If you think of them as waterborne motorcycles, you'll come fairly close to understanding both the great popularity and the criticism that continues to swirl around the machines that are known collectively as "personal watercraft."

The growing number of people in Orange County who ride these sit-down powerboats with handlebars praise them as affordable, sporty, quick, highly maneuverable, exciting and just plain fun.

Some other county boaters and waterborne law-enforcement officials, however, can be less-enthusiastic. Boaters complain of reckless riders violating marine-safety rules and ruining a usually calm environment with high-decibel engine noise. Orange County Harbor Patrol officers say accidents involving personal watercraft, sometimes resulting in serious injury, are on the increase in county coastal waters.

In California, personal watercraft can legally be operated by anyone age 12 or over (or younger if someone 18 or over is aboard), and no training or license is required.

In short, they are easy to own, easy to operate and, in the hands of the inexperienced, sometimes easy to crack up.

And they are very popular. Last year, the 17,142 registered personal watercraft in Orange County represented nearly a quarter 23.9% of all registered vessels.

Statewide, the percentage is 13% of registered vessels. But the 257 accidents reported last year accounted for 36% of the state's boating mishaps. There were seven fatalities.

In Orange County, Sheriff's Harbor Patrol Lt. Dick Olson said there have been 11 accidents involving 15 personal watercraft through July of this year.

"Most of those accidents resulted in some type of injury," he said. "It's just this year that we've started to have problems."

Harbor Patrol Sgt. Howard Mol said the total is certain to rise this year as more and more boaters put to sea astride personal watercraft. The vessels are particularly popular--and the accident rate higher--at Dana Point Harbor than other county coastal areas.

"It's so popular [at Dana Point Harbor] because of the short distance of the launch ramp from the ocean. The speed limit in the harbor is 5 m.p.h., but they can be out of the entrance channel and into the ocean, where they can go faster, in a matter of minutes."