Jet Skis and other "personal watercraft" are becoming more and more popular in Hawai'i as a cheaper alternative to buying a boat and one that needs less maintenance. They also are proving more versatile than just a fun way to zip around on the ocean at speeds of more than 50 mph.

People use them for tow-in surfing, trolling and spearfishing, scuba diving, and even interisland travel.

"It's doable, but not recommended," said Shawn Beckwith of Cycle City in Honolulu, the state's main dealer of Kawasaki Jet Skis, which sell for $6,000 to $12,000.

Beckwith said there's been a "huge upswing" in Jet Ski sales in the past two years, although he declined to provide sales figures.

The Department of Land and Natural Resources reports that about 1,700 thrillcraft are registered in the state, a 63 percent increase from five years ago. The state defines "thrillcraft" as any motorized vessel that is generally less than 13 feet in length, uses an inboard water jet pump for propulsion, is capable of exceeding 20 mph, and is designed to be operated sitting down, standing or kneeling. These include Jet Skis, Yamaha WaveRunners, Sea-Doos, "wet bikes," surf jets and similar craft.

Thrillcraft owners prefer the more respectable term "personal watercraft," or PWC.

Michael Spain of Waiakea on the Big Island said PWC operators have gotten an undeserved outlaw reputation for recklessness and daring. At Hilo Bay "it's a family sport," with friends gathering every weekend to pitch tents on the beach and barbecue while parents take their kids out for a ride or tow on a sled or inner tube.

Spain, 42, who works as director of adolescent services for the Big Island Substance Abuse Council, owns two Jet Skis and loves the "freedom we get out on the water." Thanks to the family hobby, Spain said, his 8-year-old son and two daughters, ages 9 and 11, are well-versed in marine safety and ocean awareness.

Because of their increasing popularity, a new state rule went into effect this year requiring PWC operators to complete a certification course on thrillcraft safety. The course includes instruction in laws pertaining to protected marine species.

The program for now is available only on O'ahu through Windward Community College. PWC operators on the Neighbor Islands will get a pass on the requirement until the courses are offered there. DLNR officials said they do not know when that will happen.

Andrew Ford, a DLNR enforcement officer in Hilo, periodically holds informal meetings with PWC owners to make sure they are familiar with the rules. One such meeting is planned for today, with U.S. Coast Guard Auxiliary members providing free safety inspections.

"Two years ago there were maybe 10 or 15 regular users of personal watercraft in the Hilo area and I knew them all," Ford said. "Now there are over 100 and every couple of days I see a couple brand-new Jet Skis on the back of a truck with the sticker still on them."

Ford said many people who purchase PWCs are unaware of restrictions on how and where they can be operated. "The primary issues are operating out of authorized areas, unsafe operation, equipment violations and registration," he said.

With seven enforcement officers in the East Hawai'i District, monitoring thrillcraft is taking up "is quite a lot of time on weekends," according to Ford.

Archie Kalepa, Maui County ocean safety operations supervisor, said more people, in general, are spending time in the ocean, and personal watercraft "are an activity that's pretty attractive."

Kalepa helped pioneer use of PWC for rescue operations in Hawai'i and is an elite tow-in surfer. He said insufficient knowledge of the vessel and ocean conditions are key reasons PWC operators get into trouble.

"We get calls all the time about Jet Skis that are broken down or missing Jet Skiers," he said. "By understanding the capabilities of the Jet Ski and themselves, people can minimize the chance of being involved in a search and rescue." Kalepa also recommended checking weather and marine forecasts before heading out, enrolling in PWC or boating safety courses, and using a buddy system.

"You jump on this thing and you forget about everything. Everyone thinks they're Superman and can ride across the channel," he said.

Kalepa is one of the few expert riders who use personal watercraft between islands, including on one seven-hour trip from Maui to O'ahu.

The Coast Guard reports that PWCs were involved in only three of the 604 cases it handled in Hawai'i since the start of the federal fiscal year in October. One case occurred last month when a Massachusetts college student was knocked from a rented WaveRunner and spent 15 hours drifting in the ocean off Maui before rescue.

The other two cases were minor incidents, and no PWC-related injuries have been reported so far this year, according to the Coast Guard.

Richard Rice, state administrator of small boat harbors for the DLNR, said there have been very few complaints about recreational users. "It hasn't reached any kind saturation point yet," he said.

"People seem to be minding their manners and using common sense," Rice said. "Because it's new and just growing, we don't know where the equilibrium will be. If the public recognizes issues, I'm sure they will bring them up."

In Hilo Bay, PWCs are limited to an area about a mile long and 500 yards wide near the end of the breakwater. Other ocean recreation management areas with recreational thrillcraft zones are at Kailua Bay in Kona, and on O'ahu at Hale'iwa, Kane'ohe and Maunalua bays and the Reef Runway.

In the management areas without designated thrillcraft zones, operators must stay at least 500 feet from shore or from the outer edge of the reef, whichever is greater.

Personal watercraft regulations vary from island to island, and use in some areas around O'ahu, Maui and the Big Island is prohibited from Dec. 15 to May 15, when humpback whales are present. For more information, check with the local Division of Boating and Ocean Recreation office or visit the division's Web site at www.hawaii.gov/dlnr/ dbor.