If both the shell-and-tube lube oil cooler and shell-and-tube jacket water cooler of a diesel engine are seawater cooled, what statement is true?

Correct Answer: Option D — Seawater flows through the tubes of both the lube-oil and jacket-water coolers.

Seawater is highly corrosive and prone to fouling. By circulating seawater through the tubes, maintenance is simplified, as the tube bundles can be easily removed for cleaning or replacement. The shell side, which is harder to clean, is reserved for the cleaner, non-corrosive oil or freshwater cooling media.