Vibration acceptance test

A vibration acceptance test measures hull and superstructure vibration at the sea trial against the habitability limits of ISO 6954:2000, which evaluates the overall frequency-weighted RMS velocity in normally occupied spaces over 1 to 80 Hz. Accelerometers or velocity transducers meeting ISO 8041 are placed on the decks of accommodation, the wheelhouse, and the engine-control room, and the ship is run at the service-speed and MCR conditions where blade-rate and engine-order excitation peak. The 2000 revision replaced the 1984 single-frequency band assessment with the combined frequency-weighted value. A result above the agreed limit forces a fix (propeller, balancing, or stiffening) and a retest before acceptance.