Computer aided design and production assignment based on Brief History of CAD in shipbuilding and Application of CAD in shipconstruction.

1. Computer Aided Design & Production
Assignment 1
Chinmay Korgaonkar
B.tech NA&OE 3rd
Year
1804609038
Brief history of CAD/CAM
Computer Aided Design software development dates back during the Cold war period but
CAD/CAM systems were not commercially available until 1957s. The beginnings of CAD can be
traced to the year 1957, when Dr.Patrick J.Hanratty developed PRONTO the first commercial
numerical-control programming system. In 1963 CAD took an enormous step forward with the
introduction of SKETCHPAD in 1963 by Ivan Sutherland which demonstrated the basic principles
and feasibility of computer technical drawing. The first commercial applications of CAD were in
large companies within the automotive and aerospace industries, as well as in electronics. In early
1960s during the industrial development period General Motors developed DAC (Design
Augmented by Computer). In 1971 by Patrick J. Hanratty supplied code to companies such as
McDonnell Douglas (Unigraphics), Computervision (CADDS), Calma, Gerber, Autotrol, and
Control Data.
In 1981, the key products were the solid modeling packages—Romulus (ShapeData) and Uni-Solid
(Unigraphics) based on PADL- 2 and the surface modeler CATIA (Dassault Systemes). Autodesk
was founded in 1982 by John Walker, which led to the two-dimensional system AutoCAD. The next
milestone was the release of Pro/ENGINEER in 1987, which heralded greater usage of feature
based modeling methods and parametric linking of the parameters of features; this marked the
introduction of parametric modeling.
Also important to the development of CAD was the development in the late 1980s and early 1990s
of B-rep solid modeling kernels (engines for manipulating geometrically and topologically
consistent 3D objects), Parasolid (ShapeData), and ACIS (Spatial Technology Inc.). These
developments were inspired by the work of Ian Braid. This subsequently led to the release of mid-
range packages such as SolidWorks and TriSpective (later known as IRONCAD) in 1995, Solid
Edge (then Intergraph) in 1996, and Autodesk Inventor in 1999.
CAD in shipbuilding industry
Throughout the first half of the 20th century, ships were getting bigger; so it was necessary to work
on larger scales. The templates allowed working on different scales, such as widely used 1:10 scale.
But with growing ship size, the moment came it was no longer practical to use templates. This
happened at a time when the first computers came to shipbuilding industry, promoting the
development of ship design CAD systems. In 1964, as a tool to help SENER born as a marine
engineering company - develop their marine projects. In 1965, the first version of the software was
launched for internal use only under the name FORAN. In 1980 Autoship Systems began building a
reputation for excellence in software development with a rather revolutionary idea - an integrated
suite of PC-based marine CAD/CAM software and services. In 1995 Tribon system was developed

2. which is a group of software’s ( Schiffko, Steerbear, Autokon) Tribon was later acquired by AVIVA
marine in 2004. The year 1995 also led to the formation of NUPAS CADMATIC which is a leading
developer of digital and intelligent 3D-based design, engineering and information management
software solutions for the marine industry, which is used for all kinds of ship, offshore, process
plant, and building constructions etc. Shipconstructor was founded in 1990 which is one of the
leading CAD/CAM software in shipbuilding industry.
Traditionally, most shipbuilding CAD systems focused on hull form definition, naval architecture
calculations and structural design. This changed when new challenges in shipbuilding, demanding
closer coordination between hull structure and outfitting, obliged marine suppliers to devote special
attention to this matter.
Some marine CAD systems (as FORAN) started the development of particular outfitting tools,
others limited tried to find a closer integration with existing plant design oriented systems. The
development of a particular outfitting design tool in FORAN was based on the fact that the actual
requirements for outfitting design are not limited to a close integration with the structural design.
Problems to be solved, regulations, working procedures, nomenclature, production information, etc.
are so particular to ship design that it is convenient to have a dedicated tool rather than try to adapt
an existing one. As time went by, outfitting tools have been increasing the scope of support. Today,
tools usually include particular environments for equipment modelling and layout, piping and
HVAC ducts routing, definition of auxiliary structures (foundations, gratings, ladders etc), and
definition of distributor supports and hangers. In some cases also electrical and accommodation
aspects are considered. Particularities of outfitting design require to work in a pure 3D environment
and with a friendly and suitable user interface.
CAD is mainly used for detailed engineering of 3D models or 2D drawings of physical components,
but it is also used throughout the engineering process from conceptual design and layout of
products, through strength and dynamic analysis of assemblies to definition of manufacturing
methods of components. CAD applications now offer advanced rendering and animation
capabilities so engineers can better visualize their product designs. CAD software like NAPA can be
used to for hull-form modeling and optimization, structural design, Stability and Hydrodynamics of
the hull-form.
Application of CAD/CAM in shipconstruction
Software systems for large shipbuilders is based on the concept of the ‘Ship Product Model’ in
which the geometry and the attributes of all elements of the ship derived from the contract design
and classification society structural requirements are stored. At the heart of the ‘Ship Product
Model’ is the conceptual creation of the hull form and its subsequent fairing for production purposes
which is accomplished without committing any plan to paper. This faired hull form is generally held
in the computer system as a ‘wire model’ which typically defines the moulded lines of all structural
items so that any structural section of the ship can be generated automatically from the ‘wire
model’. The model can be worked on interactively with other stored shipyard standards and
practices to produce detailed arrangement and working drawings. The precision of the structural
drawings generated enables them to be used with greater confidence than was possible with manual
drawings and the materials requisitioning information can be stored on the computer to be
interfaced with the shipyards commercial systems for purchasing and material control. Sub-
assembly, assembly and block drawings can be created in 2-dimensional and 3-dimensional form
and a library of standard production sequences and production facilities can be called up so that the

3. draughtsman can ensure that the structural design uses the shipyards resources efficiently and
follows established and cost effective practices.
Weld lengths and types, steel weights and detailed parts lists can be processed from the information
on the drawing and passed to the production control systems. A 3-dimensional steel assembly can
be rotated by the draughtsman on screen to assess the best orientation for maximum down hand
welding. The use of 3-dimensional drawings is particularly valuable in the area of outfit drawings
where items like pipework and ventilation/air-conditioning trunking can be ‘sighted’ in the 3-
dimensional mode and more accurately measured before being created in the 2-dimensional
drawing.
Stored information can be accessed so that lofting functions such as preparing information for
bending frames and longitudinals, developing shell plates, and providing shell frame sets and rolling
lines or heat line bending information for plates can be done via the interactive visual display unit.
For a numerically controlled profiling machine the piece parts to be cut can be ‘nested’, i.e. fitted
into the most economic plate which can be handled by the machine with minimum wastage This can
be done at the drawing stage when individual piece parts are abstracted for steel requisitioning and
stored later being brought back to the screen for interactive nesting. The order in which parts are to
be marked and cut can be defined by drawing the tool head around the parts on the graphics screen.
When the burning instructions are complete the cutting sequence may be replayed and checked for
errors. Instructions for cutting flame planed plates and subsequently joining them into panel
assemblies and pin heights of jigs for setting up curved shell plates for welding framing and other
members to them at the assembly stage can also be determined by using CAD.