🔍 Key Concepts

• Heat transfer in keel coolers vs. raw water coolers (how each system rejects heat to seawater) • Effect of cooler surface area and flow path on lube oil temperature • Relationship between system design (closed keel cooling vs. direct raw water) and normal operating temperatures

💭 Think About

• Think about how a keel cooler removes heat compared to pumping raw seawater directly through an oil cooler— which setup typically has more effective, immediate cooling? • Consider whether keel-cooled systems usually run engine jacket water a bit warmer or cooler than raw-water systems, and how that trend might logically affect reduction gear lube oil temperature. • Ask yourself: if a system cools more gently/indirectly through the hull, would you expect the lube oil to run cooler, hotter, or about the same as a system with direct cold seawater flow?

✅ Before You Answer

• Compare the efficiency of direct raw seawater cooling versus indirect keel cooling for removing heat quickly. • Recall typical normal operating temperature ranges (not exact numbers, just the trend) for keel-cooled versus raw-water-cooled machinery. • Make sure the choice you pick is consistent: if temperature trend changes, does it make sense that pressure would or would not change in the same way?