Over fort walls

A spear flew past her ear. The Argo II was already pulling away from the dock. Piper was at the gangplank, her hand outstretched.
Annabeth leaped and grabbed Piper's hand. The gangplank fell into the sea, and the two girls tumbled onto the deck.
"Go!" Annabeth screamed. "Go, go, go!"
The engines rumbled beneath her. The oars churned. Jason changed the course of the wind, and Percy called up a massive wave, which rifted the ship higher than the fort's walls and pushed it out to sea. By the time the Argo II reached top speed, Fort Sumter was only a blot in the distance, and they were racing across the waves toward the ancient lands.

MoA ch.20