Personal watercraft or jet skis are a relatively new phenomenon. Jet skis is actually a trademark name, but like Xerox, it has become a generic name for any form of watercraft that uses an inboard motor powering a water jet pump as its primary source of power. Personal watercraft are designed to be operated by a person sitting, standing, or kneeling on the hull, rather than the conventional manner of sitting or standing in the vessel. In many ways they look and are operated like a water borne snowmobile.
PWC are about 7 to 10 feet in length, weigh an average of 450 pounds without a rider and can accommodate between 1 and 4 passengers. PWC seating 2-4 people are becoming increasingly popular.
Four major companies produce PWCs, and three of them are also well known major manufacturers of snowmobiles. The four companies are Bombardier (Sea-Doo), Honda (AquaTrax), Kawasaki (JET SKI), and Yamaha (WaveRunner). The first commercially successful personal watercraft, the Jet Ski, was introduced by Kawasaki in 1974. Early versions of the PWC were designed for stand up only, but today most units are sit-down models.
The National Marine Manufacturers Association reports that 80,600 PWC were sold in the U.S. in 2003, with an average price of $8,890. Peak sales for PWC occurred in 1995 when more than 200,000 were sold nationwide. NMMA estimates that in 2003, there were approximately 1.4 million PWC owned in the U.S. A new trend is the growing interest in four-stroke engines as opposed to the more traditional two stroke models. Some 50 percent of all PWC sold in 2003 featured new-technology engines, such as four-stroke and direct-injection.
A recent survey of PWC owners found the average age was 41 years and have an average household income of $95,400. In addition, 71 percent are married, 40 percent are college graduates, and 85 percent are male.
Both speed and power among PWC is increasing. In 1998 more than 16 models have engines with 100 hp or more. Highly maneuverable and capable of speeds exceeding 65 mph, PWC are marketed as "thrill" vehicles. Common practices include weaving between vessels, jumping wakes, spinning doughnuts, and radical changes of course.
Because of the speed of operation and the tendency for “hot dogging” behavior, PWC are the only type of recreational watercraft for which the leading cause of fatalities is not drowning; in PWC fatalities, more persons die from blunt force trauma than from drowning.
One reason for the blunt force trauma accidents has to do with the operating mechanism of these machines. A PWC uses a moveable nozzle connected to a jet pump, rather than a propeller, to power the craft. This affects steering. Turning the PWC handlebars changes the angle of water exiting the jet pump but there is no steering ability without the jet pump operating. If the operator releases the throttle—a typical reaction for most users when facing an on-coming obstacle—steering ability is eliminated. Without power to the jet pump, there is little or no directional thrust.
Personal watercraft in use in 1996 represented 7.5 percent of the State-registered recreational boats, yet PWC accounted for 36 percent of the 1996 reported recreational boating accidents, 36 percent of the total number of vessels involved, and more than 41 percent of the persons injured in those boating accidents. Although PWC accounted for 16 percent of the registered vessels and 14 percent of the fatalities in California, they were involved in 45 percent of all recreational boating accidents and 55 percent of the persons injured. Collisions with another vessel made up the majority of recreational boating accidents (69 percent), and of these collisions, 71 percent involved one PWC colliding with a second.
Swimmers, other quiet type water craft users, shoreline hikers and wildlife enthusiasts complain that the high-pitched whine of PWC ruin their outdoor experience. PWC produce noise levels in the range of 85-102 decibels (dB) per unit — levels at which the American Hospital Association recommends hearing protection (above 85 dB).
Two-stroke engines run on a mixture of oil and gasoline, and discharge as much as one-third of this mixture unburned into the water. An average two-hour "thrill" ride on a PWC can dump between 3 and 4 gallons of gas and oil into the water. The California Air Resources Board also reported that a day’s ride on a 100 horsepower jet ski emits the same amount of smog-forming air pollution as driving 100,000 miles in a modern passenger car.
Besides the usual negative affects on water quality resulting from the use of two or even four stroke engines, PWC’s also can operate in shallow, near-shore marine habitat, which is inaccessible to most conventional motorboats. Wake waves from PWC can create serious shoreline erosion, creating turbidity and sedimentation problems in shallow productive waters.
In addition, PWC have more serious negative impacts on birds, including interruption of normal feeding activity and repeated displacement from nesting areas, than conventional motorboats, cars, all-terrain vehicles and pedestrians. For instance, one study found that waterfowl respond "significantly more" to PWCs compared to motorboats.