specifically alerted last year. I see, at least in the present draft EA that these people should be contacted. All said and done, you have done a fantastic job, this time around as well as last, of alerting both sportfishing and diving communities of Rutgers' climate change research expedition.
So you don't know of any diving spots within or around the vicinity. What would be the procedure such that divers be alerted, if your own widespread alerts are not sufficient?
Also, I understand that you might not be privy to all Captains' "secret spots." But can you say how deep the Lillian is from the surface?

 

[njdiver1]

njdiver1, it is disturbing to read that the diving community was not specifically alerted last year. I see, at least in the present draft EA that these people should be contacted. All said and done, you have done a fantastic job, this time around as well as last, of alerting both sportfishing and diving communities of Rutgers' climate change research expedition.
So you don't know of any diving spots within or around the vicinity. What would be the procedure such that divers be alerted, if your own widespread alerts are not sufficient?
Also, I understand that you might not be privy to all Captains' "secret spots." But can you say how deep the Lillian is from the surface?

Scuba Diving - New Jersey & Long Island New York - dive Wreck Valley - Dive Sites - Lillian Shipwreck

Lillian	39 37' 00.42"	073 38' 58.43"
Lillian	39 45' 00.42"	073 39' 28.43"
Lillian	40 01' 30.40"	073 31' 38.43"

GPS numbers of New Jersey Wrecks


The Lillian Shipwreck  New York and New Jersey's (Wreck Valley)