Trans RINA, Vol 156, Part C1, Intl J Marine Design, Jan –Dec 2014
meet the market demands for the market to be economically versatile.
3.1(g) Modularity
The owner needs to consider modularity of the vessel interior as is now the trend with Literal ships such as the General dynamics concept or the single warfare operating platform (SWAP) which allow modules and interiors to be reconfigured for its intended use. This level of modularity is not new and has been in practice by the airline industry for many years. For example, planes can be converted from passenger to cargo or even transporting Olympic show jumpers in the matter of a day. As vessel sizes and vessel costs increase for round three the level of modularity needs to be considered at design stage. The other consideration for modular interiors is that once the infrastructure has been laid down then fitting out is very fast as will be explained in the following section.
3.2. CONCLUSION
The latter section has detailed the rigor that needs to be undertaken to ensure that the Vessel design becomes a viable financial proposition. The formalized methodology of gaining the specification and future state not only gives
a solid foundation for the design
process but also a sound business plan for banks or investors who would want to secure their investment over the period of the finance. As such this degree of detail should be used when trying to raise finance and spread risk in the business plan. When considering the fleet strategy the consideration should be made that a company with 1 vessel is more likely to fail than a company with larger number of vessels thus reducing the risk.
4. HOW TO REDUCE BUILD TIME AND COST
Once a robust specification process undertaken this needs to be translated
has been into digital
designs and a manufacturing system. This section will detail how to design modularity into the digital design, the creation of sub systems and the creation of a modular infrastructure and platform and reduction in production costs. However; it
is important that the
design for manufacture and assembly axioms are understood to put into context the following sections. The axioms are; [5, 6, 10 & 18]
Minimize the number of parts Minimize the number of part variations Use modular design Use multi-functional parts Design for top down assembly Maximize part mating or compliance Minimize part handling and presentation Avoid flexible parts
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Design parts to self-fixture Maximize visibility of assembled area Avoid hazardous material or processes
4.1 PARALLEL/ CONCURRENT PROCESSING AND PLANNING.
The traditional method for small vessel construction has been a linear process (fig 4.1a) whereby one discrete
process is followed by another discrete
process. For example; it would be expected that the electricians would lay the services followed by the carpenters etc. In reality this never happens and it is not unusual to revisit parts of the fit out with removal and secondary or even tertiary works.
Such work and
rework and its associated delays are attributable to poor specification, design and planning. More significantly, the linear process flow ties up a great deal of cost, WIP and working capital employed, in terms of the most expensive part of the build which is the hull and the machinery. In the perfect world the highest capital cost units would be fitted last to reduce the strain on cash flow and the stage payments, yet this is not possible with building boats.
Modern design for manufacture methods prescribe
that not only the direct cost of build is reduced but also the amount of time that working capital is tied up and is normally measured by a metric called stock turns. As such the objective is to ensure that the highest capital cost aspects of the product are fitted as late as possible and as close to final invoice or stage payment date.
For vessel build large or small, reduced lead time and cost reduction can be achieved by a process flow called parallel processing or concurrent engineering (figure 4.1b).
4.1(a) Digital technology
The distinct difference with this process flow is that of the use of CAD at the design stage to define as much of the fit out as possible. Most supplier of OE equipment now have their equipment in CAD model forms so these can be placed within the overall design model with a great degree of accuracy. With modern CAD systems such as Solid Works the amount
of
information rendered to the designer , includes weights , tolerance clashes, FEA stress analysis, flow dynamics, air movement and for interior design and ergonomics virtual reality is now common. Further important developments also include assembly simulation and bill of material control, giving full financial control. Every change made during the design stage automatically updates the BOM and the cost model so the project team know the project costs down the nearest washer. This aspect will be covered in more detail later in this paper due to its importance [11, 12, 8, 14, 15 & 28].
©2014: The Royal Institution of Naval Architects
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