How did the fleet stay white during a global voyage?

Did the Great White Fleet repaint before reaching each port?

Probably. Regular cleaning and repainting would be needed to keep the white hulls presentable after steaming and gunnery practice.

Long-distance steaming and gunnery practice would leave the ships dirty, making regular cleaning and repainting likely. The imagined routine has sailors working over the side on planks suspended by ropes. Cleaning would come before each fresh coat of paint. Keeping the fleet's white hulls presentable would demand repeated manual work between ceremonial appearances.