Multi-engine Noise Testing

[Boatcop]

I just got ahold of information on noise, noise levels, and noise testing.
Some have asked about the levels in multi-engine situations, and also about background and reflected noise.
Here's what I found out:
If 2 noise producers, close by (as in twin engines) are producing the same noise (ie 83 db), the meter, if operated properly will read 3 db higher, or 86db. (83+83=86) This 3db increase will always be 3db, no matter what level the engines are producing, as long as they are producing the same amount of noise. For example, if a twin engined boat is producing 95db from each engine, the reading will be 98db. (95+95=98)
Triple engine situations would be the same 3db increase, all other factors being equal. (95+95+95=98)
The enforcement will be based on the reading of both (or all) engines, since the statute(s) state that the noise produced by a BOAT must not be above a certain level.
In regards to background, or ambient, and reflected noise, the difference in noise levels between the ambient noise and the target is the factor.
If there is 0-1 db difference between the target and background, it would add 3 db to the target noise.
2-3 db, would add 2
4-7 db would add 1
8 or over would add 0
In a worse case scenario, reflected noise would add a maximum of 3 db to the target reading. This is assuming that the target noise is greater than the background or reflected noise.
Reflected noise can never be higher than the source noise, but CAN add (3db max) to the source noise, depending on the level of the reflected noise.
The above figures would also apply if twin engine boats are producing different levels of noise.
Example(s): Engine 1 86db and engine 2 81db=87db
Engine 1 86db and engine 2 85db=89db
Engine 1 88db and engine 2 80db=88db
Again, in this case when the 2 noise sources (engines) are from the same boat, the total reading would be correct and would be the enforcement level.
What it boils down to is that any external noise source, equal or lower than the target source will add no more than 3 db to the target source's noise level.
Hope that answers some questions, and doesn't throw too much more confusion into the mix.

[OGShocker]

Thank you Alan!

[Quality Time]

Thanks Boatcop.
Most of the discussions on here have been centered around single engine applications. Your post answers questions I have had regarding twins engine applications.
Regards

[BADBLOWN572]

Alan, what is the rule for the boats while running? I know that a lot of boat manufacturers are placing the exhaust well below water line and below the swim step which will dampen the exhaust noise tremendously. However, when running on plane, the boat exhaust will be out of the water and un-muffled. What is the ruling on that? The officer can DB the boat on the water at idle and will freequently pass, but on the top end, a completely different story. How is that going to be measured? Is the officer going to make the driver do a speed pass right in front of them?
Thanks for the update BTW.

[LHC30Victory]

Thanks Alan, I'm heading out Fri night to install a pair (oops - two pair) of Rex's tubes to my boat. I intend to get before and after readings and will post them. The 3db is good to hear, but it seems that I will be better off if one motor is quieter than the other.

[Essex502]

Thanks Alan. I know that's a big help to others on the boards with twins!
Congrats on making PowerBoat (I assume that was you in the article!).

[dirty old man]

is your test done 1 meter behind and 1 meter above the exhaust outlets?
if this is true, then it is assumed that these tests are done at idle

[Jordy]

if this is true, then it is assumed that these tests are done at idle
Yeah, and they usually have a black guy and a white girl doing the testing. Too bad that bothers you so much. :rolleyes:

[Boatcop]

is your test done 1 meter behind and 1 meter above the exhaust outlets?
if this is true, then it is assumed that these tests are done at idle
Test location is irrelevant to my post above.
That information is sound/noise science and applies to any noise level from any location and/or distance.
Regarding Danny's question about whether a boat will pass at idle and not on throttle, Arizona Law is silent on boat speed, RPM or attitude (other than the owner's :D ) All it states is 86dba from 50 feet or more, essentially the SAE J34 test.
California's law (into effect on 1 JAN 2005) addresses the idle measurement (SAE J2005), 88dba @ 1 meter back & 1 meter up, and shoreline test (SAE 1970) 75 dba any distance from shore at any speed.
I personally look at sound testing on recreational boats like a traffic cop does radar. If the the Highway Patrol doesn't get a reading on you, they don't make you speed by again so they can. For me, sound measurement is the same principle. If I don't get the reading, I'm not going to make you violate the law a second time, just to get evidence against you.
But that's just me, other's may have different procedures.
I may stop you, since I suspect you're over the limit (You all know when you're boat's too loud. Well, me too!) and check for proper muffling devices, and warn about the possible excessive noise, but I won't cite for the noise violation. If I DO get a reading, and it's high enough over the threshold, that's a different story.
I'm not talking a borderline 1 or 2 dbs, I'm looking at the mid 90s and up.
And, yes. That is me in PowerBoat, although I've yet to see the copy.

[burtandnancy]

This is all very interesting. Too bad we can't find a way to get consistant testing...

[BoatPI]

May i recomend a local marina that will provide testing free of charge.

[Quality Time]

I believe he said "consistent" testing :D

[Squirtin Thunder]

:eat:

[Kilrtoy]

I may stop you, since I suspect you're over the limit (You all know when you're boat's too loud. Well, me too!)
Hey that is not fair ALAN, I'm an expert, I'm on Hot Boat and own one, Of course I know what is loud and what is not, but you on the other hand, regardless of all the schooling you have taken , test you have passed and the fact that it is your daily job, how can you tell it is to loud, just because a device backs up your opinion. :)

[Rexone]

This is all very interesting. Too bad we can't find a way to get consistant testing...
The testing procedures (J2005 & J1970 & J34 for that matter) are quite specific and exact as to how they are suppose to be done.
The problems (where problems may exist) lie with the testing personnel, not the test specifics.
It remains to be seen how accurately the J2005 and J1970 will be administered (both take effect Jan 1 in CA).

[burtandnancy]

Rexone, what I meant by consistant was from lake to lake or river to ocean or even delta. Will the mufflers that pass in AZ or NV also pass in CA. Will coast guard, national park service, sheriffs departments, etc all do the same tests with the same equipment.

[PHOTOGLOU]

Alan what if I have a note from my mom saying loud pipes save lives any leeway??????

[Boatcop]

Rexone, what I meant by consistant was from lake to lake or river to ocean or even delta. Will the mufflers that pass in AZ or NV also pass in CA. Will coast guard, national park service, sheriffs departments, etc all do the same tests with the same equipment.
FYI, there are no Federal laws regarding noise from boats, so the Coast Guard will not be doing any enforcement on this issue.
The National Park Service has regulations unique to each park. For Mead and Mohave their regs say 82 db @ 82 feet. Leave it to the Federal Government to pull an off the wall standard out of their @ss. :hammer2:
The Glen Canyon (Powell) website doesn't specify any particular park regulation, so I'm not sure if they will be enforcing the applicable (Utah or Arizona) noise level.

[burtandnancy]

Thanks, Alan. Thats our problem, different standards for every venue, and I use every one of them although I forgot Utah as I haven't been to Powell in a couple of years. 82 dB's (at 82 feet?) is going to be real tough some of us...

[Essex502]

From the informal testing I've done...if you pass the new California test you should be okay with the states laws...remember the California jurisdiction extends to, I think, 3 miles offshore and the marinas.

[Squirtin Thunder]

FYI, there are no Federal laws regarding noise from boats, so the Coast Guard will not be doing any enforcement on this issue.
The National Park Service has regulations unique to each park. For Mead and Mohave their regs say 82 db @ 82 feet. Leave it to the Federal Government to pull an off the wall standard out of their @ss. :hammer2:
The Glen Canyon (Powell) website doesn't specify any particular park regulation, so I'm not sure if they will be enforcing the applicable (Utah or Arizona) noise level.
This is a real problem and they need to address it. I think we should have one day that everyone just says WTF and runs no mufflers or water to protest. But it would have to be on a very busy weekend to limit the tickets.
Jim

[LHC30Victory]

Here is what we got on Saturday, tied to the Marina Courtesy Dock, stern facing the lake using the Radio Shack $50 meter. The levels up to 1500rpm were about 1 to 1.5db higher than the LHC Marina meter (when he was running it right :D )
Muffler Test Results - 30 Victory W/Twin 496 HO's.
Unmuffled
Date: 11/20/2004 Temp: 65 F Humidity: high clouds/ light wind ambient noise 68 to 72db.
Port Motor Starboard Motor Both Motors
RPM 50 ft 39 in 10 ft 50 Ft 39 in 10 ft 50 ft 39 in 10 ft
idle 77 94 84 76 93 85 79 95 87
1000 81 96 N/A 81 97 N/A 85 101 N/A
1200 85 101 N/A 85 100 N/A 87 103 N/A
1400 87 103 N/A 87 104 N/A 89 105 N/A
1600 87 104 N/A 86 104 N/A 91 107 N/A
1800 87 102 N/A 88 106 N/A 92 108 N/A
2000 87 105 N/A 88 107 N/A 93 110 N/A
Levels with Rex Silencers will be measured next weekend if the weather cooperates :argue:
Sorry about the formatting, this doesn't import from Excel very well

[Essex502]

Here is what we got on Saturday, tied to the Marina Courtesy Dock, stern facing the lake using the Radio Shack $50 meter. The levels up to 1500rpm were about 1 to 1.5db higher than the LHC Marina meter (when he was running it right :D )
Muffler Test Results - 30 Victory W/Twin 496 HO's.
Unmuffled
Date: 11/20/2004 Temp: 65 F Humidity: high clouds/ light wind ambient noise 68 to 72db.
Port Motor Starboard Motor Both Motors
RPM 50 ft 39 in 10 ft 50 Ft 39 in 10 ft 50 ft 39 in 10 ft
idle 77 94 84 76 93 85 79 95 87
1000 81 96 N/A 81 97 N/A 85 101 N/A
1200 85 101 N/A 85 100 N/A 87 103 N/A
1400 87 103 N/A 87 104 N/A 89 105 N/A
1600 87 104 N/A 86 104 N/A 91 107 N/A
1800 87 102 N/A 88 106 N/A 92 108 N/A
2000 87 105 N/A 88 107 N/A 93 110 N/A
Levels with Rex Silencers will be measured next weekend if the weather cooperates :argue:
Sorry about the formatting, this doesn't import from Excel very well
Am I reading this right...that both motors running at 10' you were only 87 dB(A)? All of the 496 HO's that I've measured have been significantly louder than that. What is the design of your transom? Euro with molded swim step or no molded swim step?
Also, the 39" test...did you do it at 4' above the water per the California standard?
Just curious as we are compiling all of the results we can get on the noise issues.
Thanks for being so detailed.

[LHC30Victory]

yes you are reading it right - the formatting problem makes it difficult to follow though.
Both running at 10 ft = 87db and for the 1 meter (39") test it was done as close as I could get to 1meter. I had a pre-measured drop line to help with that. we were off set to the port side about 2 ft due to the dock - didnt want to try standing in the water :D
Here is a pic of the transom Saturday night after the Rex install:
http://www.***boat.com/image_center/data/505/778RexMuffsFullImage-med.JPG
http://www.***boat.com/image_center/data/505/778RexMuffsSideImage-med.JPG

[Essex502]

Great...thanks for the clarification. Both motors running without mufflers/silencers at 87 dB(A) is still pretty low for 10' with that swim step. I am amazed it was so low. I am assuming the tips are above water...they look like they would be.
Sweet looking setup with those Rex mufflers.

[LHC30Victory]

Thanks, we cant wait to hear the difference.
There is a LOT of water coming out of this setup, so perhaps that makes a difference. Dan from the marina was pretty amazed too, but he did his own test and confirmed it. I am on their "good boy" list I think. Doesn't matter, we launch at the Nautical anyway.

[LHC30Victory]

Another thought = Rex said that the HO's were putting out right at 94db in their single engine (CA standard) tests and that is what mine were running at, so it appears close to being what we would expect.
I would really hate to give out bad info.

[Magic34]

The Glen Canyon (Powell) website doesn't specify any particular park regulation, so I'm not sure if they will be enforcing the applicable (Utah or Arizona) noise level.
I know some people that have been cited at Powell, even before the recent talks on the boards regarding sound.

[phebus]

LHC30Victory, those look very nice installed. How did the installation go? Was it straight forward, or did you encounter any problems?

[LHC30Victory]

Other than wrestling with the 20 hose clamps, the four hard rubber exhaust sleeves, POUNDING out the Eddie Marine tips that were siliconed in :hammerhea (and busting a few knuckles doing it), and having my blood pressure shoot sky high when I took a drill to my transom, it was a piece of cake. :cool:
Really though, it was not a problem.
I would recommed to Rex or someone with a CNC machine to make some better washers for the inside than the 1/4 inch dealios that came with it. Perhaps some crescent shaped deals with a raised center to distribute the load - kinda like the Chevy valve cover things.

[LHC30Victory]

Given the variance with this meter, it looks like Boatcop's info on multiple sound sources is real close.

[Boatcop]

I've been thinking about the new test method coming next year in Ca. If you really get down to it, this may be a blessing in disguise to Hot Boaters.
Think about. There are only 2 recognized tests:
The dockside or static test, (J2005) 1 meter back-1 meter up. 90/88 dba max @ idle.
And the shoreline test, (J1970) 75 dba @ any speed from any distance.
These laws are designed to keep waterfront areas relatively free from excessive noise. Which is where most of the complaints have come from.
If you notice, there is no provision for an "on water" test, at anything above idle speed. What this means is that under the new CA law, you could buzz by a CA patrol boat out on the Lake at WOT, 110 dba, and there's nothing they could do about it. When you come right down to it, this is probably better than the 86 db @ 50 foot law, that can be enforced anywhere on the water.
I doubt that any agency is going to use up precious manpower sitting on the shore by Blankenship Bend or Pilot Rock with a noise meter, when there's more important matters to attend to. It would be an especially large waste of time and resources if you measure from the shore where there are no people.
What it boils down to is respect for the shoreside residents. Idle the boat away from shore and Marinas, particularly when there are people or homes there, and tear it up out on the Lake.

[Just Tool'n]

Here is an interesting spin that I have thought about after reading this post.
We all know the calif law is stricter than the AZ law.
We all know that tinted windows on driver side & passenger windows on calif cars are illegal. But in AZ they are legal.
So I have heard that CHP can not ticket an AZ reg car driving in calif for tinted windows.
So would a AZ registered boat meeting AZ spec, running at the calif delta be exempt, due to Az registation?
I know this is eventually going to come up.

[BoatPI]

Say shooting someone that takes a swing at you is NOT illegal in AZ. So you are in Newport Beach CA on a trip from HAVASU. You shoot a fool that took a swing at you. the cops arrive, and you say, HOLD ON HERE, I have an AZ drivers license, you cannot touch me. So......what fits?? :idea:

[Boatcop]

Keith's right.
The laws say something to the effect of "No person shall operate a watercraft on the waters of this state......."
No mention of where the boat may be registered.
The only laws that come into play regarding where the boat (or owner) is from is registration laws. If Kentucky doesn't require registration on boats less than 10 hp.. (Hypothetical situation)..and California does, California cannot require the boat from Kentucky to be registered. Although most states also say that if a foreign boat (from another state) is used for a certain length of time (usually 90 continuous days) than it IS required to meet local registration regulations.

[Dave C]

BINGO..... you hit the nail right on the head. It all boils down to respect for others.....
Boatcop makes a VERY VERY good point that we should all take under advisement.
thank you.
These laws are designed to keep waterfront areas relatively free from excessive noise. Which is where most of the complaints have come from.
What it boils down to is respect for the shoreside residents. Idle the boat away from shore and Marinas, particularly when there are people or homes there, and tear it up out on the Lake.

[DAB]

I just got ahold of information on noise, noise levels, and noise testing.
In regards to background, or ambient, and reflected noise, the difference in noise levels between the ambient noise and the target is the factor.
If there is 0-1 db difference between the target and background, it would add 3 db to the target noise.
2-3 db, would add 2
4-7 db would add 1
8 or over would add 0
Boatcop, I thought that background sound level need to be at least 10 db lower that the measured sound level. Maybe I'm not understanding... I'll type it out and hope for some answers...
4.3.4 The applicable reading shall be the average sound level measured during a period when the background sound level is at least 10 db lower than the measured sound level. Background sound level includes wind effects, noise from boats other than the one being measured, wave action, boat wakes, and other extraneous noises. Peak readings of intermittent sound levels created by wave slaps or changes in sound level due to wave action and/or engine spped variation shall not be include in the applicable reading.
Does this mean on a 40 MPH windy day if there's only a 2db delta between background and my boat they cannot use the readings?
Thanks-

[Boatcop]

I believe the standard of a 10 dba lower level for background noise was put there to be below the level where it may have an effect on the target reading. From the readings I posted, 8 db or above background noise would have no effect. While 7 db or below difference would add 1-3 db to the target reading.
Otherwise it would be a defense that the background noise affected the target's reading, and the recorded reading for that boat would be innacurate.
The highest background (ambient) noise level I've ever recorded on the Strip was 70 db. And that was on a Holiday weekend with dozens of boats going by with moderate wind. Usually on a typical weekend, background noise is in the 60-62 db range.
If the background noise is effecting the reading on a boat suspected of being above that 90 db (idle) level, then there's more of a problem than just that particular boat.

[DAB]

I believe the standard of a 10 dba lower level for background noise was put there to be below the level where it may have an effect on the target reading. From the readings I posted, 8 db or above background noise would have no effect. While 7 db or below difference would add 1-3 db to the target reading.
Otherwise it would be a defense that the background noise affected the target's reading, and the recorded reading for that boat would be innacurate.
The highest background (ambient) noise level I've ever recorded on the Strip was 70 db. And that was on a Holiday weekend with dozens of boats going by with moderate wind. Usually on a typical weekend, background noise is in the 60-62 db range.
If the background noise is effecting the reading on a boat suspected of being above that 90 db (idle) level, then there's more of a problem than just that particular boat.
Thanks for the info, I frequent Lake Mohave and wind is always gusting to the point where that is all I hear. Even though your tests showed no difference from 8 db and above does the delta have to be at least 10 db to conform to the law?

[Essex502]

Alan (Boatcop) - I took the J1970 Shoreline measurement to be at any throttle position - not only at idle. At idle would be redundant since the J2005 is the idle test.
I can't find my copy of the SAE J1970 test procedure and I'm not gonna' spend another $50 bucks to buy it from the SAE so I can't confirm this....
Mike (Rexone) - What does the J1970 procedure say? I know you have a copy of this standard.

[Rexone]

Alan (Boatcop) - I took the J1970 Shoreline measurement to be at any throttle position - not only at idle. At idle would be redundant since the J2005 is the idle test.
I can't find my copy of the SAE J1970 test procedure and I'm not gonna' spend another $50 bucks to buy it from the SAE so I can't confirm this....
Mike (Rexone) - What does the J1970 procedure say? I know you have a copy of this standard.
Let me hunt it down for you. I'm not sure if we've keyed J1970 in yet or not. I do know we finished J2005. I do remember off the cuff that it is at any speed and distance LE chooses to test at and that even though its nickname is the "shoreline test" the test can be administered from a floating platform (boat) so I think it would be a mistake to assume you can't get tested legally by J1970 in the middle of the lake. Let me find it and figure out if we have it electronic yet. As I've posted before I'll be happy to email either of these standards to anyone who wants a copy.

[BoatPI]

DaveC amen. this site is amazing for it's insight, smart experts, and ability to get to the real truth and application of almost anything.

[Essex502]

Let me hunt it down for you. I'm not sure if we've keyed J1970 in yet or not. I do know we finished J2005. I do remember off the cuff that it is at any speed and distance LE chooses to test at and that even though its nickname is the "shoreline test" the test can be administered from a floating platform (boat) so I think it would be a mistake to assume you can't get tested legally by J1970 in the middle of the lake. Let me find it and figure out if we have it electronic yet. As I've posted before I'll be happy to email either of these standards to anyone who wants a copy.
Thanks Mike..for the record I have the PDF file for J34.
If it is at any speed that implies elevated RPM and 75 dB(A) is a hard mofo to meet even with mufflers...a recent test I made with a 496 HO, Rex silencers and the boat anchored 50' away EXCEEDED the 75 dB(A) during the J1970 test as best as I could follow it.

[Rexone]

Thanks Mike..for the record I have the PDF file for J34.
If it is at any speed that implies elevated RPM and 75 dB(A) is a hard mofo to meet even with mufflers...a recent test I made with a 496 HO, Rex silencers and the boat anchored 50' away EXCEEDED the 75 dB(A) during the J1970 test as best as I could follow it.
E502, the key here is common sense on J1970. It should be obvious if there's cops sitting somewhere pointing a meter. Idle in those areas or stay well beyond 50 feet. And if you're buzzing a cop boat at speed within 50 feet you probably deserve a ticket anyway in most cases. I can think of places on the river where this wouldn't apply but not on an open lake for the most part.
As boatcop has stated numerous times it is not LE's intent to sit around and bust people for being 1 or 2 db over the limit or laying in wait to surprise test them with J1970. There may be LE exceptions to this somewhere but I wouldn't expect to see it often. They have plenty to do without worrying whether a boat is 88 or 89 db. If your running and it's 95 db, there's a noticible difference to the ear and that's they guy LE is gonna go after. Just my opinion of course.
We are keying in J1970 now.

[Dave C]

wouldn't that technically be the job of those jack-offs at the marina?? :rollside: :rollside:
As boatcop has stated numerous times it is not LE's intent to sit around and bust people for being 1 or 2 db over the limit or laying in wait to surprise test them with J1970.

[Rexone]

Thanks Mike..for the record I have the PDF file for J34.
If it is at any speed that implies elevated RPM and 75 dB(A) is a hard mofo to meet even with mufflers...a recent test I made with a 496 HO, Rex silencers and the boat anchored 50' away EXCEEDED the 75 dB(A) during the J1970 test as best as I could follow it.
As a follow up 75 is not very noisy. I've checked boats where hull noise approaches that. Again the key is common sense by the boater.
Also 50 feet is not a requirement of J1970. So if you go by the tester at 20 feet or half a mile he can test you and bust you under J1970 if you exceed 75 db. So my advice is don't go anywhere near the 50 foot mark. J1970 was written with vague language and no distance requirement (IMO) so LE has latititude to enforce when necessary with out a measured course (like J34 requires).

[Rexone]

Let me hunt it down for you. I'm not sure if we've keyed J1970 in yet or not. I do know we finished J2005. I do remember off the cuff that it is at any speed and distance LE chooses to test at and that even though its nickname is the "shoreline test" the test can be administered from a floating platform (boat) so I think it would be a mistake to assume you can't get tested legally by J1970 in the middle of the lake. Let me find it and figure out if we have it electronic yet. As I've posted before I'll be happy to email either of these standards to anyone who wants a copy.
Essex502, I have J1970 & J2005 available electronically now. Anyone who wants them PM me your email address. I have them as word.doc files.
Also I was wrong on the floating platform deal. The test can be administered from a boat or floating dock but it must be moored or anchored within 20 feet of shore. Thats what I get for going off memory. :rolleyes:
So there you have it. If you survive the dock test and shoreline test and make it to the middle of the lake you should be ok I guess. Time will tell.

[shueman]

I say there be a "pre-season" testing location set up at or near the favorite boating locales, just like some places do for "safety equipment". You get your boat tested and "certified". They give you a little sticker for your hull/windscreen, etc. that says "I'm legal". If you don't pass, they should have recommended modifications to get certified for your particular boating place of preference.
Just my thoughts....

[LHC30Victory]

Well, we finally got out when the wind was not too bad and took some "after" readings on the HO's wiht Rex mufflers. Because of the lack of time to do the whole rpm range we did pre-install, we had to settle on the important figures.
IDLE at 39":
Port motor - before=94 after=87
Starboard motor - before=92 after=87
both - before=95 after=89
IDLE at 50'
both - before=79 after=73
Marina Rules (10 feet?)
both - before=88 after=82
The performance didn't change appreciably, maybe lost 100RPM but due to different loads and weather/sea condidtions, it is not an issue with me.
On my last post about the Marina and its peeps, I had good things to say about Dan and it seemed that the Marina was trying to play nicely. HOWEVER this Sunday they were back to being their usual selfs again. They didn't have me on their tested list so had me retest despite seeing the mufflers on and that I passed w/o mufflers per Dan.
I believe that this guy's name was Jim. He had me start the motors and then asked me if they were idled down all the way. I had to remind him that they were stone cold (he saw me just launch it :supp: ). he then took his measurement and told me I failed :idea: I turned one motor off and he said I passed :messedup:
I then got out and looked at his meter while he was writing and saw it was on A scale but FAST RESPONSE and MAX HOLD!!!!! When I told him that I thought those settings were wrong, he began to lecture me about how Marina rules didn't have to follow either AZ or CA law and that if I were to go to a restaurant that had a sign "no shoes, no shirt, no service" they could refuse service to any person. WTF? Didn't they get the message yet?

[repo man]

i wish we could find another state to take our loud boats and all the money we spend on them and in them to. havazoo and parker would dry up and blow away. it's sad to say more people are going to die as a direct result of this law when they can't hear you coming and turn in front of big fast whisper quiet boats with no breaks. 5dbs isn't worth even one life.