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Essex502
03-29-2004, 07:35 AM
We did some informal testing of exhaust noise this past weekend in Havasu and here are the results:
496 HO MAG with above waterline exhaust equipped with hardin Marine Silencers - 89 dB-A (this boat was significantly louder before the mufflers we added but we didn't test it at that time).
HP525 above waterline exhaust equipped with no silencers - 100 dB-A
502 MAG with below waterline exhaust with no silencers - 84 dB-A
The first two boats had molded - Euro style - swimsteps which undoubtedly magnify the sound.
The above tests were conducted in accordance the SAE J2005 test standard in use in many states. A Radio Shack Digital meter was used and is advertised as accurate to +/- 2 dB.
We conducted the test early in the day in Steamboat Cove so background noise and echos from a dock or other structures with minimized.
Hope this helps any of you on choosing whether or not to muffler you rides. We'll be doing more testing during the season and I'll post the results of each test.

rivercrazy
03-29-2004, 08:23 AM
With respect to the 496HO tests, is that the slip on silencer or the integrated muffler/tip.
Sounds like I'd be OK idleing!

Sun burners
03-29-2004, 08:33 AM
??? 502 mag euro step with silent choice?:)

bigq
03-29-2004, 08:44 AM
and what is the legal limit?

beer hunter
03-29-2004, 08:47 AM
Damn Mike, I completely forgot to have you test the boat last weekend :confused: Who's 502 powered boat was that? :)

beer hunter
03-29-2004, 08:49 AM
Originally posted by bigq
and what is the legal limit?
J2005 stationary test. This test is from 4 to 5 feet above the water at 3.3 feet from the transom. Test is at low idle speed in neutral. For engines manufactured before January 1, 1993, a noise level of 90 dB(A). For engines manufactured on or after January 1, 1993, a noise
level of 88 dB(A)

NastyOne
03-29-2004, 08:50 AM
I forgot what the limet is on db's for Havasu:confused:
And are they checking boats at the ramps?

572Daytona
03-29-2004, 08:57 AM
What if your boat doesn't have a Neutral? My drive is always spinning.

NastyOne
03-29-2004, 08:59 AM
Originally posted by 572Daytona
What if your boat doesn't have a Neutral? My drive is always spinning.
Then your ****ed.:D

Essex502
03-29-2004, 09:03 AM
The 502 tested was our boat right at the swim step well under the 1 meter distance.
The 496HO Mag was with the integrated tip and silencer I believe. There's a good write-up on this setup at:
Silencers on 496HO Mag (http://www.lasvegas***boats.com/cgi-bin/forum/ikonboard.cgi?s=406836f63487ffff;act=ST;f=3;t=1593 )
One boat that was attempting to launch on Saturday was tossed from the Marina as being too loud. Right now I believe the Marina, at least, is subjectively rejecting loud boats.

Essex502
03-29-2004, 09:11 AM
Originally posted by beer hunter
Damn Mike, I completely forgot to have you test the boat last weekend :confused: Who's 502 powered boat was that? :)
As we used to say in Gardena....snooze you loose! next time, Mate! :D

welk2party
03-29-2004, 09:45 AM
That is only a marina deal. The people there are jerks. The noise law has not come into affect until January.

RandyH
03-29-2004, 10:34 AM
Originally posted by NastyOne
Then your ****ed.:D
No, I believe the officer holding the DB meter is ****ed at 4 feet from the transom. Sorry Officer, I told you I didnt have Nuetral.
RandyH