Warship Design : A Complex Process
When we talk of the design of any warship, we very quickly jump into what missiles it carries be ASuW, ASW, SAM etc, what heli it carries and the most looked at by defence enthusiasts generally is the appearance – if the design looks very modern. While this is very important, it should also be noted that looks are of no use if they do not give any functional advantage for the design in question amongst its rivals. Warship design is not a smooth straight line process. It is an iterative one comprising of many intelligent guesses based on experience with previous design that hugely supplements the core research that is being carried out. Such designs are called type ships. They serve the purpose of confirming that the initial design arrived at is nearly in-line with the objectives intended for. This serves as a baseline over which refinements are done to arrive at the principal dimensions. The type ship also serves the purpose to try out different ratios of dimensions that define the ship form and ultimately the performance.
From these principal dimensions, initial assessment of the draught, stability and power requirement can be made, which of course needs to be improvised iteratively. It is often referred to as a spiral process. But do note that, in the event of a major change happening due to some standard or regulation change, the design progress would have to fallback in order to align with the new standards or regulations, which can delay the project to some extent. Not all factors are considered initially in the design stage. The major ones considered are initial stability, large angle stability following which the ship is designed for resistance optimization. Once the form is finalized, the internal layout is decided based on experience and the requirements. Following which damage stability is checked for. Later on, the assessment of longitudinal bending moment and hydro-elastic analysis is done that helps in deciding the required frame spacing to meet the strength requirements.
Nowadays with optimization softwares available, the design process time is reduced considerably. Let us now take a look at the components of the design process.
The Design Process
Enlisting the components as below:
- Feasibility Studies
- Contract Design
- Full Design
Let us now take a look at these components of design process to get the long term agenda of design.
Feasibility studies are carried out to confirm if an existing design can meet the requirements with existing technology and if not, what improvements are possible within the budget and the time available in order to get the contract. Several design options are compared with respect to trade-offs in case of conflicting requirements. And these designs are what we usually see at the defence expos.
As the name suggests, contract design is the design that is agreed by the designing party and the Navy. And this design would feature all the detailing, the layout spaces and again model testing carried out to confirm the performance characteristics that were arrived at in the initial design stage.
The full design is where the actual production stage drawings are made and once the warship is manufactured, sea trials are done to establish that the contract has been met. Various tests with regard to watertight integrity, structural integrity, piping systems, electrical systems and integration of various on-demand systems are carried out. This will also be followed by extensive trials on ship performance and weapons testing in the sea-states that the warship is designed to operate in. And finally the associated documentations like the stability book, handbooks for operators and the maintainers are prepared in detail.
Use of dependency diagrams
A dependency diagram is provided by the designer to show the interaction of various elements that lends it a specific capability. This will show how failure of one element will affect the overall performance of that particular system. These are usually expressed in the form of probabilities of failure of the individual component and the system as a whole. Recently use of neural networks in the prediction of failure is very much rising and this coupled with advanced data visualization techniques has been very helpful.
Having discussed about the warship design in a crisp manner covering the long term agenda, in the next article we shall take a step ahead with regard to what any ship is primarily and most importantly required to do, without which it is useless and this is simply put – “to float”. In the next series of articles which shall be specified in parts, we shall discuss about the terminologies in naval architecture, floatation of ship and its stability in static conditions. That being said, we shall now be moving on to purely technical side from the general ones we discussed here.
Coming up next: Ship Terminologies