Q&A

Airboats are uniquely loud watercraft which create a noise disturbance that exceeds any other type of vessel in common use along the coast and waterways of Maine. Testing in 2020 found that these boats generate an average of 98 decibels (dbA), and as much as 106 dbA. when measured at distance of 50 feet. This is about as loud as a Bell J-2A helicopter and a level which the CDC warns can cause hearing damage after just 15 minutes. Airboats operating in populated waterways are like aircraft driving through neighborhoods. The boats can frequently be heard for miles away, often before they are seen, and for miles inland. (See the noise radius of various airboats and other noise sources to get a sense of just how loud they are.) They operate in the early morning hours, frequently before 6 am and occasionally as early as 4 am, awaking residents and campers along the shoreline. The number of boats operating, although still small, has slowly grown in recent years, and the frequency of their operations has increased. The noise has affected hundreds of users and residents of the waterfront and generated thousands of complaints in recent years due to growing use, especially in the northern estuaries of Casco Bay.

Why are airboats so much noisier than lobster boats and other watercraft?

Airboats are driven over the water by a large fan or propeller, much like an airplane’s propeller. The propeller is powered by a gas engine - often a converted pickup truck engine. The noise from the engine is, or should be controlled by a muffler, as in other watercraft. However, when an airboat gets up to speed, the noise of the propeller overtakes the noise of the engine so what you hear is the roar of the whirring propeller. The propeller noise will vary depending on the number and pitch of the propeller blades. Some effort has been made in the past by airboat and propeller manufacturers to reduce airboat noise, but without great success. The noise of airboats is particularly objectionable to coastal residents because they operate along the shore, in shallow water or on the tidal flats, unlike other commercial boats which mostly head offshore

Aren't lawn mowers, leaf blowers, table saws, nail guns and other equipment commonly used in neighborhoods just as loud as airboats?

No. Airboats are much louder than all of these other types of equipment. This is easy to appreciate by looking at the noise radius of various airboats and other noise sources. In July 2020 the Maine Warden Service published a report of a test of 13 airboats currently in use in Maine. In one test sound levels were measured for each boat from a distance of 50 feet at various throttle settings. At full throttle, the boats tested ranged from 91 dbA to 106 dbA with an average of 98 dbA.

For comparison, an EPA study (p.13) found that walk-behind power mowers emit 65- 72 dbA when sound is measured at a distance of 50 feet. Another study found that a variety of gas-powered leaf blowers, a notoriously loud type of power lawn equipment, emit only 77-81 dbA measured at 50 feet. Perception of loudness approximately doubles for every 10 dbA increase, so airboats sound approximately 4 times louder than the average gas powered leaf blower, and 8 times louder than the average lawn mower. A similar relationship holds for other commonly used power equipment. It is also worth noting that most municipal noise ordinances prohibit operation of lawn and other power equipment during nighttime hours.

Is it possible to make a quiet airboat?

Quiet is relative. It is probably not possible to make an airboat that could meet Maine's statutory noise limits for other watercraft (75 dbA at 50 feet). However, it is possible to make airboats much quieter than most are now. For example, two of the airboats tested by the Maine Warden Service in 2020 topped out at 91 dbA (measured at 50 feet distance). The difference between 91 dbA and 98 dbA may not sound like much, but is actually a big deal. To help visualize it, check out the difference in noise radius.

AIRBOAT OPERATIONS IN MAINE

Are airboats legal in Maine?

There is no law specifically prohibiting airboat use in Maine. The current state law addressing watercraft noise would, if applied to airboats, make most of them illegal to operate. Many people affected by airboat noise have argued the law should apply to airboats, but operators argued they were exempt because the law regulates engine noise only and airboats generate most of their noise via the propulsion fan rather than the engine. In early 2020 the legislature passed a law specifically exempting airboats from the existing watercraft noise rules and directed the Department of Inland Fisheries and Wildlife (DIFW) and Department of Marine Resources (DMR) to create special noise rules for airboats. No rules have yet been established, so at this time airboats can legally operate without any restriction on noise levels or time of day.

What are airboats used for in Maine?

At this time airboats are primarily used by the Maine Warden Service, a few local police departments such as the Town of Brunswick, and shellfish harvesters. The biggest concentration of airboats in recent years appears to be in the tidal waters of Freeport, Brunswick, and Harpswell in Casco Bay.

Have airboats always been used along the coast?

No. A few airboats have been in sporadic use since the 1990s, but use has greatly expanded for shellfish harvesting since 2015. There were very few complaints about airboat noise prior to 2015.

Could airboat use be legally expanded in Maine?

Yes. There is currently no legal restriction on airboat use in Maine with regard to waterway, purpose of use, or time of operation.

AIRBOAT NOISE RULEMAKING IN MAINE

Why are airboat noise rules being discussed now?

A large number of complaints about airboat noise from coastal residents and waterfront users prompted the Maine state legislature in early 2020 to clarify that previously existing watercraft noise rules did not apply to airboats. DIFW and DMR were directed to propose new noise rules specific to airboats. in June 2021 temporary nominal interim noise limits were approved that provide minimal relief from the noise, and a stakeholder group was formed to study the issue further. In 2022 new interim noise limits for airboats were enacted which are set to expire in October 2023. For full details of this history read the background.

Who are Citizens Against Airboat Noise (CAAN)?

We are residents and users of the waterfront who have been impacted by noise from increasing airboat operations along the coast of Maine. Read about our background. Our constituency is concentrated in Freeport, Brunswick, and Harpswell primarily because these areas have been the areas most affected by airboat operations.

Does CAAN want to ban airboats in Maine?

No. Our group seeks to enact rules that minimize airboat noise, especially during early morning hours. We are seeking collaborative solutions to reduce airboat noise with the minimum possible impact on operators, and support a program to reduce the financial impact of airboat modifications required to comply with any new rules.

Why do airboats require special rules? Can't they follow the noise rules for all other watercraft?

If the current rules for other watercraft were applied to airboats then most or all airboats would be banned from operation because their noise exceeds the current limits. The point of special noise rules for airboats is to allow them to operate legally. We agree that new rules exempting airboats from the old rules are appropriate, but we want airboat noise rules to account for the rights of shorefront users and residents to live and recreate without unreasonable noise pollution, especially in the overnight hours.

Will proposed airboat noise rules affect other types of watercraft, such as lobster boats?

No. All other watercraft are subject to the existing watercraft noise rules, which are already stricter than any proposed rule for airboats. New rules specifically for airboats effectively relaxed previous noise standards to make rules that are attainable by airboats. A more logical concern is just the opposite, that looser airboat rules could set a precedent that other classes of watercraft could follow.

Will airboat noise rules restrict use by emergency services or state agencies?

We recommend that police department and state agency airboats operated on public business should be exempt from noise rules.

CHOOSING NOISE LEVEL LIMITS FOR AIRBOATS

How should we choose fair noise rules for airboats?

We support setting a current standard that is attainable with available technology, with a focus on compliance of new airboats. The standard should be determined by what is right and reasonably possible, not what 80% of current boats already meet. Imagine if vehicle safety inspection and emission standards were codified based on the the average standard of a car in 1980. The standards should also be enforceable, repeatable, and minimize inconvenience to airboat operators.

What noise rules are "attainable" for airboats?

We believe that a daytime limit of 90 dbA as measured from 50 feet is achievable for properly equipped airboats. This limit is derived from the results of noise testing performed by the warden service in 2020 and our own conversations with manufacturers of airboat parts and equipment. Note that this limit permits boats that are considerably louder than the state limit for all other watercraft, which are limited to 75 dbA as measured at 50 feet, and considerably louder than the level of noise permissible in residential zones in most municipal noise ordinances.

Please note that CAAN previously supported noise limits measure from shoreline, which is currently in law. However, experience with the current law suggests shoreline limits impose an unfair enforcement burden on the warden service and local officials, who have better things to do than chase loud airboats.

What should airboat noise limits be during overnight hours?

During overnight hours, from 7 pm to 7 am, we believe airboats should meet limits analogous to current noise rules for other watercraft (75 dbA measured at 50 feet). Alternatively, we could support the establishment of noise sensitive zones in which nighttime airboat operation is restricted, while still allowing operation in less sensitive areas. Local input should be integral in the establishment of any such areas.

Does the current daytime limit of 90 dbA measured from the shoreline offer relief from airboat noise?

No, even the loudest boat tested by the Maine Warden Service meets this limit when measured at a distance of 500 ft, a typical distance for airboats in transit.

AIRBOATS AND SHELLFISH HARVESTING

Will airboat noise rules hurt shellfish harvesters?

Most shellfish harvesters use skiffs rather than airboats, they are not affected at all.

For harvesters that use airboats:

We support phased in noise limits with a focus on compliance of new boats. We recommend a noise limit of 90 dbA at 50 ft, which experience shows is acheivable. A boat that meets this standard could be used freely during usual working hours, 7 am to 7 pm.

Nighttime airboat operations may be impacted. We believe that most airboats are too loud to operate overnight and early morning in estuaries that are surrounded by residential neighborhoods and campgrounds. However, if an airboat can be equipped and operated to meet noise limits prescribed to other watercraft (i.e. 75 dbA as measured at 50 feet) we would support its right to operate at any time of day. Alternatively we would support the creation of noise sensitive zones to restrict night operations in sensitive areas while allowing operation in other areas, provided there is adequate local input on creation of these zones. The result of either a reasonable nighttime sound limitation or the establishment of noise sensitive zones may impact the ability of some operators to run airboats in the early morning hours. This is not the goal of CAAN, but an unfortunate consequence of the loud nature of airboats. We wish airboats were quieter so that we could support their use at any time of day and in any location. While we want to be as accommodating as possible, we cannot support permitting industrial levels of noise in our neighborhoods at night.

Hasn't shorefront development limited land access to mudflats? Aren't airboats just helping harvesters get to their work site?

Yes. The loss of shorefront access over private land is a long term and complex problem facing harvesters and other waterfront users, and we support efforts to expand landside access to the waterfront. For example, our group submitted testimony in 2021 in support of LD 687 and LD 983, proposed bond issues to be used for acquisition of property that will, in part, expand land access to the waterfront. We will continue to support similar efforts.

Undoubtedly, airboats make access to some areas more convenient, and for this reason we seek to set a standard that will allow most airboats to operate during usual working hours. However, the correct way to address waterfront access issues is not to permit unlimited noise pollution that diminishes the natural resource for residents and other waterfront users. The vast majority of people affected by airboat noise do not own waterfront property and have no fault for the decades-long decline in public access. They are simply people who reside nearby, in neighborhoods next to the Harraseeket River, Maquoit Bay and Merepoint Bay; or who sail, fish and kayak in these waters; or camp in parks along their shores. Waterfront access and airboat noise are two important but separate issues that each deserve to be addressed.

NOISE AND WILDLIFE

Is there evidence that noise pollution affects wildlife?

Yes. A systematic review of over 290 studies on the impact of noise on wildlife found evidence that higher noise levels are associated with many adverse effects including a decline in species diversity, abundance, and reproductive success for various birds and land animals.

If you have other questions please email admin@mainecoastalnoise.org.