Investigation of Effects of Activated Fins on Vertical Motion of a SWATH Ship in Waves,

摘要

Stationary stabilizing fins of a small waterplane area,twin-hull (SWATH) ship are known to be an effective device to damp the motion of the ship in waves. The feasibility of further reduction of motion of a SWATH ship by active fins is investigated in this report. The SWATH ship examined has displacement of 2400tons and overall lenght of 70 m. It has two pairs of fins,each attached to the inboard side of the submerged hull,in a canard arrangement. The analysis was carried out in the frequency domain by seeking optimum amplitudes and phase angles of fin motion in a frequency band within which the maximum vertical motion of the ship would occur. The results of the investigation revealed that the vertical motion at the midship and the aft end of the cross deck can be further reduced by 10to 20percent by activating the fins of the total projected area of about 45sq. m. in the sea states up to 5in the range of ship speed from 5to 15knots. (Author)