APPROVED redraws requirements for class verification
The Naval Architect: May 2019
The humble 2D drawing, once the simplest and most effective means of defining the product, has become increasingly superfluous.
Except, that is, in one key regard. Surprisingly perhaps, 2D technical drawings remain an explicit requirement when naval architects and shipyards submit their hull designs to classification societies, to ensure they fulfill both Class and Statutory requirements. The lack of compatibility between different software systems, not to mention the rapidity with which hardware, software and file formats can become obsolete, complicates the long-term accessibility and maintenance of those records.
Therefore, 2D drawings have remained the safest form of design documentation, with the class society then building its own digital verification model based upon them. Yet to all intents these drawings serve no purpose beyond classification. This process is enormously time consuming on both sides, given that with every design revision the society may need to re-verify.
Over the past 20 years there have been a number of unsuccessful attempts by the maritime industry to arrive at an open standard that would facilitate the data exchange of 3D ship models for class approval. One of the primary obstacles was that the different software vendors, understandably, were historically reluctant to cede any competitive advantage to their rivals.
Yet there is a growing realisation that standardisation is a prerequisite to digitalisation and allowing machines to speak to each other, something now being felt acutely in the development of other areas such as e-navigation and autonomous shipping.
Conscious of this rapid evolution, three years ago DNV GL decided it was time for another attempt at finding a solution with a new joint industry project: APPRoval of Engineering Design models (APPROVED). The project brings together expertise from CAD/CAM software providers Aveva, Hexagon (formerly Intergraph) and Siemens; along with ship designers and builders Rolls-Royce Marine, Ulstein and Chantiers de l’Atlantique; as well as 3D and PLM implementation specialists Digitread.
The result of their combined efforts is the development of an interoperability specification that the partners hope will allow for shipbuilders and class societies to engage in complete sharing of the digital workflow using a common specification for 3D models.
“It’s really a collaborative effort from the industry,” explains Ole Christian Astrup, senior principal researcher, maritime transport, at DNV GL, who acts as the project manager. “When we started we didn’t know whether it would be a success but are now attracting a lot of interest.”
The key objective of the APPROVED project has been the development of a Digital Exchange Specification (DEX), or data schema, agreed upon by the project partners: the Open Class 3D Model exchange (OCX). Uniquely, OCX is said to specifically address the needs of the classification society and shipbuilders for fully digital information exchange.
Effectively, OCX acts as a conduit between the design tools and class confirmation tools, highlighting the structural information the class society requires and formatting it in a way that can be easily processed.
Astrup explains: “3D CAD systems have evolved tremendously over the last decade, and the vendors have put enormous effort into their performance and complexity. Technology wise the three software vendors who worked in the partnership – Aveva, Siemens and Intergraph – each have all the information that we need and have been able to resolve all our design requirements.”
A number of pilot projects testing the process on real designs are already underway, with rollout of OCX as the basis for a DNV GL service expected to take place sometime in 2020. Yet while DNV GL has been the facilitator of the project, Astrup is keen to emphasise that its success is entirely down to the collaboration between the project partners and their various areas of expertise. “The vendors have the competence to support it from a technology base, but the designer and builder know how it can benefit their process.”