KDWPT / Boating / Requirements / Equipment / Mufflering



Mufflering

The exhaust of every internal combustion engine used on any motorboat on Kansas waters shall be effectively muffled. The muffler system shall be in good working order and in constant operation.The sound emitted from the engine should not exceed 86 decibels on the "A" weighted scale, when measured 50 feet or more from the motorboat.

Motorboat Sound Muffling; K.S.A 32-1120

Frequently Asked Questions

  • Why have a law regulating motorboat noise?

Research conducted on motorboat noise concludes that excessive noise has an adverse impact on people and should be abated or eliminated whenever and wherever possible. Noise interference while boating enhances stressors and may not allow vessel operators to hear other boaters warning signals.

Kansas had a muffling law prior to 1994, which required above-water exhaust systems to include water induction systems that mixed with the exhaust in an effort to reduce the noise produced. This law was repealed around 1994, thereby resulting in many complaints from other boaters, fishermen, and families camping at nearby shore facilities. These complaints were from boats that had very loud exhaust systems, disrupting the environment that others were trying to enjoy.

  • Where does the existing law come from?

The National Association of State Boating Law Administrators revised a model act for Motorboat Noise on Sept. 21, 2005. This model act is intended to be used in conjunction with the Standard Automotive Engineer (SAE) standards J1970 and J2005. The model act requires all motorboats with above-water exhaust systems to install mufflers that reduce exhaust noise and limit the shoreline sound level to 75 decibels. Kansas law was drafted partly from the model act and partly from Missouri’s law on motorboat noise in an effort to obtain conformity between the states.

  • What produces the noise issue from a motorboat?

Most complaints about boat noise originate from boats that are operated without effective exhaust muffling systems. For most boats equipped with inadequate exhaust muffling, the exhaust sound level is sufficiently loud so as to be readily distinguishable from other noise sources, and the exhaust is generally routed such that it is above the water line during all modes of operation.

  • What are the primary methods for law enforcement to use in regulating motorboat noise in Kansas ?

SAE J34 is an Exterior Sound Level Measurement Procedure for Pleasure Motorboats. This is commonly known as the “pass-by noise test procedure”. This test measures the noise level as a boat passes by at 50 feet while on plane. A vessel producing 86 decibels of sound or higher, may be stopped for the second phase of testing.

The second testing phase incorporates the SAE J2005 testing procedure, which utilizes a stationary test. The vessel in question is moored or tethered. While the engine is in an idle phase, the measurement of the exhaust is taken from a distance of 3.3 feet behind the exhaust end of the vessel and 4 to 5 feet above the water level. If the decibel reading is at 91 decibels or higher, the vessel is deemed to have an inadequate muffling system.

  • What are the consequences of a vessel that measures 91 decibels or higher on Kansas waters?

During the first summer of operation (2007), officers were stressing awareness of the law and only issued warning citations to try and allow persons with motorboats in violation of decibel levels time to bring them up to the proper standards. During the 2008 boating season, officers have the discretion to issue citations and have the vessel removed from the water. Citations are class C misdemeanors that can carry a fine from $0 to $500, as set by the judge of the court where the citation is issued.

  • My vessel is equipped with a factory installed cut-out switch, commonly referred to as a Captain Call. Does this put my vessel in violation?

The current law prohibits any device which would abate the effective muffling system on a vessel. If the captain call is activated on a vessel and produces a decibel measurement of 91 or higher in the stationary test, then the device would be considered inadequate and the vessel would be in violation of the noise laws. If the device did not produce a measurement of 91 decibels, then the vessel would be found in compliance with the law. Any device other than a factory installed device that abates the effective muffling of the exhaust is deemed an illegal cut-out device.

  • Why do boat manufacturers produce boats that have ineffective muffling systems or cut-outs?

In May of 2003, the National Marine Manufacturers Association (NMMA) Board of Directors voted to formally endorse the NASBLA Model Act for Motorboat Noise, and published NMMA guidelines for boat noise. This includes engines manufactured on or after January 1, 1993 to emit no more than 88 decibels when subjected to a stationary sound level test as prescribed by SAE J2005. (Kansas is operating at 91 dB, which is less restrictive than the guidelines).

  • I have an older motorboat that I am not sure will pass the standard, what do I do?

Outboard engines route the exhaust through the prop-hub and will be far below the decibel standard. Engines that do not route the exhaust through the prop-hub and have above-water exhaust ports, may be questionable and may require muffling baffles or tips to quiet the exhaust. Tests performed on large twin-engine motor cruisers conclusively prove that high powered boats can be fitted with exhaust muffling systems producing pass by levels in the decibel range of 74 to 88 dBA measured at a distance of 50 ft. Power ratings for these boats ranged from 700 to 1600 horsepower.

  • Is there a way I can have my vessel inspected if I am in doubt about the noise of my exhaust?

Yes, you may contact your local conservation officer to set up an inspection of the vessel. This will require the vessel to be transported to a body of water where it can be properly tested.

  • How do the standards set by law in Kansas relate to those of other states?

In a study conducted in 2000 on “Motorboat Model Noise Act”, the following noise regulations were noted.

Pass by sound level in dBA @ 50 feet per SAE J34:

82 decibels – 4 states

84 decibels – 2 states

86 decibels – 11 states (Kansas level)

90 decibels – 1 state

Stationary sound level in dBA @ 1 meter per SAE J2005:

82 decibels – 1 state

84 decibels – 1 state

88 decibels – 7 states

90 decibels – 9 states (Kansas utilizes 91 decibels)

92 decibels – 1 state

Shoreline sound level in dBA during operation per SAE J1970:

75 decibels – 12 states (Kansas does not utilize this measurement)