No word was spoken, and only the most shaded lamp was used, casting a tiny bar of light whenever Plank raised the shield. He led his hooded visitor onto the most sluggish of the former warships. He dismissed the watch and took the King down into the belly of the ship, one deck above the bilge.

Then Plank lifted a hatch, handed the lantern to the King, and plunged down into the bilgewater. Rats squealed and scurried, but Plank paid them no attention. “Cast the beam here,” he said softly.

The King raised the shield and aimed the beam at Plank’s hands. Plank gripped a lever that was snugged up under a deck joist and pulled it toward himself, moving it through an arc that was one-eighth of a circle. Where the lever had been invisible, now it was plain to see.

“What does it do?” asked the King softly.

“This lever is attached to a baffle under the hull. When the lever is parallel with the joist, the baffle is extended. It catches the water and makes the ship move slowly and awkwardly. It’s a home for barnacles. But at sea, far from shore”—he did not say, Far from the observing eyes of the Grayfolk—“a captain could send a trusted mate down into the bilge, to wade his way along the whole length of the keel, turning all these levers one-eighth of a circle, and then the baffles are drawn up snug against the bottom.”

The King nodded. He was a seamage. He understood that this would make the ship move much more smoothly through the water. The sailcloth, with its load of barnacles, would still be a drag on the ship, but it could be managed now.

“But the mate must be careful,” Plank continued. “For if he turns the levers forward instead of aft, the baffles are completely released and fall away from the ship, leaving the hull smooth and clean. That would be a tragic accident, for the ship would then move as swiftly and surely as a warship, and some might think that the treaty had been violated.”

“An awkward design,” said the King softly. “What madman would think of such a thing?”

“I fear it was my own invention, sir. I’m glad the King will never know how clumsily I obeyed his command.”

“You must be sure to acquaint every captain of this mechanism, and make sure they know which way to turn the lever,” said the King. “We would not want to find ourselves, quite by accident, with a war fleet of a hundred ships, where the treaty binds us to no more than five fighting vessels.”

“On your advice, sir, I will train the captains,” said Plank.