The main task of the PRETTI-2 Working Group is the restructuring of the 3D diffraction program PRECAL and the time domain ship motions program PRETTI-2. The present codes have their origin in the early 90’s and have since then been modified and extended many times. The introduction of the concept of generalized modes – which capture both the rigid body modes and the flexural body modes – made it necessary to redesign and rebuild the program codes from scratch. The PRETTI-2 WG aims at the use modern software standards for the definition of requirements and specifications, code style and documentation (user, theory and software manuals).