Drowning
in Noise

Noise Costs
of Jet Skis
in America

Executive Summary

A Report for the
Noise Pollution
Clearinghouse

by Charles Komanoff
& Howard Shaw, Ph. D.

APRIL 2000

Disclaimer

“Jet Ski” is a registered trademark of Kawasaki Motors Corp., U.S.A. In this report we use “jet ski” (in lower case) to denote a generic class of watercraft that is popularly known and commonly referred to by that term. We do not mean to single out Kawasaki for criticism, nor do we assert or imply that Kawasaki’s products are noisier than those of their competitors.

The term “personal watercraft” is often used interchangeably with “jet ski,” particularly in legal and regulatory contexts. However, “personal watercraft” is in some respects a misnomer, since jet skis increasingly are designed to carry two or more people. In addition, many non-motorized craft usable by one person, such as kayaks, canoes, small rowing shells and windsurfers could (perhaps even more aptly) be characterized as personal watercraft. (Note that “windsurfer,” which we use generically here, is also a trademark when capitalized.) Another term seen in this context, “thrill craft,” is inappropriate for this report because it includes other ultra-fast boats.

The term “jet ski” in its generic sense is firmly established in popular usage. See, for example, Time magazine (June 14, 1999), the New York Times (Sept. 16, 1998), and LakeLine magazine (June 1994), among many others. In the New York Times article cited, it was noted that personal watercraft are “commonly known as jet skis,” and that term was used in the headline. We continue in that vernacular tradition.

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1. Summary of Findings

Context. People don’t like noise and will pay to avoid it; witness the reduced market value of houses near airport runways and highways. In this report, we estimate, in quantitative terms, just how annoyed beachgoers in the United States are by the sound of jet skis(1) operated nearby.

We do this through a quantitative model that estimates the monetary value of the “disamenity” (lost enjoyment) that jet ski noise introduces into beach environments in America. Our results, expressed in dollars, are what beachgoers would pay to rid lake, bay, river and ocean beaches of jet ski noise — if there were an entity that would take their money and turn off the noise.

We present two types of estimates: the “annoyance” cost of jet ski noise itself, and the effectiveness of possible strategies to reduce this cost. Other social and environmental costs of jet skis, such as water and air pollution, harm to swimmers and wildlife, etc., are discussed in Section 9, but only summarily; our subject here is jet ski noise and its cost to beachgoers.

Estimates of Jet Ski Noise Costs

National jet ski noise costs: The 1.3 million jet skis in the United States impose approximately $900 million of noise costs on U.S. beachgoers each year.(2)

Noise costs per jet ski: The average jet ski imposes $47 of noise pollution costs on beachgoers in the course of a day’s use. Since the average jet ski is used 15 days a year, it imposes approximately $700 of noise costs on beachgoers each year.

Future growth in jet ski noise costs: With the number of jet skis in use growing by 100,000 a year, the total noise cost will continue to increase. Even if all jet skis sold after 2000 are substantially quieter (by 5 decibels) than current models, jet ski noise costs to beachgoers nationwide in 2005 will be approximately $1.07 billion, or 18 percent greater than the year-2000 total.

These figures do not include the noise costs (including reduced property values) to residents of waterfront areas in range of jet ski noise, or to canoeists, kayakers and other boaters, or to hikers on nearby trails. (These are noted separately on pp. 6-7.)

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Table 1: Noise Cost to Beachgoers per Day from One Jet Ski

Beach types are defined in Table 3 on p. 34.

Jet ski noise costs by beach type: We define beaches as popular, secluded or intermediate-use, based on beach-user population density; and also divide them into “lake-type” beaches (a category that also includes beaches along bays, rivers and canals) or ocean beaches. As Table 1 shows, jet ski noise costs per beachgoer are highest at secluded lakes. On the other hand, noise costs per jet ski are highest at popular beaches, since more people are affected.

Table 2: National Jet Ski Noise Costs to Beachgoers, per Year

Figures in table are derived in Section 6.

According to industry surveys, some 92% of jet ski usage is on lake-type waters, with the remaining 8% on oceans. We assume that 60% of usage is on secluded waters, while the other 40% is split equally between intermediate-use and popular water bodies. With these assumptions, the total national noise cost to beachgoers from jet skis is

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just over $900 million a year. As Table 2 shows, roughly half of the total is experienced on popular lakes, one-fifth is on intermediate lakes, 15% is on popular ocean beaches, and 12% is on secluded lakes. All lake-type beaches (lakes, bays, rivers and canals) bear $732 million in jet ski noise costs, or 81% of the total.

Why Jet Ski Noise Is So Annoying. Jet ski noise is different from that of motorboats. The heart of the difference, and the crux of the jet ski noise problem, is that jet skis continually leave the water. This magnifies their noise impact in two ways.

First, minus the muffling effect of the water, the jet ski engine’s exhaust is much louder, typically by 15 dBA. As a result, an airborne jet ski has the same noise impact on a listener at the water’s edge as an in-water jet ski 8 times further away, or the same as 32 identical in-water jet skis at the same distance.

Second, each time the jet ski re-enters the water, it smacks the surface with an explosive “whomp” — sometimes with a series of them.

Leaving the water is central to the fun of jet skiing; for many jet skiers, the ultimate thrill is to take to the air and bounce off the water repeatedly. But jet skis don’t have to deliberately jump to leave the water. Because of the short hull, a jet ski ridden fast on even a slightly choppy surface will lift out of the water naturally, eliminating the water’s sound-muffling action and creating that jarring whomp.

And that’s not all. The direct noise-amplifying effect of leaving and re-entering the water is compounded by the variable nature of the noise. Rapidly varying noise is much more annoying than constant noise, as decades of psycho-acoustics research have established. A varying noise commands the hearer’s continuous attention, making it especially bothersome. This phenomenon has been largely overlooked in the jet ski controversy. We have quantified its effect here, enabling us to capture the full and unique impact of jet ski noise.

Strategies to Reduce Noise Costs. Three broad approaches have been suggested to reduce jet ski noise costs to beachgoers:

• develop quieter jet skis;
• require jet skis to operate further from shore;
• restrict jet ski usage to fewer bodies of water.

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We have found that only the third approach — restricting usage — holds real promise for significantly reducing jet ski noise costs in a region or nationwide. (Banning “wake-jumping” is infeasible; see Section 8. Taxing users for jet skis’ environmental damage is discussed further below. “Temporal segregation” is treated briefly in Section 8.)

We estimated the measures necessary to reduce nationwide jet ski noise costs to beachgoers by three-fourths from today’s levels by the year 2005, while assuming that the number of jet skis in use will rise from 1.3 million to 1.8 million. Meeting this goal would require banning jet skis from 90% of all U.S. lakes, bays, rivers and oceans.

Alternatively, the same objective can be met by banning jet skis from 82% of waters, and requiring jet skis at the remaining sites to operate at least a quarter-mile from shore. (If the half a million jet skis projected to be purchased between now and 2005 are 5 decibels quieter than current models, on average, then the 82%-complete ban could be relaxed slightly, to a level of 78%.)

By themselves, “minimum-distance” laws will not cure the problem of jet ski noise to beachgoers. We estimate that barring jet skis from operating within 500 feet of shore would reduce nationwide noise costs from current jet skis by only 27%; moreover, this improvement would be wiped out by growth in usage in five years. Even a quarter-mile rule would only reduce current jet ski noise costs by 48%, and by 2005 this reduction would be trimmed to 28%.

Perhaps surprisingly, the introduction of quieter models will not reduce total jet ski noise costs at all. Even if every new jet ski sold after 2000 were built with modified engine designs that some manufacturers claim reduce noise emissions by 5 decibels, the national jet ski noise cost to beachgoers in 2005 would still be 18% greater than today, according to our calculations. Because they apply to new models and not to jet skis currently in use, technological refinements to make jet skis quieter will not lessen the absolute burden to beachgoers, nor even prevent that burden from growing.

Taxes on jet ski noise: Another approach to reducing jet ski noise costs is to “internalize” them by taxing their sale or use. We estimate that a tax rate corresponding to just half of a typical jet ski’s noise costs would drive up the purchase or rental price to an extent that a third of all jet ski use — and noise — would be eliminated. Higher

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taxes capturing a larger share of jet ski noise costs, as well as their pollution and injury damage to humans, wildlife and marine ecosystems, would eliminate larger fractions of jet ski use and noise.

Substantially reducing noise costs of jet skis requires banning them
from most waters, and mandating that they stay at least a
quarter-mile from shore at remaining areas.

Jet Ski Costs Apart From Beachgoers

Non-beachgoer noise costs: Using the framework developed here to estimate jet ski noise costs to beachgoers, but employing rougher estimates for some key parameters, we have estimated that jet ski noise costs to owners of waterfront property in the U.S. are on the order of $230 million a year; similarly, jet ski noise costs to non-motorized boaters (e.g., canoeists, kayakers, and windsurfers) are on the order of $120 million annually. These figures are not included in the noise costs to beachgoers given above.

Other costs of jet skis: After reviewing the literature on both jet ski emissions and the health costs of air pollution, we have estimated that air pollution from jet skis imposes at least $240 million a year in health costs to Americans. Other costs from jet skis, including

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pollution of marine environments, habitat and wildlife destruction, and endangerment and injury to humans, are mentioned but not quantified later in this report. These costs are treated in Section 9.

National jet ski noise costs to beachgoers are now over $900 million
and could reach $1.25 billion in 2005 (see Section 6). Noise costs
to property owners and water recreationists are estimated roughly
in Section 9.