Muffler design

[phebus]

Just a thought, but if the new mufflers that are being produced had an angled cut that exhausted outwards toward the sides of the boat, would a meter reading from behind the boat read lower? If you were dead on behind the boat, the exhaust wouldn't be pointed at you at all, and if you were off to one side or the other, only one exhaust would be pointed at the meter.
Probably to simple to make sense, as noise is noise, but if it wasn't direct, common sense (yes, something I'm lacking) would seem to me would read lower on a meter.

[THATJEFFGUY]

Hey these MUFFLERS (http://www.jcwhitney.com/autoparts/Product/showCustom-0/Pr-p_Product.CATENTRY_ID:2009649/c-10101/Nty-1/p-2009649/Ntx-mode+matchallpartial/N-10101/tf-Browse/sct-body/s-10101/th-StoreCatalogDisplay/Ntk-AllTextSearchGroup/ss-10101?Ntt=stacks) would look pretty sweet too !

[Rexone]

Text pulled from SAE J2005 regarding the above...
"In most applications involving thru-transom exhaust the microphone location should be I m (3.3 ft) aft of the intersection of the vertical plane of the aft-most part of the transom and the vertical plane of the port-most or starboard-most part of the gunnel at the specified height of 1.2 to 1.5 m (4 to 5 ft) above the surface of the water with the microphone oriented toward the exhaust outlet(s)."
So it is not center behind the boat per spec.

[Rexone]

The following is the part that will be tough to administer per spec in my opinion in the field on a busy weekend with other boats coming and going etc etc etc.... How LE and the courts will decipher and treat all this remains to be seen.
Per J2005...
"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.
5 General Requirements
5.1 The measurements shall be conducted only by persons qualified by training to perform these measurements.
5.2 Proper use of all test instrumentation is essential to obtain valid measurements. Operating manuals or other literature furnished by the instrument manufacturer should be consulted for both recommended operation of the instrument, and precautions observed.
5.3 Proper acoustical calibration shall comprise the complete measurement system including extension cables. Field calibration shall be performed immediately before and after each test sequence.
5.4 A measurement shall be invalid if changes in the background sound level affect the applicable reading.
5.5 The use of the word "shall" in the procedure is to be understood to be mandatory. while the word "should" is to be understood as advisory."

[Squirtin Thunder]

Hey these MUFFLERS (http://www.jcwhitney.com/autoparts/Product/showCustom-0/Pr-p_Product.CATENTRY_ID:2009649/c-10101/Nty-1/p-2009649/Ntx-mode+matchallpartial/N-10101/tf-Browse/sct-body/s-10101/th-StoreCatalogDisplay/Ntk-AllTextSearchGroup/ss-10101?Ntt=stacks) would look pretty sweet too !
So you like this look ??? It is an alternative to pass the J-2005.
http://www2.***boat.com/image_center/data/500/2311unchexhaust5.jpg
BTW- Thanks for posting that, Just copied it to carry in the boat !!!

[paradigm shift]

They do work.
http://www2.***boat.com/image_center/data/500/2077Snuffler_007.jpg

[Essex502]

The following is the part that will be tough to administer per spec in my opinion in the field on a busy weekend with other boats coming and going etc etc etc.... How LE and the courts will decipher and treat all this remains to be seen.
Per J2005...
"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.
5 General Requirements
5.1 The measurements shall be conducted only by persons qualified by training to perform these measurements.
5.2 Proper use of all test instrumentation is essential to obtain valid measurements. Operating manuals or other literature furnished by the instrument manufacturer should be consulted for both recommended operation of the instrument, and precautions observed.
5.3 Proper acoustical calibration shall comprise the complete measurement system including extension cables. Field calibration shall be performed immediately before and after each test sequence.
5.4 A measurement shall be invalid if changes in the background sound level affect the applicable reading.
5.5 The use of the word "shall" in the procedure is to be understood to be mandatory. while the word "should" is to be understood as advisory."
Do you think any of these clauses will be known to LE when they conduct there testing? Probably NOT!

[phebus]

Regardless of all the legal hokus pokus, my thoughts were that in reality, L.E. or whoever is testing your boat, woud go to the transom, and at the required distance and heigth get a reading on their meter. I would think that if your exhaust was pointing to opposing sides, the meter would be "fooled" into a lower reading.

[dirty old man]

I've seen side exhaust on some non-performance boats, ie; Crownline, etc., but they aren't that loud to begin with. The big block chebby sounds sucks. You can't do that on twin powered boat tho
Where are we going to install our water cooled catalytic's when they mandate that?

[Essex502]

Regardless of all the legal hokus pokus, my thoughts were that in reality, L.E. or whoever is testing your boat, woud go to the transom, and at the required distance and heigth get a reading on their meter. I would think that if your exhaust was pointing to opposing sides, the meter would be "fooled" into a lower reading.
In Havasu Marina you might make the problem worse as they test the boat in Lane #1 - right next to the courtesy dock and a concrete wall. The reverberation might amplify the noise level.
You are right...sound to some extent is directional. That is why the mandated tests are with no "structure" nearby and away from other sound sources.

[phebus]

In Havasu Marina you might make the problem worse as they test the boat in Lane #1 - right next to the courtesy dock and a concrete wall. The reverberation might amplify the noise level.
You are right...sound to some extent is directional. That is why the mandated tests are with no "structure" nearby and away from other sound sources.
So, if you go to the Marina to be tested, buy two right sided exhaust tips since they test from the left side by the wall. :D Actually, if they were straight clamp ons, you could point them in any rirection you would want, by swivelling them prior to tightening the clamp. If the sound was just not pointed directly at the meter, and you claim that sound is to an extent somewhat directional, it would seem a tip with a directional outlet may be beneficial.

[Beer-30]

I really would like a switchable setup and both CA and AZ don't really specify against switchable. Don't want to pull the motor for the Merc downpipe, but HARDIN has some nice looking replacement tips that have all of the switching mechanics inside the compartment. They just look like a normal slant tip out the transom. Just wonder if they will legal an HO. They are certainly affordable from CP or EDDIE. Any of you folks experience these?

[Rexone]

Excerpt from CA law...
654. (a) (1) For the purposes of this section, a "muffler" or
"muffler system" is a sound suppression device or system that is
designed and installed to abate the sound of exhaust gases emitted
from an internal combustion engine and prevents excessive or unusual
noise.
(2) For the purposes of this section, an underwater
through-the-propeller-hub exhaust outlet system is a muffler system.
(b) A motorized recreational vessel that is operated in or upon
the inland waters, or in or upon ocean waters that are within one
mile of the coastline of the state shall be equipped at all times
with a muffler or a muffler system that is all of the following:
(1) In good working condition.
(2) In constant operation.
(3) Installed in a manner that effectively brings the vessel into
compliance with Section 654.05.

[Essex502]

I really would like a switchable setup and both CA and AZ don't really specify against switchable. Don't want to pull the motor for the Merc downpipe, but HARDIN has some nice looking replacement tips that have all of the switching mechanics inside the compartment. They just look like a normal slant tip out the transom. Just wonder if they will legal an HO. They are certainly affordable from CP or EDDIE. Any of you folks experience these?
Switchable exhaust muffling, like Rexone pointed out in the CA regulation - and this includes "Captain's Call", "Silent Choice" and others are not legal in CA or AZ.

[Beer-30]

Thanks for pointing that out. In the Mar ***boat mag, the breakdown didn't show that information.
Oh well, just an idea.

[superdave013]

mine come out of the turbos, transition up to 4", to a muffler on each side and then some turnups that point up and to the side a little.