Development of Intact Stability Calculations Tool for Ships

Ship stability has long been a major concern for ship builders, ship operators, and regulatory bodies in the field of naval architecture. Ship commands are always concerned about the state of ship stability in loaded conditions before embarking on a cruise as it changes throughout a trip due to different operations onboard and changing weather conditions. To predict ship stability with varying loading conditions, ship command is provided with stability booklet which require skilled operators and is labor intensive; that is time consuming and may be subject to human errors. Furthermore, the commercial software’s available to assess ship stability are computationally expensive and demand high specifications for its use making it incompatible to integrate with existing onboard systems. So, this research aims to develop a tool on Microsoft Excel using visual basic to automate the stability calculations process and to make these calculations faster and reliable helping ship command to take best course of action in maintaining ship stability in sea. The tool will enable ship command to predict ship stability by computing ship hydrostatic data, cross curve of stability (KN Curve), static curve of stability (GZ Curve) against large angle and different intact stability criteria under different operations and changing weather conditions. The data for these calculations is initially provided from the ship stability booklet and then interpolated by the tool to calculate the required values at all operational ranges. A user- friendly interface has been created utilizing the Visual Basic for Applications (VBA) language to give maximum user comfort and an intuitive working environment. The results of the tool were compared with stability booklet, and it was found that the error between interpolated results and those from booklet were less than 5% at most. The tool was demonstrated to senior naval personal and received nod of approval for integration onboard ships.