🔍 Key Concepts

• Follow the flow of jacket cooling water from the engine outlet back to the expansion tank and see which branches have bypass lines and valves drawn around a heat exchanger. • Compare which heat exchangers are clearly serving main engine essential functions (must be in use at any power) and which serve auxiliary or at‑sea only loads. • Think about what changes when maneuvering in port (low power, low exhaust temperature, turbocharger not working hard) and which coolers are mainly needed at high, steady sea load.

💭 Think About

• On the diagram, which numbered components are drawn as shell‑and‑tube heat exchangers that have a dedicated bypass line with valves allowing the water to go around them? • Which of those heat exchangers appear to be associated with systems that are used only at sea speed (for example, high‑load scavenge air or certain fuel oil services) rather than during short, low‑load maneuvering? • Looking at the right‑hand side (engine) versus the left‑hand side (auxiliary services), which exchangers would you never want to take out of service while the main engine is turning, and which could safely be isolated for a short period?

✅ Before You Answer

• Confirm on the legend/diagram that items 3, 4, 5, 6, 23, and 24 are actually heat exchangers, not pumps or valves. • Trace the bypass lines and isolation valves around each candidate heat exchanger and see which ones are clearly shown as being able to be cut out while still maintaining cooling water circulation. • Ask whether removing that cooler during maneuvering would risk overheating the engine itself; if it would, then that cooler should not be your choice. Focus on those serving non‑critical, at‑sea‑only loads.