Effect of propeller phase angles on the vibration response of a twin-screw super-yacht

Propeller-induced hull excitation is one of the most important causes of the vibration levels experienced in the habitable decks of ships. A reliable assessment of on-board vibrations during the early stage of ship design requires the development of practical and efficient numeric techniques. This paper studies the influence of different phase offsets between the two propeller-induced forces on the vibration responses on the deck floors of a 54 metres super-yacht. The two propeller-induced hull forces are evaluated via the Holden Method and calibrated utilizing full-scale vibration measures. Hence, the tuned forces are applied to a FE model of the vessel by progressively shifting their relative phase angles. A series of FE linear dynamic analyses are performed to estimate the vibration levels on different deck zones on the ship. The outcomes of the simulations point out remarkable divergences between the vibration levels on the deck areas, when different propeller phase angles are implemented