Secondary Development Based On NAPA For Ship Stability Quick Check

Ship design is a complex system,and the overall design plays an important role in the total design work,in which elementary solution is determined including main dimensions,structure type,general arrangement and lines.In the overall design stage,it is necessary to study the ship molded line and corresponding hydrostatic and hydrodynamic performance according to the actual design requirements and with reference to the relevant international conventions.At the same time,the intact stability,damage stability,longitudinal strength and freeboard should be checked based on the ship arrangement,light weight distribution and loading conditions.After these general works,the continuous optimization design is carried out to obtain a final satisfactory design.In view of the above check content,the development of a simple calculation program that is suitable for this is the focus of this paper.NAPA is a command-based ship design system developed by Finland NAPA company.It has a wide range of applications in the early stages of the ship and in the detailed design phase.The overall design is the most mature and widely used package of NAPA,including such as hull modeling,stability and strength calculations and so on.However,it is very complicated and time-consuming to use NAPA during the primary stage involving lots of designs comparison.It is necessary to develop NAPA system in order to improve design efficiency.Napa software has a strong secondary development potential.Macros and Manager are important development tools.Through the research of NAPA system,this paper integrates the overall design check content and develops a set of NAPA Manager programs,so that all kinds of check contents that need to be complicated and operated are collected under one Manager program to improve design efficiency.The main research contents are as follows:(1)The principle knowledge of the overall design of the ship is introduced in detail,the main international conventions on the overall design of the ship are studied,and the important parameters of the ship design and the core content of each specification are extracted.Organize it into important points as the basis and direction of program development.(2)In-depth study of the NAPA program is carried out,detailing the contents of each subsystem,illustrate basic operational commands and logic.Focusing on the NAPA macro program and the operating principle of the Manager,the meaning of each subsystem and option in the Manager one by one is explained.(3)Using a certain type of bulk carrier as the research object,the Manager program is developed,including the procedures used in various aspects of the check.Detailed explanations of the Manager frame editing,variable setting,development of macro programs in each subroutine,etc.Calculate the hydrostatic and tank capacity data,complete stability and damage stability check,freeboard and total longitudinal strength of the current design ship,and display the actual output.Some designs could be compared at the same time during the primary stage and provide theoretical support for design optimization.(4)Summarize the entire development process,based on the completed procedure.Based on the research results of this paper,the future expansion direction of the program is proposed for different ship types and special needs,and the basic ideas are given.