"It's not as simple as that," she responded. "There must be room on either side."

"Room for what?" he asked.

"For the currents," she replied, moving back to the centre of the boat.

"I thought the currents just pushed us along?"

"And where, do you suppose, these currents would come from?" Natalia asked.

"I assume from behind us," he responded, "where else?"

"I can't just pull currents from the middle of nowhere," she explained. "When water moves, other water fills in behind. I'd have to affect water for hundreds of miles to make that work."

"Then where does it come from?" Athgar asked.

"Either side of the ship," she said. "If you imagine a whirlpool and then you drop a stick into the outside of it, what would happen?"

"The stick would be pushed along the outside of the whirlpool, wouldn't it?"

"Precisely," she continued. "So what happens is that I create two small whirlpools, moving in opposite directions to each other, placed so that our ship is directly between them. The edge of each will push us forward, but the displaced water will be replaced by the other water swirling around each pool."

"So if anyone was on the other side of the whirlpools, they'd be pushed backward?"

"Relative to us, yes," Natalia agreed. "But don't expect to see an actual whirlpool, it's really just a swirling current."

"I assume those circular currents will move along with us?" he asked.

"Of course, or else they'd be next to useless."

"Just how fast will it move us?" asked Athgar.

"I can't say for sure," she explained. "There are too many variables, that's where experience would come in handy. The smaller the ship, the faster I would be able to propel it. With a ship the size of the Swift, I rather expect we'll be moving at a sedate pace."

"Sedate?" he asked.

"Yes," she replied, "about the speed of a slow walk."

"Will that be enough to keep the pirates at bay?" Athgar asked.

"I doubt it," she replied, "so keep your eyes open for danger."

"How much energy are you going to need?" Athgar said. "I only ask because last time you exerted yourself, you ran into problems."

"It'll take more than calming a storm," she said, "but my energy has returned, I should be fine."

"Should be?" he balked. "You're not filling me with confidence."

Natalia smiled, trying to lessen his concern. "I'll be fine," she assured him, then looked along the deck, waiting for the captain to acknowledge her presence. "You should lower the sail," she said to him, "or it will hamper our progress."

Captain Runell barked out orders, and the crew scrambled up the rigging. After years of sailing together, they were quite efficient. Soon, the long canvas was rolled up and stowed along the yardarm.

"Whenever you're ready," called out the captain.