"向舷外转" can be translated as "turn outboard" or "veer outboard" in English, depending on the specific context and the degree of formality required.
"Turn outboard" is a straightforward and commonly used expression in nautical or maritime contexts, indicating a movement away from the ship's side towards the open sea or air.
"Veer outboard" could also be used, though "veer" might imply a more sudden or unexpected change in direction. In many cases, "turn outboard" would be the more appropriate choice.