SHIP IMPACT STUDIES

Abstract

A major role of the naval architect is assessing the value of future equipments and costs of requirements to the Navy. The means of doing this is a series of ship feasibility studies. Setting R&D priorities or establishing the requirements for a new ship class often means 40 to 100 of these studies. The paper presents, in an appendix, the titles of a sample series of impact studies from the early stage design of the DDG-51: 7 baselines with a total of 52 excursions. The amount of work is so demanding that the nature of the process itself is often obscured by the massive amount of output. There is no “universal” system impact; the ship impact assigned to something is dependent on a series of factors. It depends on what baseline ship is chosen, if the ship is near a machinery step function, in what order the questions are asked, what the subsystems of that ship are, whether a knee in the curve has been reached, fleet operational preferences, the fact that savings are not cumulative and inherent flaws in the process. The paper discusses how changes in basic ship architecture alter the results of ship impact studies. A second appendix describes three generations of destroyers (CL-51, DD-963 and the DDG-51) of similar displacement but with radically different ship impact responses. The variable nature of ship impact results is why “savings” of systems which are widely advertized in technical society papers and new-system-advocate pitches are sometimes not found in procurement ship studies. The users of the ship impact studies (the OpNav requirement writers and the R&D investment selectors) should understand the strengths and weakness of assessing ship impact. They should also understand the need to prepare design tools in advance and the need to study the impact on future ship concepts rather than existing ships.