Lesson Twenty-four Application of Engineering Economics to Ship design The general approach Earlier Parts have given a broad picture of the economic environment within which marine transport operates, and the mechanics of making economic calculations. Ship design links the two i.e., the marine transport requirements must be developed into a series of feasible ship designs, which must then be evaluated for their technical and economic performance, covering the following Trading pattern and operating environment Range of feasible technical designs Estimation of building and operating costs, and income Economic evaluation of alternatives Although a superficial glance might suggest that such a process is a matter only for shipowners, his is not so, the shipbuilder is also concerned, in two principal ways Specialist knowledge To design the optimal ship, extensive experience is required of the influence of different, design features on first cost. The builder is much better able than the shipowner to quantify accurately the cost of alternative hull proportions, materials, machinery arrangements, etc Commercial competition As shipowners have become more ready to apply the principle of income and costs, rather than minimising ship first cost, there has arisen a greater need for shipbuilder to show not that his design is necessarily the cheapest, but that it is the most profitable This approach has been used by the aircraft industry for some time, and is particularly applicable to standard ship designs Traditionally, ship design from the builder s viewpoint has meant the receipt of an enquiry from a shipowner, accompanied either by a statement of requirements or an outline design. In the former case, a design is worked up, often using a basis ship; in the latter, the design is checked out. Time usually prevents anything but a single design being investigated then the cost is estimated and a price submitted to the shipowner. If the tender is successful, a contract is placed, and the design worked up into a complete building design. There are thus two principal stages of design (i) Preliminary or tender design (ii) Detailed or contract design Stage (ii) will not be considered here, because the principal features have already been settled and calculations are largely in the form of analytical procedures and detailing for production The importance of stages(i) is often overlooked. U. K. shipbuilders receive over 1000 enquiries for ships in a typical year, resulting in a very large number of outline designs, but less than 10% result in orders. Thus, tender designs outnumber contract designs by at least 10 to 1. It is at this creative stage that the approation of engineering economics has its greatest pay-off The traditional approach survived during the many years in which developments in ship types were slow, e.g., 1910 to 1960.It has proved inadequate for the highly competitive years since then, during which ship types have changed significantly, because
Lesson Twenty-four Application of Engineering Economics to Ship Design The general approach Earlier Parts have given a broad picture of the economic environment within which marine transport operates, and the mechanics of making economic calculations. Ship design links the two, i.e., the marine transport requirements must be developed into a series of feasible ship designs, which must then be evaluated for their technical and economic performance, covering the following: Trading pattern and operating environment Range of feasible technical designs Estimation of building and operating costs, and income Economic evaluation of alternatives. Although a superficial glance might suggest that such a process is a matter only for shipowners, this is not so, the shipbuilder is also concerned, in two principal ways: Specialist knowledge To design the optimal ship, extensive experience is required of the influence of different, design features on first cost. The builder is much better able than the shipowner to quantify accurately the cost of alternative hull proportions, materials, machinery arrangements, etc. Commercial competition As shipowners have become more ready to apply the principle of income and costs, rather than minimising ship first cost, there has arisen a greater need for a shipbuilder to show not that his design is necessarily the cheapest, but that it is the most profitable . This approach has been used by the aircraft industry for some time, and is particularly applicable to standard ship designs. Traditionally, ship design from the builder’ s viewpoint has meant the receipt of an enquiry from a shipowner, accompanied either by a statement of requirements or an outline design. In the former case, a design is worked up, often using a basis ship; in the latter, the design is checked out. Time usually prevents anything but a single design being investigated .then the cost is estimated and a price submitted to the shipowner. If the tender is successful, a contract is placed, and the design worked up into a complete building design. There are thus two principal stages of design: (i) Preliminary or tender design. (ii) Detailed or contract design. Stage (ii) will not be considered here, because the principal features have already been settled and calculations are largely in the form of analytical procedures and detailing for production .The importance of stages (i) is often overlooked. U.K. shipbuilders receive over 1000 enquiries for ships in a typical year, resulting in a very large number of outline designs, but less than 10% result in orders. Thus, tender designs outnumber contract designs by at least 10 to 1. It is at this creative stage that the approation of engineering economics has its greatest ‘pay-off’. The traditional approach survived during the many years in which developments in ship types were slow, e.g., 1910 to 1960.It has proved inadequate for the highly competitive years since then, during which ship types have changed significantly, because
design was usually based on previous ships, yet there was no existing experience of the new ship types enerally only one design for one size and speed was investigated No economic evaluation were made either for the single design or any alternative Traditional cost estimating methods did not reflect the changing ship types and production method A modern approach aimed at improving designs of ship requires good collaboration between potential owners and builders Shipbrokers can contribute to this dialogue, while it is often desirable for consultants to be used to investigate the range of possibilities(especially for the smaller ship operator on account of their independent commercial status, and the availability of suitable staff. A comprehensive process includes the following (i) Investigation of transport demand and corresponding market research (ii)Concept formulation: range of possible technical solutions, ship types, sizes and speeds (iii) Preliminary technical design of a number of alternative(often using specialised computer programs) (iv) Estimates of first costs, operating costs and income of the alternatives (v) Economic evaluation of the alternatives (vi) Selection of the optimal design, either by judgement, or mathematical programming ith cli (viii) Contract, detailed design and construction of the final selection the practicing ship designer should be interested in every aspect of these stages, but here we are concerned mainly with stages, but here we are concerned mainly with stages(iii), (iv) and (v). The relationship between these activities are shown in design spiral. The important feature of the design spiral concept is that each successive cycle is made with an increasing of possible designs. The spiral known information on cargoes and routes, generating a matrix of several hundred potential designs. Before the economic evaluation is made, each combination of principal particulars has its design features evaluated in terms of capacity, deadweight, trim and stability, and cost After the first cycle, the matrix is reduced in size by the application of technical criteria, e.g. stowage factor too small or insufficient stability, and of economic criteria, e.g., inadequate rate of return. The second cycle focuses on the optimal region and enlarges it, examining a few tens of designs in greater depth, using the results of the first cycle as first approximated The results of the second cycle may be sufficient for giving price indications to a shipowner for a range of possible designs. For a more detailed estimate, a third cycle may be made in still greater depth, but for only a single design or a very small number of designs Such a system is ideal for computers, where each intersection of spoke and spiral can be sub-program, increasing in complexity as each spoken is traversed out steelmasses are initially estimated from principal dimensions and coefficients, and subsequently from actual scantlings. The early cycles treat each function as continuous, as at this stage relative values are more important than absolute values. The later cycles will use the step functions that may apply in practice, e. g, diesel engines available with integer number of cylinders. The application of step functions too early may lead to the
- design was usually based on previous ships, yet there was no existing experience of the new ship types. - Generally only one design for one size and speed was investigated. - No economic evaluation were made either for the single design or any alternative. - Traditional cost estimating methods did not reflect the changing ship types and production methods. A modern approach aimed at improving designs of ship requires good collaboration between potential owners and builders. Shipbrokers can contribute to this dialogue, while it is often desirable for consultants to be used to investigate the range of possibilities (especially for the smaller ship operator) on account of their independent commercial status, and the availability of suitable staff. Acomprehensive process includes the following: (i) Investigation of transport demand and corresponding market research (ii) Concept formulation: range of possible technical solutions, ship types, sizes and speeds (iii) Preliminary technical design of a number of alternative (often using specialised computer programs) (iv) Estimates of first costs, operating costs and income of the alternatives (v) Economic evaluation of the alternatives (vi) Selection of the optimal design , either by judgement, or mathematical programming techniques (vii) Discussion of the proposed design (and any suitable alternatives ) with clients (viii) Contract, detailed design and construction of the final selection. the practicing ship designer should be interested in every aspect of these stages, but here we are concerned mainly with stages, but here we are concerned mainly with stages(iii),(iv) and (v). The relationship between these activities are shown in design spiral. The important feature of the design spiral concept is that each successive cycle is made with an increasing degree of complexity, but a decreasing number of possible designs. The spiral starts with known information on cargoes and routes, generating a matrix of several hundred potential designs. Before the economic evaluation is made, each combination of principal particulars has its design features evaluated in terms of capacity, deadweight, trim and stability, and cost. After the first cycle, the matrix is reduced in size by the application of technical criteria, e.g., stowage factor too small or insufficient stability, and of economic criteria, e.g., inadequate rate of return. The second cycle focuses on the optimal region and enlarges it, examining a few tens of designs in greater depth, using the results of the first cycle as first approximation. The results of the second cycle may be sufficient for giving price indications to a shipowner for a range of possible designs. For a more detailed estimate, a third cycle may be made in still greater depth, but for only a single design or a very small number of designs. Such a system is ideal for computers, where each intersection of spoke and spiral can be sub-program, increasing in complexity as each spoken is traversed outwards, e.g., steelmasses are initially estimated from principal dimensions and coefficients, and subsequently from actual scantlings. The early cycles should treat each function as continuous, as at this stage relative values are more important than absolute values. The later cycles will use the step functions that may apply in practice, e.g., diesel engines available with integer number of cylinders. The application of step functions too early may lead to the
area to be enlarged proving non-optimal when more accurate design information has been generated It should be noted that principal dimensions are the independent variables. Deadweight al though a convenient and simple measure of ship size is a merging of three one-dimensional measures which does not reflect the relative importance of length, breadth and draught(or depth for volume-limited ships). There is an infinite number of ships which can be designed to have equal deadweight, but one of these will prove to be more economical than all the others, given particular operating and financial circumstances. Route characteristics generally have a strong influence on the principal dimensions which, in conjunction with hull fullness, may determine displacement and, for a particular ship type, largely determine ship also. Hence, deadweight tends to be a drop-out from the calculation and should not require to be attained exactly in a broad-based design system. What is required is the optimal ship within a general band of deadweight and speed. Allowing the individual dimensions to take up whatever values produce the most profitable ship within any given constraints, such as availability of cargoes and port facilities Such a design system is most easily applied to the straightforward ship types( such as bulk carriers)which dominate the number of enquiries; in practice, this frees valuable design effort for the more complex ship type From "Engineering Economics and Ship Design"by 1. L Buxton, 1976) Technical Terms 1. engineering economIcs工程经济学 17. pay-off效果 2. marine transport海上运输 18. collaboration合作 3. economic environment经济情况 19. shipbroker船舶经纪人(中间人) 4. feasible technical design可行的技术设20. mathematical programming techniques 数学规划技术 5. building costs建造成本,造价 21. client买主 6. operating costs营运费 22. design spiral设计螺旋线 7. Income收入,收益 23. technical criterion(复数 criteria)技术横 8. economic evaluation经济评价 9. alternative方案 24. economic criterion经济横准 10. commercial competition商业竞争 25. spoke径向辐条线 1l. present worths现在的价值 26.sub- program子程序 12. standard ship标准船 27. step function阶梯函数 13. enquiry探询 28. integer number整数 14. basis ship母型船 29. independent variable独立变量 15. tender投标,供应船 30. broad- based designed system笼统的设 16. contract design合同设计 计系统
area to be enlarged proving non-optimal when more accurate design information has been generated. It should be noted that principal dimensions are the independent variables. Deadweight, although a convenient and simple measure of ship size is a merging of three one-dimensional measures which does not reflect the relative importance of length, breadth and draught (or depth for volume-limited ships). There is an infinite number of ships which can be designed to have equal deadweight, but one of these will prove to be more economical than all the others, given particular operating and financial circumstances. Route characteristics generally have a strong influence on the principal dimensions which, in conjunction with hull fullness, may determine displacement and, for a particular ship type, largely determine lightship also. Hence, deadweight tends to be a drop-out from the calculation and should not require to be attained exactly in a broad-based design system. What is required is the optimal ship within a general band of deadweight and speed. Allowing the individual dimensions to take up whatever values produce the most profitable ship within any given constraints, such as availability of cargoes and port facilities. Such a design system is most easily applied to the straightforward ship types (such as bulk carriers) which dominate the number of enquiries; in practice, this frees valuable design effort for the more complex ship types. (From “Engineering Economics and Ship Design” by 1. L. Buxton, 1976) Technical Terms 1. engineering economics 工程经济学 2. marine transport 海上运输 3. economic environment 经济情况 4. feasible technical design 可行的技术设 计 5. building costs 建造成本，造价 6. operating costs 营运费 7. income 收入，收益 8. economic evaluation 经济评价 9. alternative 方案 10. commercial competition 商业竞争 11. present worths 现在的价值 12. standard ship 标准船 13. enquiry 探询 14. basis ship 母型船 15. tender 投标，供应船 16. contract design 合同设计 17. pay-off 效果 18. collaboration 合作 19. shipbroker 船舶经纪人（中间人） 20. mathematical programming techniques 数学规划技术 21. client 买主 22. design spiral 设计螺旋线 23. technical criterion (复数 criteria) 技术横 准 24. economic criterion 经济横准 25. spoke 径向辐条线 26. sub-program 子程序 27. step function 阶梯函数 28. integer number 整数 29. independent variable 独立变量 30. broad-based designed system 笼统的设 计系统
Additional Terms and Expressions 净现值 16. depreciation折旧费 rate需要的货运费率 17. maintenance and repair cost维修费 3. the time value of money钱的时间价值18. Insurance保险费 4. capital recovery factor资金回收因数19. fuel and lubricating oil costs燃润料费 5. average annual cost平均年度费用 20. stores物料费 6. Interest rate利率 21. port charges港口费 7. annual return年收益 22. cargo handling charges装卸费 8. annual cost of capital recovery年资金回23. administration企业管理费 收额 24. crew expenses船员费 9. present worth factor现值因数 25. freight revenue运费收入 10. tax rate税率 26. complex economic criteria综合经济指 1l. port days per round trip每航次停泊时 单位运输成 戈本 12. round trip per annum年航次数 28. recovered years of investment投资回收 13. handling rate装卸效率 年限 14. vessel investment船舶投资 29. profit per annum年利润 15. total costs总成本 30. life of ship船舶使用年限 Notes to the Text 1. To design the optimal ship, extensive experience is required of the influence of different design features on first cost这个句子中,主语成分被谓语 is required隔离,见第二课注7。 348 2. not that… but that… 不是……而是 3. It is at this creative stage that the application of engineering economics has its greatest " pay off”这是一句“itis…that…”型强调句型,可译成“正是在这个创造性的阶段,工程经济 学的应用有它最大的效果。” 4. on account of their independent commercial status考虑到他们个子独立的经营情况 5. Before the economic evaluation is made each combination of principal particulars has its design features evaluated in terms of capacity, deadweight, trim and stability, and cost. lhJ 中 has its design features evaluated为“have+宾语+补足语(过去分词)”句型,译为“使 其设计特性做出评价”。 in terms of在……方面(意义) 6. in greater depth可译成“比较深入一些地”; in still! greater depth可译成“更深入一些地”。 7. a drop- out from the calculation…drop-out在此为“被略去”之意
Additional Terms and Expressions 1. net present value 净现值 2. required freight rate 需要的货运费率 3. the time value of money 钱的时间价值 4. capital recovery factor 资金回收因数 5. average annual cost 平均年度费用 6. interest rate 利率 7. annual return 年收益 8. annual cost of capital recovery 年资金回 收额 9. present worth factor 现值因数 10. tax rate 税率 11. port days per round trip 每航次停泊时 间 12. round trip per annum 年航次数 13. handling rate 装卸效率 14. vessel investment 船舶投资 15. total costs 总成本 16. depreciation 折旧费 17. maintenance and repair cost 维修费 18. insurance 保险费 19. fuel and lubricating oil costs 燃润料费 20. stores 物料费 21. port charges 港口费 22. cargo handling charges 装卸费 23. administration 企业管理费 24. crew expenses 船员费 25. freight revenue 运费收入 26. complex economic criteria 综合经济指 标 27. transport cost per unit 单位运输成本 28. recovered years of investment 投资回收 年限 29. profit per annum 年利润 30. life of ship 船舶使用年限 Notes to the Text 1. To design the optimal ship, extensive experience is required of the influence of different design features on first cost.这个句子中，主语成分被谓语 is required 隔离，见第二课注 7。 .348. 2. not that…, but that… 不是……而是…… 3. It is at this creative stage that the application of engineering economics has its greatest “pay off”.这是一句“it is …that …”型强调句型，可译成“正是在这个创造性的阶段，工程经济 学的应用有它最大的效果。” 4. on account of their independent commercial status 考虑到他们个子独立的经营情况 5. Before the economic evaluation is made each combination of principal particulars has its design features evaluated in terms of capacity, deadweight, trim and stability, and cost.此句 中 has its design features evaluated 为“have+宾语+补足语（过去分词）”句型，译为“使 其设计特性做出评价”。in terms of 在……方面（意义） 6. in greater depth 可译成“比较深入一些地”; in still greater depth 可译成“更深入一些地”。 7. a drop-out from the calculation… drop-out 在此为“被略去”之意