Final answer:
To safely re-board a PWC, roll it over in the direction indicated by the label on the back of the vessel, to avoid engine damage.
Step-by-step explanation:
To re-board a PWC (Personal Water Craft) if you fall off, you should roll it over in the direction indicated on the back of the vessel. This direction, either clockwise or counter-clockwise, is marked to prevent damage to the engine. When overturning a PWC, be mindful of the proper technique as it is crucial for both safety and maintenance purposes.