Making Ship Production More Profitable
An important trend in increasing shipbuilding productivity is integrating the computer-aided ship design process. The ship design process is increasingly being performed with the help of computer programs, either individual programs that address single aspects of the design or integrated programs comprised of modules that address a range of ship design aspects.
In the case of integrated com- process is enhanced through individual program modules sharing their results with each other, preferably from a common database.
Modern integrated ship design programs not only improve the efficiency of ship design, they also improve the efficiency and ease of ship production, from lofting and numerical cutting to providing workshop drawings and production information. ADVANCING THE PROCESS The integrated ship design program is a compelling concept, and one whose time has come.
It aims to digitize the traditional ship design 2-D drawing, bills of materials and schedules, and carry out complex calculations, as well as, perhaps most importantly, advance the ship design process into the multiuser environment, and provide the designer and the production shipyard with a full-ship, 3-D database.
The advantages of such a system are numerous, and include: decreased design hours; reduced lead rmeow Hull MoSajSr time; increased productivity; reduction of information errors; and the availability of production-oriented data.
Although many U.S. shipbuilders have invested millions of dollars in CAD/CAM systems, few have reached the ultimate goal, which is total integration of all processes, from early design through production. For example, a yard may have one CAD system for structural design and another for outfitting design. Integration of a ship design program may be viewed from two levels: • Integration among the modules of a ship design program is the most basic level of integration. This level of integration means that the various modules of a program are designed to communicate and share data with one another to at least some extent. This level of integration is characterized by some as an interfaced system rather than an integrated system.
• The more advanced level of integration is by means of a product model, which is a detailed, 3-D description of the ship and its major systems. The product model is a common database that is shared by all the modules.
ENHANCING SHIP PRODUCTION A powerful potential advantaj of integrated ship design progran is that the data generated durir. the design process can be tailored i format and content so that it ca help support the ship productio process.
Virtually all of the programs r< viewed for the purpose of this articl provide at least some input to th ship production process, and se\ eral programs provide significan input.
The following paragraphs de scribe eight examples of integratei design programs. Space constraint and program complexity prohibit < full listing of all features.
For additional information on i particular program and which inte gration level it fits under, see pro gram and company information or page 69.
HULLTECH uses interactive facilities and computer graphics tc provide shell plate surface curves, and a breakdown into individual plates for their development, complete with all marked-on lines (2- dimensional definition, green, minimum rectangle, sight line templates and pin-jig bed). HULLTECH also provides relevant production information for ship floor personnel and HICADEC places great emphasis on supporting the ship production process, with information provided to name, describe and specify exact cutting and assembly operations to the level of individual parts.
Odense Steel Shipyard has used HICADEC on several recent commercial new construction projects.
On these projects the system automated the production of steel detail and outfitting fabrication and assembly drawings; automated the detail planning and budgeting for steel work; and automated material takeoff and requisitioning. It also created a structural database from which the automated welding programs for a series of very large crude carriers (VLCCs) (prepared by one person) which resulted in the automated welding of 100 percent of the midbody sections by Odense welding robots.
IMSA's modules ShipCAM and NC-PyrosLofting address development of the table of offsets through all stages of fairing and lofting to the NC code for computerized plate burning. The program is interactive, and all surfaces can be expanded to flat plate with all markings for frames, stringers, bulbs or thrusters.
TRIBON provides tools to plan the assembly stage of production for hull and outfit items. The TRIBON structural system handles comprehensive bracket generation, nesting of plate parts, workshop drawings and production information, parts and profile lists, templates for bending plates and stiffeners and assembly jig data. TRIBON's outfitting system covers standard material and specification libraries, schematic diagrams, equipment definition and location, modeling of pipes, cable ways and ventilation ducts, isometric drawings, material lists for prefabrication and assembly, weld records, NC bending data, interference control, weight and center of gravity calculations and composite drawings. The electrical modules cover the areas of cable specification and registration, equipment definition and location, cableway registration, automatic routing of cables and installation instructions and feedback.
This article was excerpted from a presentation given by Jonathan M. Ross of Ross-McNatt Naval Architects, at the recent National Shipbuilding Research Program (NSRP) 1993 Ship Production Symposium, sponsored by the Hampton Road Section of the Society of Naval Architects and Marine Engineers.