Time shares booming.

Hawaii's time-share industry is welcoming the 21st century with a big boom, with the loudest noises coming from the major hotel companies as they roll vacation ownership into their mix.

The big players are predicting 20 percent annual growth over the next five years.

For the pioneers such as Marriott International and Hilton, which began adding vacation ownerships to their hotel mix in the mid-1990s, time shares have proved to be a secret weapon. As the bellwether visitor-occupancy rates suffer during tough times, such as the aftermath of Sept. 11, time-share growth remains strong.

The island of Kauai is a great example, said John Blinstrub, president of Blinstrub Enterprises International, a time-share consulting company based in Orange County, Calif.

"The occupancy levels on Kauai have been running at 80 percent and higher, while the hotels [in the state] dropped to 50 percent to 65 percent for a while," Blinstrub said.

Both hotel and time-share executives say the synergy between the two validates the adage that the whole is greater than the sum of its parts.

Seeing an enormous pent-up demand for Hawaiian vacations, Fairfield Resorts Inc., the world's largest time-share company and Outrigger Enterprises, Hawaii's largest hotel company, agreed this summer to jointly market and develop a major part of Hawaii's time-share industry, projecting annual sales of $100 million within the next three years.

Outrigger's partnership with Fairfield is an example of a trend in the time-share market over the past few years, the continuation of which should lead to 20 percent annualized growth over the next five years, said Mark Wang, vice president of Hilton Grand Vacation Club Company Hawaii.

"The concept of time share as a mixed-use product is not a new idea, but it clearly has become more prominent with the advent of hotel company participation," he said. "All major brands are involved now."