If a vessel is to be laid up for an extended period of time with minimal utilities provided from ashore, what statement is true as it relates to keeping gearboxes, turbine casings, and engine crankcases dry and free of moisture?

Correct Answer: Option A — A combination of mechanical circulation of air and dehumidification should be used.

Preventing corrosion in idle machinery requires controlling the internal environment. Mechanical air circulation ensures uniform distribution of dry air, while dehumidification removes moisture from the atmosphere. This combination prevents condensation on internal surfaces, protecting critical components like turbine casings, gearboxes, and crankcases from oxidation during long-term vessel lay-up.