The effect of wing wall geometry and well deck configuration on the stability characteristics of amphibious landing ship dock (LSD) class ships

Amphibious ships, configured with floodable well decks, present a unique challenge to the Ship Design Team to incorporate maximum troop, cargo and vehicle capacity, along with sufficient well deck size, to facilitate efficient operation of LCAC (Landing Craft Air Cushion) and other amphibious assault craft in support of power projection operations. Analysis of the various LSD 49 Class alternative designs, revealed significant variance in the stability limits for each design. These variations appeared to be directly attributable to wing wall size, as well as to the geometry of the well deck. In order to better understand the effect of these items, and to develop guidelines for future design efforts, this study concentrated on evaluating the stability limitations for various combinations of beam, well deck configuration, and wing wall size using an LSD 49 Class proposed hull form. The results indicated that the most significant parameter affecting the stability of the LSD 49 Class is the height of the well deck above the baseline. The higher the well deck, the smaller the loss of waterplane inertia caused by the entrance of flooding water into the well deck compartment. For lower well decks, the loss of waterplane inertia is more critical at smaller values of beam, but becomes less critical at the upper values of beam considered. In these cases, off-center wing wall flooding becomes more critical, and it is more advantageous to devote larger percentages of beam to the well deck compartment.