🔍 Key Concepts

• closed freshwater cooling system purpose and operation • differences between freshwater (jacket water) and raw seawater systems • why engine manufacturers like to keep engine metal surfaces at a stable temperature

💭 Think About

• Which option describes something that is actually easier to achieve when the engine has a dedicated loop of treated fresh water circulating inside it? • Think about corrosion, scaling, and temperature swings: which option really matches what happens in a closed system? • Which choices sound like clear advantages—but might not be technically true for how these systems are designed and maintained?

✅ Before You Answer

• Verify how jacket water is used to control engine operating temperature and warm‑up time. • Check whether water treatment is still needed in a closed freshwater system to prevent corrosion and scale. • Consider which options describe features that are not unique to closed freshwater systems (could they also apply to other systems?).