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Jet Skis, which send their adrenaline-seeking riders skimming atop the surf at 60-plus mph are also sending them — or anyone who gets in their way — to the morgue.

The tragic accident that left the 11-year-old stepson of R&B star Usher brain dead, and the death of a retired astronaut from a similar collision are raising warning flags and prompting critics to complain that it's just too easy for a careless or untrained thrill-seeker to hop on a personal watercraft and go racing along congested waterways or shores.

“It’s somewhat of a perfect storm,” said Ron Sarver, deputy director for the National Association of State Boating Law Administrators (NASBLA). “There’s been a number of accidents together here, so we have a lot of people saying, ‘What’s happening?’”

The best known personal watercrafts are Kawasaki's Jet Ski, on which riders stand, and Yamaha Motor Company's WaveRunner, where they sit. But there are dozens of brands of the personal watercrafts, and Americans own an estimated 1.3 million of them.

As of Wednesday, a total of 16 people nationwide were killed on personal watercraft, according to U.S. Coast Guard statistics, with 212 injuries tallied in 238 accidents. In 2011, some 44 people were killed on personal watercrafts, up from 38 a year earlier. With so many in use, accidents will inevitably occur, but given the high speeds and limited protection offered by the vehicles, riders sometimes don't walk away.

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Kristin Beale, of Richmond, Va., endured countless hours of physical therapy since Aug. 28, 2005, when she was struck by another Jet Ski while riding one with a friend on Lake Gaston in North Carolina. Her close friend Mark Brennan, 16, died and Beale, then 15, suffered traumatic injuries to her spinal cord and brain. Beale, like some safety advocates in the industry, now "strongly believes" there should a separate license requirement for personal watercraft and a minimum age for operators.

"And you should be trained on a Jet Ski if you're going to drive that," Beale told FoxNews.com.

Rules for riding vary from state to state, but for private owners, there is very little opportunity to enforce regulations. And on beaches where waverunners can rent for $95 an hour or more, showing you're at least 16 and yawning through a boilerplate safety lesson is all that's needed to mount the device and take off.

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Usher's stepson, Kyle Glover, was reportedly hit by a family friend on a Jet Ski on Georgia’s Lake Lanier on Friday as he sat in an inner tube. He remained in critical condition as of late Tuesday, according to the Atlanta Journal-Constitution, while sources told TMZ that no brain activity had been seen since his hospitalization.

Just days earlier, on July 1, former astronaut Alan Poindexter was riding on a Jet Ski with his 22-year-old son when his 26-year-old son crashed into them. Poindexter, who piloted the Atlantis space shuttle in 2008, died a short time later at an area hospital. Zachary Poindexter and his brother Samuel were not injured. Last year, pop-reggae star Sean Kingston was critically injured in May 2011 after crashing his personal watercraft into a Miami Beach bridge.

While those accidents have garnered headlines, there have been several other notable wrecks involving personal watercraft:

— Blair Holliday, a sophomore wide receiver at Duke University, suffered head injuries while using a Jet Ski in North Carolina on July 4 and reportedly remains in critical condition;

— Savannah Cayce, 16, of Juneau, reportedly died in June from injuries she sustained while being struck by a Jet Ski as she sat in an inner tube in Alaska’s Auke Lake;

— Three women were killed and four others were reportedly injured during an accident in October involving a Jet Ski and a 20-foot powerboat at Puddingstone Reservoir in San Dimas, Calif.

Sarver's group is pushing states to require operators of all watercraft to be at least 16, take mandatory education sessions and to require life jackets for all riders, Sarver said. Some 44 states require some form of mandatory education, with states like California, Alaska and Wyoming being notable exceptions.

“It’s kind of scary that anybody who has the money can go out and buy a boat and be on the water that afternoon,” Sarver said. “You’ve got this big machine out there that can do some harm. We want people to be out there, but now more than ever, we need for people to be educated.”

In Florida, for example, there are additional regulations specific to personal watercraft, including that operators must be at least 14 years old, must wear a life jacket and must be able to use an engine cut-off switch. Riders can also only ride the watercrafts during daylight hours and cannot operate them recklessly, said Katie Purcell, a spokeswoman for the Florida Fish and Wildlife Conservation Commission.

Elsewhere, in Texas, all equipment requirements for regular motorboats also apply to personal watercraft, as well as mandatory usage of life jackets and engine cut-off switches, if applicable. Children under 13 are prohibited from operating them unless accompanied by an adult, and no personal watercraft is allowed within 50 feet of another vessel, person or object.

Children, Sarver said, should only ride personal watercraft if they’re big enough for the vessel — no exceptions.

“Their feet must reach the bottom of the vessel,” he said. “I’d like to say that’s common sense, but common sense doesn’t seem so common anymore.”

Much like operating a big rig on a bustling highway, a marine safety expert contacted by FoxNews.com said education and preparedness go a long way.

“Knowing the rules of the road, so to speak, are very important in improving the safety of people using personal watercraft,” Marjorie Murtagh Cooke of Robson Forensic said. “They’re powerful watercraft and you need to know not only how to operate them, but how to operate them safely.”

Meanwhile, in Nags Head, N.C., thrill-seekers can ride a Jet Ski for $95 an hour at Kitty Hawk Water Sports, where all riders must wear a life jacket and undergo a safety session prior to hitting the wake. To operate a Jet Ski, riders must be 16 years old and possess a valid driver’s license. There’s also an employee patrolling the water at all times.

“But any age can ride,” an employee told FoxNews.com.

Beale, meanwhile, was determined to make sure her accident didn't define her life. After months of rehab, she returned to Deep Run High School and graduated from Randolph-Macon College in May. She now hopes to attend graduate school to become a clinical psychologist.

"I don't regret one thing about it," Beale told FoxNews.com of her accident. "It's actually been the best thing that's ever happened to me. It gave me a purpose, a story. And it just completely turned my world around."

Using a walker and leg braces, Beale manages to get around but she's determined to walk again — something her doctors said was an impossibility seven years ago.

"I have no doubt in my mind that I'm going to be walking again," she said. "I'm already halfway there."