Includes supplementary material. / CAPSTONE PROJECT REPORT / System Engineering and Analysis Cohort 18A and Temasek Defense Systems Institute / Approved for public release, distribution unlimited / The aging Whidbey Island and Harpers Ferry class ships, LSD-41 and 49 respectively, comprise just over one third of the amphibious navy. However, a solution to the capability gap created by the loss of these ships is needed to maintain the effectiveness of the amphibious fleet across a broad spectrum of mission areas. This research effort considers future ship designs and fleet architectures to meet the capability gaps left by the decommissioning of the LSD-41 and 49 class ships. With respect to lift capacity, performance capability, cost and a risk assessment, the analysis showed the LPD-17 or a LSD(X) approximately 30% larger than the existing classes to be acceptable replacement classes. This analysis also supports further research to determine the most robust fleet architecture apart from the current eleven LHA or LHD, eleven LPD and eleven LSD paradigm.