Investigation of the Effectiveness of an Antipitching Fin and Fin Strut Combination on the Mariner

The presence of an antipitching fin attached at the hull baseline is known to cause severe hull vibrations. Two conditions thought to contribute to this problem are the collapse of the deformed wave surface profile above the fin and by fin re-entry after a bow fin emergence. An experimental investigation was conducted to determine the effect of increased strut length in reducing these conditions on a MARINER model equipped with an antipitching bow fin. Analytical predictions were also made to determine the effectivess of a bow fin in reducing the pitching motion of the MARINER hull in a seaway. The reduction in the pitching motion resulting from the addition of the bow fin to the MARINER hull, as is indicated by the analytical investigation, is not considered significant as the motion is not excessive without the antipitching fin.