Hey Boat Cop...

[Jetaholic]

I have a question in regards to California's noise law on boats. The one that applies to me is that motors manufactured prior to '93 cannot be any louder than 90dBA (90 decibels A weighted).
However, it does not specify from how many feet away is the sound measured, or if they measure it at idle or WOT.
Can you elaborate on this and explain how they work this law?

[SmokinLowriderSS]

Not being boatcop, all the noise regs I have sees (Cali I am unsure of) have spec'd at idle. The distance is uncertain, most I have seen 50', I think some someplace tho was 10'.
I doubt many would pass that test at WOT, even mine in her orriginal build.

[Boatcop]

California uses 2 methods to measure boat exhaust noise.
1) 1 meter behind the boat, 1 meter above the water surface, boat at idle.
90db for engines manufactured prior to Jan 1 1993
88db for engines manufactured Jan 1 1993 and later
2) Measured from the shore (any distance) at any speed. Can't be above 75db.

[YeLLowBoaT]

California uses 2 methods to measure boat exhaust noise.
1) 1 meter behind the boat, 1 meter above the water surface, boat at idle.
90db for engines manufactured prior to Jan 1 1993
88db for engines manufactured Jan 1 1993 and later
2) Measured from the shore (any distance) at any speed. Can't be above 75db.
2 Q
1 I am asumming that if your rebuild/upgrade the motor you would have to meet curent standards correct?
2 If I'm luanching my boat, they can stand on the ramp and take reading there and if I'm over 75 db I can get a ticket?

[BadKachina]

So for instance, if you were in your boat (police boat) directly behind my boat (one meter away), wouldn't your boat reflect the sound off mine and alter the test? I thought there was a provision in the test that said you had to keep in mind what the sound of the boat being tested was reflecting off of.
If so then how could you get an accurate test with your boat interfering with the test?

[Wet Dream]

Nobody said they were in their boat. They can stand on the dock and measure. And, I'm just willing to bet that there isn't a boat out there that is going to amplify the sound of any motor from bouncing the sound waves.

[Boatcop]

2 Q
1 I am asumming that if your rebuild/upgrade the motor you would have to meet curent standards correct?
2 If I'm luanching my boat, they can stand on the ramp and take reading there and if I'm over 75 db I can get a ticket?
1. Rebuilding an older engine brings it to current standards.
2. The idea behind the shoreline test, and both methods of testing, is that most people disturbed by noise are on the beach, or in marinas. Testing at idle shows that the boat is relatively quiet in these settings. e.g. when docking, beaching or cruising through a marina/no wake area. The idle test satisfies these areas.
Testing from the shoreline is meant to show the degree of noise produced by a boat already on the Lake or River, just cruising through.
While I suppose an overzealous cop might stand on the side of the ramp and test for 75db, that's not the purpose, nor the intention.
Now someone parked on the ramp just gunning the engine for the hell of it would be subject to that and also disturbing the peace charges. (Creating unreasonable noise)
The benefit of the way California does their testing is that someone already out on the lake can be as loud as they want, even cruising right by a police boat with a sound meter. They could be 120db out on the lake, as long as the reading doesn't exceed 75db when measured from the shore.
Now keep in mind that other jurisdictions measure noise in different ways, and have different standards. For example, the National Parks (Mead/Mohave/Powell) measure 82 db at 82 feet. Arizona measures 86db at 50 feet. Nevada has the same method as California, except they also include the 86db at 50 feet, so cruising by the cop at 120 db in the middle of the lake in NV doesn't cut it.
Every jurisdiction requires that ALL boats have some sort of muffling device installed.

[Wet Dream]

1. Rebuilding an older engine brings it to current standards.
That has to be a debatable grey area. What does the law specify as rebuilt? New gaskets, or plugs, or rings, or bearings, or heads. What about the old block still being used? What level is the officer/ courts going to go to, to determine how "new" my engine is? Sounds like BS to me.

[Boatcop]

I'm not a sound engineer, but through training and research, I know that reflected sound does not increase a level appreciably. The reflected noise would have to be louder than the original source to effect the reading of said source.
And as sound decreases over distance, reflected noise would always be lower than the source. Even other sound sources have a minimal effect. For example if 2 sound sources are equal (as in dual engines), the combined reading would only be 3 db higher than one source.
There is a formula to determine overall noise when there is a significant difference in noise levels. It's kind of complicated, but the main point is that before conducting any test on a boat, there should be a preliminary test of the ambient noise before testing the source.
A few years ago (2004) boaters thought the sky was falling and noise Nazis would be out in force due to the change in California's Law. (2005) So far no one has been hassled any more than before because of the change.
In reality, noise enforcement is very low on the scale, and only done in extreme cases, or where there are no muffling devices installed in the boat.
If people are reasonable about it, make an attempt to quiet the exhaust and don't purposely try to blow people's ear drums out, there shouldn't be any issues.

[Boatcop]

That has to be a debatable grey area. What does the law specify as rebuilt? New gaskets, or plugs, or rings, or bearings, or heads. What about the old block still being used? What level is the officer/ courts going to go to, to determine how "new" my engine is? Sounds like BS to me.
There is no way that an officer in the field can determine the age of an engine. That provision is primarily for manufacturers and dealers. It's inferred that if the boat is 1993 or newer, it probably has to meet the stricter standards. And if it's 1992 or older, may or may not be an older engine. But even me (a marine engine mechanic for over 30 years) couldn't tell in the field.
C'mon. We're only talking 2 db here. You guys are sweating a non-issue. No one, ever, has got a ticket or kicked off the water for being 1 or 2 db over the limit. We don't even bother with it until levels get in the mid to high 90s or above (@ 50 feet).
Any cop who is that nit-picky about 1 or 2 decibels needs to find something better to do with his time.

[mrs.rvrluvr]

hey BC you sure seem to be a reasonable cop. I just want to say thank you. I have dealt with a lot of cops that think the badge makes them god.

[Wet Dream]

There is no way that an officer in the field can determine the age of an engine. That provision is primarily for manufacturers and dealers. It's inferred that if the boat is 1993 or newer, it probably has to meet the stricter standards. And if it's 1992 or older, may or may not be an older engine. But even me (a marine engine mechanic for over 30 years) couldn't tell in the field.
C'mon. We're only talking 2 db here. You guys are sweating a non-issue. No one, ever, has got a ticket or kicked off the water for being 1 or 2 db over the limit. We don't even bother with it until levels get in the mid to high 90s or above (@ 50 feet).
Any cop who is that nit-picky about 1 or 2 decibels needs to find something better to do with his time.
I know what you're saying and appreciate the feedback, on all the issues that come up in here. It just seems odd to have a reman stipulation in there, especially when it is such a greay area. I'n not busting your nads, just questioning. ;)

[shockwaveharry]

I'll be back on the water this summer after a 2 year absence. My boat is a 2001 with a non-original 540ci motor that is loud at WOT. At idle or off plane, exhaust exits below the waterline and is exceptionally quiet. Do I need to worry about mufflers?
I'm thinking that clamp=on muffs wouldn't stay on that long being below the waterline anyway.

[Boatcop]

I'll be back on the water this summer after a 2 year absence. My boat is a 2001 with a non-original 540ci motor that is loud at WOT. At idle or off plane, exhaust exits below the waterline and is exceptionally quiet. Do I need to worry about mufflers?
I'm thinking that clamp=on muffs wouldn't stay on that long being below the waterline anyway.
Mufflers aren't something we routinely check, like PFDs or Fire Extinguishers. Usually the only time we'd worry about mufflers is when the boat's caught our attention from be excessively loud in the first place.
It's hard to say whether one boat or another is too loud, without actually hearing it and then confirming with meters.

[Jbb]

It's hard to say whether one boat or another is too loud, without actually hearing it and then confirming with meters.
Unless you work for that Marina everyone complains about...... :D

[shockwaveharry]

...Usually the only time we'd worry about mufflers is when the boat's caught our attention from be excessively loud in the first place...
So, concieveably, I could be running up River at WOT and, if an officer thinks it's too loud, pull me over and cite me for not having mufflers, even though I would pass an actual noise test?
I have never been stopped for excessive noise in the past but I'm wondering if I might be now that the laws have changed. I'll put mufflers if I have to.

[Jetaholic]

I'm not a sound engineer, but through training and research, I know that reflected sound does not increase a level appreciably. The reflected noise would have to be louder than the original source to effect the reading of said source.
And as sound decreases over distance, reflected noise would always be lower than the source. Even other sound sources have a minimal effect. For example if 2 sound sources are equal (as in dual engines), the combined reading would only be 3 db higher than one source.
There is a formula to determine overall noise when there is a significant difference in noise levels. It's kind of complicated, but the main point is that before conducting any test on a boat, there should be a preliminary test of the ambient noise before testing the source.
A few years ago (2004) boaters thought the sky was falling and noise Nazis would be out in force due to the change in California's Law. (2005) So far no one has been hassled any more than before because of the change.
In reality, noise enforcement is very low on the scale, and only done in extreme cases, or where there are no muffling devices installed in the boat.
If people are reasonable about it, make an attempt to quiet the exhaust and don't purposely try to blow people's ear drums out, there shouldn't be any issues.
And, I'm just willing to bet that there isn't a boat out there that is going to amplify the sound of any motor from bouncing the sound waves.
From a sound engineer's standpoint...
When a source wave reflects off of an object, it bounces back and travels back toward the source, creating standing waves. Depending on the distance from the source to the object that the wave reflected off of, the reflected wave will either compliment or cancel the source wave. The distance between the source and the reflective surface determines whether or not the reflected wave will be in or out of phase with the source wave. If it is out of phase, the reflected wave will attempt to cancel out the sound from the source. However, if in phase, it will compliment the source wave, which will cause a 3dB increase in the volume of the overall sound.
Of course, for a full complimentation or cancellation, the reflected wave must be an exact copy of the source wave it is reflecting back towards, and both the source wave and the reflected wave must be equal in amplitude (strength).
However, sound sources in an open outdoor environment tend to be quieter than if the same sound source were in an enclosed area. This is because sound is the movement of air. When sound is in an enclosed area, it will pressurize the air in the enclosed space more than it would the air in an open environment. It is this "sound pressure level" (aka SPL) that the cops measure when they do a noise test.
The other advantage is that the law states that it is an "A" weighted measurement. If you were to measure the same sound source with a "C" weighted measurement, it would appear to be louder because "C" weighting is a much more 'flat' method of measuring, involving more frequencies than "A" weighting, which only covers from I believe 100Hz and up and ignores everything 100Hz and below. Whereas "C" weighting covers all frequencies in the human hearing range (theoretically 20Hz-20kHz), but tapers off at the very extreme areas of the spectrum.

[yopengo]

Holy crap now I’m really confused. Too many beers. :)

[Wet Dream]

From a sound engineer's standpoint...
When a source wave reflects off of an object, it bounces back and travels back toward the source, creating standing waves. Depending on the distance from the source to the object that the wave reflected off of, the reflected wave will either compliment or cancel the source wave. The distance between the source and the reflective surface determines whether or not the reflected wave will be in or out of phase with the source wave. If it is out of phase, the reflected wave will attempt to cancel out the sound from the source. However, if in phase, it will compliment the source wave, which will cause a 3dB increase in the volume of the overall sound.
Of course, for a full complimentation or cancellation, the reflected wave must be an exact copy of the source wave it is reflecting back towards, and both the source wave and the reflected wave must be equal in amplitude (strength).
However, sound sources in an open outdoor environment tend to be quieter than if the same sound source were in an enclosed area. This is because sound is the movement of air. When sound is in an enclosed area, it will pressurize the air in the enclosed space more than it would the air in an open environment. It is this "sound pressure level" (aka SPL) that the cops measure when they do a noise test.
The other advantage is that the law states that it is an "A" weighted measurement. If you were to measure the same sound source with a "C" weighted measurement, it would appear to be louder because "C" weighting is a much more 'flat' method of measuring, involving more frequencies than "A" weighting, which only covers from I believe 100Hz and up and ignores everything 100Hz and below. Whereas "C" weighting covers all frequencies in the human hearing range (theoretically 20Hz-20kHz), but tapers off at the very extreme areas of the spectrum.
Ok, so what are the chances of a boat actually increasing the db level in an outdoor situation?

[Boatcop]

Ok, so what are the chances of a boat actually increasing the db level in an outdoor situation?
Chances are nil.
It would have to be a pure sound reflection. Direct 90 degree angle of sound waves off the reflecting surface, then another direct 90 degree reflection off of the source surface to the measuring device. (Sound meters are directional, meaning you have to point the receiving end at the sound source)
In order to significantly increase the level of the source, the reflected sound would have to be equal to or greater than the source. Since it cannot be greater, the best you could hope for would be equal (3db increase). However, sound waves in open areas will dissapate outward from the source, and from the reflection.
The omni-directional actions of sound in the outdoor environment and the angles of the reflecting surfaces will preclude getting the "pure" sound reflection required to increase the level of the source sound.

[Jetaholic]

So basically to conclude, the only time cops will really give you much of a hassle about it are:
1) If you happened to get pulled over for something else (being stupid on the water) and the cops happen to notice that you don't have any sound muffling devices installed
2) If nearby residents, people on the beach, etc etc...complain about it
3) If you're being stupid on the ramp and just revving the shit out of your engine for show off purposes, creating a nusance in doing so
4) If you're launching at the marina and a nearby LE happens to think that your boat is way too loud at idle in the marina
Is this about right?

[shockwaveharry]

So, concieveably, I could be running up River at WOT and, if an officer thinks it's too loud, pull me over and cite me for not having mufflers, even though I would pass an actual noise test?
I have never been stopped for excessive noise in the past but I'm wondering if I might be now that the laws have changed. I'll put mufflers if I have to.
Is it conceited to quote yourself? :)
I don't expect to get stopped for "doing something stupid" on the water, and I know I will pass an idle test, I guess what I'm asking is if I'm required to have mufflers no matter what.

[shockwaveharry]

Jest read in the "ride along" article in this months mag that you can be cited if you don't have muffs... Period. That's what I needed to know. :)