INTRODUCTION

Design & construction of Naval warships is a complex process. Detailed design needs to incorporate a large set of functionalities for the Float, Move & Fight systems of the warship. The ship’s hull structure consists of shell, decks & bulkheads, which form compartments. Each compartment contains a set of equipment catering to specific functionality required by the ship. Detailed design involves designing a complex network of equipment, cables, pipes & ventilation trunks. Due to the confined & limited space availability, detailed designers face significant challenges in positioning & aligning of the equipment & outfitting elements, while ensuring functionality.

WHAT IS LINE OUT INSPECTION?

Traditional ship construction process involved the following main stages:

  1. Preparation of 3D CAD Model – This is a highly coordinated process involving multiple stakeholders to minimize rework during production. The design team uses specialized 3D CAD software like AVEVA Marine and CATIA.
  2. Generation of Production Drawings – Multiple 2D layout drawings of each compartment are generated at a reduced scale, say 1:20, and sent to the production floor.
  3. Line-out inspections (LOI) – Before installation of components, the production agency interprets the drawings and physically marks each outfitting component on the six faces of the compartment in 1:1 scale. The owner’s rep, along with the design & production teams, conducts joint inspections of each compartment to ensure compliance to design requirements, with special focus on two requirements:
    • Feasibility of fitment without interferences
    • Ergonomics and maintainability of the compartment
  4. Fitment & installation of equipment – The equipment & systems are installed only after the line out inspections and associated approvals from the owner’s rep.

CHALLENGES WITH LOI

LOI is a painfully time consuming process that requires multiple iterations. It very often hinders the ship construction process from moving ahead. The key challenges include:

  1. Substantial delay due to slow & manual workflow – On an average, the LOI for 7 to 10 compartments could be completed in a month considering 2 revisions for each compartment. For a ship with 395 compartments, this would require over 3.5 years just for the LOI!
  2. Huge cost & time incurred due to need for full scale physical mockups/models for visualization of certain critical compartments like engine room, bridge & operations rooms.
  3. Extensive rework & changes during actual production stage due to poor appreciation of interferences, maintenance envelopes & movement within & between compartments.
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THE PROMISE OF VR TECHNOLOGY

The capability of Virtual Reality technology to transform the current LOI workflow to a digital approach would allow the following:

  • 1:1 scale visualization of the ship’s 3D model, removing the need for physical mockups & inspections, by giving an accurate representation of model dimensions
  • Digital tools for accurate measurements & validations of design requirements like headspace, equipment movement & accessibility, while providing improved user experience
  • Rapid iterations to the design can be made to incorporate user feedback without incurring huge time & costs

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DIGITAL TRANSFORMATION REQUIREMENTS & CHALLENGES

Despite the promise of VR to enable digital transformation of the LOI process, the implementation ran into the following challenges:

  1. Integration with 3D CAD models – CAD software use proprietary formats to store geometry and other data. Conversions from CAD to other formats is a manual, slow and error prone process. Furthermore, due to the complexity of ship designs, the CAD data is fairly large in size. Software should be able to load, display & provide interactive walkthrough of the data.
  2. Soft changes, feedback & validation tools – The software needs to enable user comments made during reviews, update the model as per changes to the design and provide validation tools like picking & movement of equipment for collision checks of outfitting elements.
  3. Digital Human models – The software needs to incorporate digital human models for performing ergonomics & human factored engineering. Actions of the user & operator should be tracked and replicated in the virtual compartment to mimic physical inspection & validation workflow. Any interference with machinery and objects should be highlighted.

SOLUTION & RESULTS

Exxar solution along with Stream, Build & Human modules allowed meeting all user requirements. Stream allowed integrating with a wide variety of 3D CAD software using its unique 3D plugin approach. Digital measurement, model movement & annotation tools enabled model validations while ensuring that all user comments were stored digitally for subsequent reviews. Through suitable integration with a full-body suit, digital mannequins are added to the virtual compartment, allowing user to interact naturally and validate ergonomic aspects.


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The following results were achieved by the Shipyard as part of this digital transformation exercise:

  1. Duration of inspections was reduced by over 2 years, by eliminating the physical LOI process. The digital workflow allowed an average of 22 compartments to be approved within a month, reducing the inspection time to under 18 months!
  2. Direct savings of over $3 Million attributed to the costs of physical markings, prints, revisions & other LOI logistics.
  3. Rework was reduced substantially with better appreciation of layouts, maintenance envelopes & interferences. Rework / modification at later stages of ship construction entail cutting / welding of the ship structure which reduces the life of the ship in addition to consequential delays. Along with reducing the cost of the ship, reduction in the life of the ships is also avoided ensuring greater customer satisfaction.
  4. Improved ergonomics & habitability – Compartments were modeled as zones between two structural bulkheads. All compartments in a zone were inspected simultaneously, enabling better appreciation of ergonomics, passing through systems, local and global effects of ship systems & equipment.
Praveen Bhaniramka

3D & Immersive Visualization industry veteran, Author of multiple IEEE research papers, Technology consultant, Trainer & Speaker

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