The ability to predict ship motions has become increasingly important over the last several years. This is especially true when considering the number of recent ship designs with unconventional hull forms (i.e., Small WAterplane Twin Hull (SWATH), Surface Effect Ship (SES), etc.). Consequently, the necessity to predict ship motions by calculating the gyradius of the ship in the early stages of a ship design has become essential. The once valid method of using ""rules of thumb"" based on historical data has come into question and is considered unreliable for unconventional hull forms. Instead, the ability to calculate gyradius using the weight estimate is considered an effective and efficient way to accomplish this. Therefore, a Plan of Action and Milestones (POA&M) to develop the design tool to calculate gyradius was initiated. The focus of this effort was to modify the Ship Design Weight Estimating (SDWE) family of programs. The modifications to the computer programs result in the ability to calculate weight moments of inertia for roll, pitch, and yaw (in air) and ultimately in the calculation of the gyradius of the ship in air.