🔍 Key Concepts

• Keel cooler function – how it removes heat from the engine’s jacket water (or coolant) to the surrounding seawater • Effect of fouling/insulation on heat transfer surfaces (barnacles, algae, marine growth) • Difference between raw water systems and closed jacket water cooling systems on a diesel engine

💭 Think About

• Think about what the keel cooler is actually cooling: which fluid from the engine is flowing through it? • If the outside of the keel cooler tubes is coated with marine growth, what happens to heat transfer? Does the fluid inside get hotter or colder? • Which one of the answer choices is directly related to the engine coolant that circulates through the engine block and head?

✅ Before You Answer

• Identify which system uses the keel cooler directly: jacket water (engine coolant) or raw water intake? • Consider whether fouling would cause reduced heat transfer and therefore higher temperatures in the fluid inside the cooler. • Check if a thermostat would fail mechanically from fouling outside the keel cooler, or if it would more likely respond to changes in coolant temperature.