Snowboarding. A growing sport that's a cross between surfing and skiing is the hottest thing on the slopes

WHATEVER the season, Chris Mollelo tucks a board under his arm and spends his spare time riding on it. In July when surf's up, he's catching waves on the Atlantic. In March, when the mountains here are blanketed in thick drifts of whipped-cream white, he's ``catching some air'' on a snowboard - the newest of the made-in-America board sports.

The board itself resembles a surfboard, but it has straps and supports in which the snowboarder places his feet. Then he hunches into position and slides down the slope, standing sideways and bending at the hips to control direction.

Mr. Mollelo and two other snowboarding instructors were huddled in a heated shelter at the foot of Stratton Mountain recently, taking a break from their classes and the biting wind and chatting with a reporter.

``I really prefer snowboarding to skiing,'' said Mollelo. ``It's freer, more natural. There's less strain on your body. And it's a lot less expensive.

``To ski, you have to shell out about 250 bucks for a good pair of boots, 100 bucks for bindings, $40 for poles, and about $350 for a good pair of skis. That's about 750 bucks right there. A snowboard will cost you between 149 and 400 bucks. And you don't need special boots, just high ones like those,'' he said, pointing to my well seasoned L.L. Bean Maine hunting boots.

``And it's not hard to learn. You fall a lot to begin with, but in two or three days you can get to be really `hot.'''

``It's a lot easier to learn than skateboarding,'' added Austrian-born snowboarding whiz Marianna Fruhmann. ``It hurts when you fall on cement.''

First-cousin to the surfboard and skateboard, the snowboard is the grown-up version of the ``Snurfers'' youngsters have been using in the snow for about 20 years. The snowboards are sleek instruments of moulded fiberglass and eye-popping graphics. Though the idea has been around for several decades, it wasn't until the 1970s that boards began to attract serious attention. Seventy-five percent of the ones now in use come from the Burton Corporation in Manchester Center, Vt., which has been making them since 1978. Today's boards can do a hot 60 mph.

Not all skiers take kindly to sharing the slopes with speeding snowboarders, however, even though a ski racer can actually go twice as fast, by getting down in tuck position. Mollelo and others who've tried snowboarding, though, find that their skis now collect dust in the garage.

Enthusiasts estimate that about 25 percent of the ski areas have opened their trails to snowboarders. But it's not just a matter of picking up a board and hopping on a lift. ``You have to be certified,'' explained one young woman in a purple skin-tight spiderman outfit. ``You have to pass a test to prove you can do it. Only then are you allowed on the trails. Skiers don't even have to do that.''

According to Suzie Rueck, about 17 out of 180 resorts are now offering snowboarding lessons, and the figure is growing fast. Last season Stratton Mountain sold about 7,000 lift tickets to snowboarders.

But is snowboarding just a flash in the pan? Will interest melt away like Frosty the Snowman?

``Look,'' said Ms. Rueck, ``France is holding the winter Olympics in 1992, and the host country can nominate two new sports. There's a rumor that snowboarding could become an Olympic event.''

An international competition here at Stratton Mountain March 6-8 drew over 200 competitors, including a few from Japan and Australia. Craig Kelly of Dillon, Colo., and Eveline Dwirth of Switzerland won the men's and women's slaloms, and James Klassen of Calgary, Alberta, and Lori Gibbs of Encinitas, Calif., won the men's and women's downhill. Most of the competitors were people in their late teens and early 20s. In fact, it would be easier to find a snowball in Miami Beach than to find a snowboarder over 30 at Stratton.

Most skiers I talked to hadn't yet tried snowboarding, but almost all the younger folks said they would try it before the season is over.