In the interest of protecting public health, safety and welfare, all available research concludes that excessive noise has an adverse effect on people and that it should be abated or eliminated whenever and wherever possible. Regarding noise caused by recreational boating, research conducted by the U.S. Environmental Protection Agency (EPA) confirms studies conducted by law enforcement agencies and the boating industry that identify exhaust noise as the number one source of boat noise.

Complaints about boat noise from inboard and outboard powered boats in the decades of the ‘60’s and ‘70’s were generally the result of after-market modifications by their owners. However, the advent of the “off-shore” performance boat in the ‘80’s and ‘90’s along with proliferation of personal watercraft resulted in a rapid increase in the number of complaints about boat noise. During these two decades, the size of a typical pleasure motorboat increased substantially while the maximum power of the engines increased by a factor of approximately 10. Consequently, the pass-by sound level for production line boats increased by as much as 20 dB. This four-fold increase in sound level energy was primarily due to the presence of offshore boats that were being sold with above-water straight-through exhaust systems.

Research indicates that boats with above-water exhaust are up to four times louder than their under-water exhaust counterparts. The marine manufacturing industry has responded by incorporating means of expelling exhaust gases through the hub of the propeller in many of today’s pleasure motorboat propulsion systems. Boat noise from exhaust is greatly reduced by routing exhaust gases beneath the surface of the water. However, many of these exhaust systems on the more powerful motorboats include provisions in their design whereby the operator can activate a “cutout”, which reroutes the exhaust to above-water and defeats the boat noise reductions otherwise achieved. Boat operators will use a cutout in order to realize less restriction on the exhaust system and greater performance (speed) from the boat. Despite technological advancements in exhaust system design to better muffle boat noise from exhaust systems, substantial concerns over boat noise continue to be expressed by sail boaters, canoers, kayakers, property owners and other parties interested in enjoying the peace and quiet of waterscapes. Consequently, additional efforts to reduce exhaust noise are required.

Growing efforts to reduce boat noise are evident the volume of states in the U.S. that have enacted boat noise regulations. In September of 2000 the National Association of State Boating Law Administrators’ (NASBLA) Law Enforcement Committee completed a survey of states’ boating laws in preparation for printing their Reference Guide to State Boating Laws – Sixth Edition. The project was funded by a grant from the Aquatic Resources (Wallop/Breaux) Trust Fund administered by the U.S. Coast Guard.

Surveys were mailed to state boating law administrators from the 50 United States and territories. Responses were received from all but the District of Columbia, Hawaii, Louisiana, and West Virginia, whose answers remained the same as reported in the fifth edition. All answers were taken as fact and have been reported by NASBLA as such. All laws detailed in the reference guide were in effect as of September 200 except as otherwise noted. The laws are subject to change without notice by agencies, states or the U.S. Coast Guard.

Thirty-one (31) states in the U.S. have a maximum noise level for motor boats; twenty-five (25) do not. The standard for maximum noise levels ranges from 75 to 90 decibels (dB). The standards used by most states are SAE J-2005 and SAE J-1970. Developed by the Society for Automotive Engineers (SAE), SAE J-2005 and SAE J-1970 are sound testing procedures that measure the decibel level of stationary and moving motor boats respectively. Using the SAE J-2005 (stationary test), most states set maximum noise levels at 86 to 90 dB. When the SAE J-1970 (shoreline test) is used, the maximum noise level is commonly 75 dB. The distance of measurement for most states is fifty (50) feet. Depending on the state and the manufacture date of the motor, maximum noise levels may differ. The penalties for exceeding motor boat noise levels range from $0 to $1,000.
Altering factory mufflers is a violation of the law within thirty (30) states. Twenty (20) of the thirty (30) states that have muffler alteration laws also enforce maximum noise levels for motor boats.

A summary of these state boat noise laws, excerpted with permission from the NASBLA Reference Guide to State Boating Laws – Sixth Edition, can be found on the Quest Technologies website. Quest Technologies is a world leader in the design and manufacture of a broad range of noise monitors (a.k.a Sound Level Meters, SLM, Real-time Frequency Analyzers, RTA) suitable for the measurement boat noise by law enforcement, state boating law administrators, marine manufacturing engineers, park police, environmental noise consultants and other interested parties. Quest’s SoundPatrol DP Series is designed specifically for noise ordinance enforcement and is an ideal tool for boat noise law enforcement. Quest Technologies complete line of noise dosimeters, sound level meters (SLM) and real-time frequency analyzers (RTA) can be accessed from the of the Quest Technologies website. Quest Technologies is also capable of providing training seminars in the correct procedures for the measurement of noise.