I put money on it that he had it on C-scale or unweighted. The C-scale will read much louder if there is a lot of low frequency sound, which V8 engines do.

I have a sound level meter which reads both A and C scales. I'll give it a try with my Trans Am with LT1 engine and see what happens. Also 68 ambient is VERY high. If you are on the lake with nothing else going on, it should be more like 35 to 45. In fact, if you start out at an ambient noise level of 50 or above, don't even bother running the test.

Michael

I usually don't post here, but I was told this was being discussed, and I have done a bunch of research on it with the current laws, (and th proposed changes they have been trying to push through).

Here is the Michigan law as posted. The shoreline, moving, law is the one that is almost impossible to beat. Even the outboard Sheriff's boat failed it when they ran the tests (in Higgins I believe, I'd have to check my records).

If you want, most know where to find me, but I'll try to check this thread once in awhile.

6.10 Equipment Requirements and Required Personal
Flotation Devices

A. Misdemeanor—Equipment Requirements

MCL 324.80156 details the sound requirements for motorboat mufflers and underwater exhaust systems. MCL 324.80156(1) states:
*MCL 324.80156(2) allows the DNR to establish rules for alternative sound level tests and maximum decibel levels.

“Subject to subsection (2),* a person shall not operate a motorboat on the waters of this state unless the motorboat is equipped and maintained with an effective muffler or underwater exhaust system that does not produce sound levels in excess of 90 dB(A) when subjected to a stationary sound level test as prescribed by SAE J2005 or a sound level in excess of 75 dB(A) when subjected to a shoreline sound level measurement procedure as described by SAE J1970. The operator of a motorboat shall present the motorboat for a sound level test as prescribed by SAE J2005 upon the request of a peace officer. If a motorboat is equipped with more than 1 motor or engine, the test shall be performed with all motors or engines operating. To determine whether a person is violating this subsection, a peace officer may measure sound levels pursuant to procedures prescribed in SAE J1970, issued 1991-92.” A person who violates MCL 324.80156(1) is guilty of a misdemeanor punishable by: • imprisonment for not more than 90 days; and • fine of not less than $100.00 or more than $500.00. MCL 324.80156(6). In addition, the person must install a muffler or underwater exhaust system that meets the act’s requirements before putting the vessel back in use. Id.


R 281.1238 Mufflers; cut outs.
The exhaust of all internal combustion engines used on any waters of this state shall be muffled effectively by equipment so constructed and used as to muffle the noise of the exhaust of the engine in a reasonable manner. The use of cut outs, bypasses, or similar devices is prohibited, except for vessels competing in a boat race or regatta sanctioned by the department under sections 151 and 152 of the act. A modern device, underwater exhaust system or a system discharging cold water through the exhaust of an inboard engine, each of which is capable of muffling the noise of the exhaust of the engine in a reasonable manner, shall be considered as meeting the requirements of this rule.

Yeah, when he said ambient was that high I thought something was up rite away. I really appreciate everyones input on this. I will definately have ammo now. I had no idea about the weighting scales.

Rat, I saw you posted on chickens thread in our regional section. This sucks because I'm a guy who is trying to be compliant and will be into this for over $1000 if I buy the meter.

J, copy and paste this, then laminate it and carry it on the boat to make sure they perform the test properly. IMO there's no reason to buy an expensive meter as it will be a moot point if Jonny Law says you're over.

Procedure 4.

4.1 Measurement Site—A suitable site is a body of water free of large obstructions or reflective surfaces such as
buildings, boats other than those involved in this procedure, large embankments or breakwaters, etc. for a
minimum distance of 8 m (25 ft) from the boat being measured. The boat being tested shall either be moored
to a dock or lashed to another boat. If moored to a dock, the dock shall be of open construction so that it
presents a minimum of reflecting surfaces. If the measurement is made in open water, the boat being
evaluated shall be lashed to the measurement boat to prevent relative motion and to allow positioning of the
microphone in the prescribed location. The measurement boat shall be positioned to minimize reflected
sound.

4.2 Boat Operation—The engine shall be operated at low idle speed within the engine manufacturer's
recommended operating range, in neutral gear if so equipped. For motorboats without a neutral gear, the
engine shall be operated at its lowest operational speed. The engine shall be operated for a sufficient amount
of time to allow water to flow through the exhaust system before taking measurements.

4.3 Measurements

4.3.1 The microphone shall be placed at a distance of 1.2 to 1.5 m (4 to 5 ft) above the water and no closer than
1 m (3.3 ft) from the vertical projection of any part of the boat in the area adjacent to the exhaust outlet(s).

4.3.2 The meter shall be set for slow response and the A-weighting network.

4.3.3 The observer reading the meter shall not be closer than arm's length from the microphone to minimize sound
reflections.

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 speed variation shall not be included in the applicable reading.

4.3.5 The observer shall record the applicable reading and the background sound levels taken immediately before
and immediately after the applicable reading.

Am I reading this right...switchable mufflers and silent choice are prohibited?

There meter is messed up. Guy on another thread put up the EXACT same reading as jrider put up. 103.9.... Cops don't ever keep their breathalyzers calibrated so wtf would there decibel meters be any different.

The way some cops read it they say they are prohibited. The reality is silent choice is fine because you are going from one form of muffling to another. You would have to pass the test with the loudest form of exhaust equipped on your boat though.

Could not be too far off it a few things where taking place.

I was tested on the 4th on the St Criox and was very SURPRISED and happy what mine came in at.

But I will say several major things helped with a more then accurate reading then I ever have!!
First, he let the boat run several minutes BEFORE setting up the measurement
Second, he used the proper 'sticks' for measing where the meter is supposed to be at and not just held out at arms reach.
Third, his boat was on the SIDE of mine! So no bounce back of sound. Many years ago I was tested and the DS had his boat right behind me and I read over 110!!
Fourth, I made damn sure that the back of the boat was pointing as far away as possible from ANYTHING! Shore, other boats as well as other boat traffic. I chose the location and made sure we floated that way :)
Lastly, he was the more sincere pleasany officer I have ever dealt with on land or water!
I have stock twin 502's, y-pipe with straight out exhause as well. No diverters on the ypipe at all.
I have am also runnint Teague 4.5's switchable tips. The switch is/was closed during this test as its wired closed with the main power switch.
He came up behind us in the no wake area and was commenting on my sound level.
I told him my version of things :) and he still wanted to test :(
After everything he agrees with me that the fact of still have the open ypipe allows too much water to go our the prop exhaust then the tips, this increasing the sound level. He too was surprised that I read out at only 82! :)
My tips are also on top of my swim platform and is in high above water level :(

When the meter first started it peaked at 112, then 107, 105,101, 99, 96 and then settled on 82 :)

So thus my final thought is that if he did everything else properly, did he leave the meter running LONG enough to let it settle down? It really seemed like he had the meater there for well over 3 minutes and the wife said over 5 minutes he held it there!

Just my thoughts and personal experience!

Wecome back Paul!!!!

Tired of talking to himself