The Voyage of the Vigilance — Garry Kilworth

Woodworld is a lodestone world, a planet with a magnetic field so strong that it can pluck spaceships out of the sky. Which is exactly what happened to Maxy, the youngest cadet in the space fleet. Stuck on Woodworld, with little hope of ever being rescued, Maxy must rely on his friends to have any chance of escape. When one of them is taken captive by Maxy's one-time companion, Baker, he has no choice but to set off in pursuit across the Electric Ocean.