It has been noticed from tests made on a medium speed catamaran model, with central bulbs placed
between the demi-hulls [1], that resistance and motion reduction are affected by bulb size and its placing. By using small
size bulbs, moderate reductions are obtained, especially on heavier and larger hulls. By comparing the results obtained on
different displacement catamaran models, but having the same main size and the same bulbs, larger motion reductions
have been noticed on the lightest model. For this reason, it has been decided to extend the investigation on a medium
speed catamaran, by using larger central bulbs and placing also flat plate dampers on the same bulb. The results obtained
have been positive and demonstrate the effectiveness of this solution. A detailed description of the catamaran hull and its
bulbs will be reported and the most relevant results obtained from the model tests will be shown and discussed.
