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Levels of Modularity


Modularity in construction of warships could
be realised at different levels and stages of construction starting from design
stage. Modules can be as small as a single piece of equipment mounted on their
common supports and ready for installation on panel, on-block or on-board or a
complex assembly of equipment, piping, floors, electrical and other systems,
all pre-mounted on a support structure1. The different levels of
modularity applicable to warship construction are enumerated in succeeding

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Modularity. Modular design is a precursor to modular
construction process and helps to integrate the Engineering Hub and the
Manufacturing Hub. This forms part of the PLMS. The degree of modularity to be
achieved in a project is decided at design stage and an increased degree of modularity
would enable sub dividing the design task,
help undertake simultaneous work on different sub-systems and
a shorter development process. When the ship is designed and divided into
blocks and mega blocks, functionality should be kept the same in the module from one design to the next,
and movement of functionality between modules should be minimised. Functionally
related equipment, systems, storage tanks etc. are identified and located to
reduce the distributed system footage and maximize unitisation and
standardisation potential2. Interfaces between
systems are so designed that they are
simple, stable, robust and standard. The goal is to identify the largest
possible assembly of the equipment and outfitting components that can be
completed in the workshop, assembled concurrently with hull construction and
easily lifted without exceeding the available crane-lifting capacities and
workload during the installation3. The final module content
and layout is confirmed by a series of studies, build strategy, and preliminary
system routeing. Thus, modules are optimised, based upon engineering, spatial,
regulatory and economic parameters.


In modular design, the required redundancies
and system fail safe levels need to be decided very early as re-engineering to
meet late stage demands is wasteful. The productivity heavily depends on the
design philosophy and is also closely related to the size, the independence and
integrity of each module achieved prior to its assembly to create the platform.
The design stage incudes basic design, 3D modelling and virtual reality and
design & engineering in modules. The planning and design of modules require
detailed information regarding equipment dimensions, weights, interfaces and
constraints which are provided by the suppliers. The suppliers are therefore
required to be identified early and the process is easier in case of warships
as most of the suppliers are based on the approved equipment vendors by IN.


Standardisation.     During design process, it is essential to
create standardised building blocks that are defined at their interfaces. Modularity
at the design level aims at meeting all prescribed technical specification of
the Customer. This primarily addresses the functional partition as well as
geographical partitions and also has a direct impact on the displacement of the
vessel. For a warship, the segregation of functions are reflected in formation
of blocks mostly for control rooms, accommodation spaces, machinery compartments,
weapons compartment, super structure etc. 
Standardization is a prerequisite for successfully designing and
building modules4.
With the help of standardization, the number of unique guidelines, procedures,
processes, drawings, documentation, physical parts, components, equipment and
systems necessary to manufacture a ship is minimized. The principal objective
is to minimize design, production, life cycle and acquisition costs.



Figure 1. Construction

Modularity in
Construction.         This
stage is progressed based on the modular design mentioned above. The blocks, major
assemblies and sub-assemblies are fabricated and tested separately. Mega blocks
are made by joining smaller blocks. Modularity at the construction level
envisages construction of blocks











or mega blocks in different location /
shipyards; and final integration at the prime contractor’s shipyard. At the manufacturing
stage, pre-outfitting is done on the decks. Such pre-outfittings in dedicated
workshops with system / sub-system checks ease out the integration process to a
large extent. ‘Full Kit Management System’ principle need to be applied, which
demands seamless coordination between manufacturing and procurement processes
to synchronize the equipment deliveries in sync with manufacturing process5. This concept of
modularity forms the back-bone of modern shipbuilding and results in reduction
of risks due to re-work and consequently increased productivity leading to
optimization of time and reduction of cost.


Modules. Module is a structurally independent
building block of a larger system with well-defined interfaces6. Modularisation allows breaking
the complex structures into self-sustainable blocks / modules. By this, the
engineer will be able to manage complex systems in a structured way. Modules
can range from equipment modules, hull assembly blocks, outfitted hull blocks
to outfitted panel assemblies. Ship modules are formed by assembling sections
consisting of smaller subassemblies such as piping sections, ventilation
ducting, other shipboard hardware and major machinery items with other
shipboard sensors and weapons.  Modules
which are 60 % to 90 % complete are then moved to the final consolidation site
where they are aligned and then welded together on land to form the completed
ship hull. This process is called integration of modules. The various building
blocks or modules could be subcontracted either to other shipyards or to steel
fabricators who are not necessarily shipyards.

2. Ship Modules



Outfitting.             In modular approach of outfitting, the
modules can be manufactured and assembled by smaller, more flexible
manufacturers located outside of the shipyard. Such alternative manufacturers
can be significantly more efficient than the traditional fully-integrated
shipyard that often struggles to maintain high levels of efficiency for the
many different worker trades and facilities needed to build a ship7. The long term statistics
in shipyards indicate that the cost of work performed in the workshop compared
with the same work performed on section, on-board or in final outfitting is
related as 1: 3: 5: 7. It states that the job with x working hours,
which is relocated from section to workshop, is x/3 cheaper, also
shifting job from on-board to workshop is x/5 cheaper, and shifting a job
from final outfitting to workshop consists of x/7 of preceding working
hours8. Some potential benefits
that could be enabled by modular outfitting are as follows9:-


(a)       Improving
productivity and efficiency within the production labour force.


(b)       Reducing
outfitting costs and man hours.


Modules built outside the shipyard can lead
to improved quality and further reduction in costs.


Standardised modules can lead to lower costs
through reduction in design, reduction in material procurement and reduction in
production time.


the modular outfitting approach has some disadvantages, indicated as follows:-


(a)       It
reduces design freedom, due to the obstacle of installing functional systems in
limited space.

(b)       Modules
may get heavier due to stronger supports and foundations.


(c)       Need
for experienced designers who can link conceptual and production design with
the capabilities of shipyard outfitting technology.


Equipment Level Modularity.      Development of compact and easy to install ship borne equipment is
the trend world over, but more important is to ensure the modularity of
equipment with complete associative systems10. The
complete assembly of equipment or group of equipment is mounted on specially
configured skids outside, prior lowering into the ships. This would help to
reduce the number of pipe spools required and enhance prefabrication and
parallel assembly of components. In the maintenance and refit point of view,
for undertaking routines and replacement of parts and assemblies, they would have
easy pull out and jack up facilities for extremely quick replacement, thus
avoiding a lot of degutting.


Compartment Level Modularity. Standardisation of compartments’ designs could be used for ships of same as well as
different classes11. This would
avoid re-engineering, every time a new ship design is processed. Modularity of
compartments offers assembling the complete compartment outside at the most
conducive location and assembled at the ship assembly site. Decks such as
flight decks, hangar, accommodations, E/Rs with propulsion systems etc. would
be identified as potentials for modules. The accommodation spaces would be
fitted with modular bathrooms and toilets which are manufactured as a module
and connected up with piping and associated electrical connections. Electronic
Modular Enclosures (EMEs) are structures that can be used to enable use of COTS
equipment in naval environment by isolating the COTS equipment from shocks, EMI
and provides quality power12. EMEs
helps to achieve the mil standards for COTS equipment. The 3D
view of each compartment as brought out before could be generated to simulate
walk through of fully populated compartments and ship with each item placed at
its specified locations. Such virtual models are of immense help in
visualizing, analysing and resolving various potential problems like
accessibility, operability, maintainability interference, rework etc., thereby
improving the production efficiency many folds13.


Figure 3. 3D virtual
ship compartment walkthroughs



Platform Level Modularity.           Multi-mission
and multi-role capability is the requirement of a modern day warship as it
operates in a multi-threat 3D environment. Modularity in platform level could
help meet the threats arising from subsurface, surface, air and space through
design and construction of similar class of ships with different mission
requirements. Some sections of the ship can be designed as the base ship and
mission specific modules can be added as required to produce specific solution.
Containerization of role packages has been developed, where containers can be
lowered into the ship for specific missions. The interfacing requirements are
worked out and cables are plugged in / out during role reversal. These
containers could be plugged into different class of ships also. Such “Plug and Play”
concepts are playing a pivotal role in bringing together flexibility to achieve
mission modularity14.



Types of Modularity


Component Sharing Modularity. Use of same component across
multiple products to provide economies of scale is called component sharing
modularity. This type of modularity reduces cost while allowing variety and
faster end-product development15.


Component Swapping Modularity. This refers to the use of
two or more alternative component types being used in the same basic end
product creating different product variants belonging to the same product
family. An example would be different radar systems used for the same frigate


Bus Modularity.      Use
of standard
interface systems allows different components to be assembled quickly. Bus
modularity can be applied for equipment and systems including weapon, radar and
communication systems.









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