In the volleyball world, the Hawai'i outside hitter nicknamed "Sky" has no limits.

"He's a very good player," head coach Mike Wilton said of freshman Joshua "Sky" Walker, who had team highs of 24 and 16 kills in victories over UC San Diego last week.

Walker earned the handle because of his vertical leap of 37 1/2 inches.

"Don't forget the 'half,' " he said, laughing.

It was Walker's vertical jump and powerful swing that caught the attention of UH associate coach Tino Reyes during two California tournaments.

"We thought he could develop into a player," Reyes said. "He's got a ways to go, but he's moving in the right direction."

Walker, who was raised in Virginia Beach, Va., has played the sport only since high school — and that was a way to cross-train for basketball.

Basketball was his first love. Like many gravity-defying players, he never forgot his first dunk, as a ninth-grader.

"It was on my driveway," he recalled. "My sister threw it up. I went up, and tried to dunk it, and I got it."

During his senior year, he was presented with two options: Play for a Division II basketball team on the East Coast or accept a partial volleyball scholarship from Hawai'i. It was an easy choice.

Walker redshirted last season. This year, he started in UH's second match, but did not last past Game 1. But in the revised lineup, which was introduced last week, Walker earned a spot as outside attacker.

"Josh is an unbelievable attacker," said libero Ric Cervantes, who has to pass Walker's serves and spikes in practices.

Reyes estimated Walker's spikes can travel up to 70 mph. But over a short distance (a volleyball court) and sharp angle (he can touch 11 feet 4), Walker's shots are "pretty fast," Reyes said.

"It is fast," Cervantes said.

Even when Walker mis-hits, when the shot has no top spin, "it doesn't mater," Cervantes said. "He hits the ball down pretty hard. He's going to keep developing. I've got a lot of faith in him."

When Walker is not in the gym or a classroom, he can be found in the Nagatani Academic Center.

He aspires to be a civil engineer, a career path that was launched when he completed a computer-aided design program in high school.

He also is enrolled in business classes this semester.

"I'm interested in that, too," he said.

He hopes to keep up with his studies during this week's road trip.

The Warriors practice this morning, then depart this afternoon for road matches against UC Santa Barbara Friday and Saturday.

Reach Stephen Tsai at stsai@honoluluadvertiser.com.