CLEVELAND  This winter, Katie Spotz plans to cross the Atlantic Ocean without a sail or a motor. Through 50-foot waves and hurricane-force winds, the only thing propelling her tiny yellow boat will be Spotz’s arms pulling against two black oars.

In the small but growing sport of ocean rowing, even the smallest sail is considered cheating. So Spotz, 22, will row at least 2,500 miles without even a tarp to protect herself from the sun, lest she be tempted to use it to catch the wind.

“I never thought I could do something like this,” said Spotz, whose attempt will raise money for Blue Planet Run, a foundation that finances clean drinking water projects around the world.

“But it’s not like a rowing machine in a gym,” she said. “You just pace yourself.”

The journey from Dakar, Senegal, on Africa’s west coast, to South America is expected to take between 70 and 100 days. If Spotz succeeds, she will become the youngest person to cross an ocean in a rowboat, and the first American to row solo from mainland to mainland.