289. To stop the rotor of a main turbine while underway at sea you should __________.

To safely stop a main turbine rotor while underway, astern steam should be admitted after securing ahead steam. This controlled braking prevents coasting and windmilling, which can damage bearings and gears; a Prony brake is a test stand device, stern tube packing adjustments are unrelated to turbine braking, and simply securing all steam allows uncontrolled rotation.