🔍 Key Concepts

• Direct-drive slow-speed diesel with fixed-pitch propeller – what happens to the shaft when the ship still has headway ("way on")? • Difference between normal stopping and emergency stopping/reversing procedures on large two-stroke engines. • Practical use and limitations of a shaft brake and starting air on large main engines.

💭 Think About

• Think about how a stopped fuel supply affects a big, heavy shaft and propeller that are still being turned by the ship’s momentum. Does rotation stop immediately or gradually? • On a large main engine, is the shaft brake designed to be used every time you stop, or mainly for special conditions (like maintenance, holding at zero rpm, etc.)? • Would engineers routinely oppose the ship’s remaining rotation with starting air in the opposite direction, or is that something reserved for specific maneuvers like rapid reversing?

✅ Before You Answer

• Compare what is standard operating practice versus what would be impractical or risky to do on every stop. • Ask yourself when a shaft brake is actually fitted and used on large direct-drive installations, and whether smaller ships always have one. • Consider whether continuously using opposite-direction starting air on every stop would be economical and safe, or if it would be used only in special cases.