Pool rolling at the YMCA on Hasting Drive in Silver Spring is well into its sixth season, but there's still time left to practice - the pool makes its water available for boats and paddlers every Sunday morning until mid-March.

Pool rolling refers to the indoor practice session of trying to roll your kayak, C-1 or C-2 (decked canoes for one or two people) back upright after the boat has flipped over.

Sponsored by the Canoe Cruisers Association, pool rolling first got started in 1965 in the downtown YMCA. One active CCA member, Dick Bridge, who's been "rolling for 10 years," says, "boats were carried in through the men's locker room" because the regular entrance was too tight for the 17-foot boats. Now at the Silver Spring Y as many as 20 boats fit comfortably into the pool with no problem getting them into the heated structure. Pool rolling has also taken place in Bethesda, Northern Virginia Aquatic Center, Walter Reed and the Naval Reseach Laboratory in Anacostia.

Judging from the number of people who fill the pool on Sundays, whitewater canoeing is increasing in popularity. There is no age or sex barrier: Men and women attend, with ages ranging from 8 to 70. It's a fun sport, but it can also be dangerous. Therefore, the main objective before taking on any rapids is to learn to roll your kayak in the fast-moving water.

"If you don't know the river and temperature of the water, you aren't prepared, and it becomes dangerous," according to Tomo Kusuda, one of the instructor at the pool rolling sessions. Kusuda, who has been paddling in the area for five years, has learned her roll in the pool but still has some troble in the rapids. "Go gradually developing your skill," she says. Several sessions of pool rolling will help you gain confidence to tackle whitewater rapids.

There are volunteers and slalom division experts to help with instruction. The session manager will also provide an "introductory mini-lesson."

Pool rolling sessions are 9 to 11 Sunday mornings. The fee for adults is $3, for slalom division members $2, for juniors 16 and under $1.50. One lane of the pool is reserved for swimmers for a fee of $1.

Boats, paddles and spray skirts can be rented by calling Tono Kusuda at 942-2971 or John Beasley at 256-0564. They ask that you call before Thursday if you plan to attend.