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1 Requirements & constraints Before starting the designing it is important to identify the requirements and constraints of the concept to be designed. In the first part of this report the concept of river-sea shipping is being proposed. This concept originates from the market and/or product in these markets. In this case first the concept of river sea shipping is chosen followed by the decision for transportation of the vehicles. In chapter four is stated that the river-sea shipping concept should consist of a ship and a service, which together can be characterized as the design of the concept. The design will be part of the environment it functions within, so designing the ship and the service will be performed taking the environment into account. Figure 8.1 elaborates on this in a schematic way. Requirements originate from the market and from the product and are being imposed on the concept as a whole. All of these requirements imposed can be specified towards a specific requirement on ship or service. Constraints are mostly imposed by its environment. Thereby most important characteristic of a constraint is the fact that it is something that must dealt with in the design, but the designer cannot influence these constraints. This chapter deals first with the different requirements imposed on the design of the ship and the service of the river-sea shipping concept. Next to this the constraints on the design are identified. Market/Products Concept Ship Service Design Environment Figure 8.1: Requirements and constraints during the designing phase 1.1 Requirements It is essential to identify the requirements that should be imposed on design of the ship and the service. With identifying requirements it will be possible to make clear what the specific need is and how a requirement should be stated to describe the specific need. When the requirements are identified designing can be initiated. During the designing process the requirements should be actively involved so the design should fully fulfill all requirements stated before. After the design these requirements makes it possible to check if the final design fulfills the identified requirements. Depending on the level detail it is possible to indentify different requirements: requirements on the highest level of the concept (the ship should float), but also on the tiniest sub-system of the ship (the light should be switched on or off). This paragraph will handle the requirements on a concept level and how these requirements influence the design of the ship and service. For a complete overview of the requirements identified with this application of river-sea shipping see appendix X.X. Damage on vehicle should be minimized Loading and unloading should be done in minimal time Availability should be maximized Reachebility in the corridor should be maximized The concept should be highly costs competing with the current ways of transport The concept should be highly time competing with the current ways of transport Pushing vessel should be changed when going sailing on sea and vice versa The concept must be durable Iets van conclusive dat alles van elkaar afhangt en dat er een afweging gemaakt moet worden tussen time/costs/damage 1.2 Constraints Constraints are just like requirements very important during design. Most constrains on the ship design are imposed by natural, physical characteristics of the river that is being used for navigating. On the contrary no constraints on the ship design imposed by the sea on the route of transport are found. Another group of constraints have a legal character where by a distinction can be made between legal constraints on the ship and the service design. Last group of constraint originates from the market: these are mostly imposed on the service design. These three groups of constraints will be elaborated in the following paragraphs. 1.2.1 Physical constraints For a ship that is navigating on a river, there are a couple of physical boundaries that limit the choice of parameters of a ship. In general these boundaries limit the dimensions of the ship. For the sea part of the transport service, there are boundaries as well, but they are irrelevant when compared to those of the river. The following table shows the boundaries that are valid for the Rhine, up to Bonn. Parameter Limit Caused by Breadth 11,40 Only for Dortmund, breadth of a lock Draught 3,5 Depth of the river Free height 9,2 Fixed bridge Table 1: Physical boundaries for the Rhine, up to Bonn 1.2.2 Legal constraints The constraints of the design follow from rules and regulations of governmental institutions that have a legal position in the operational area. For the river Rhine that are the Dutch and German government and for the part on the North Sea that is the International Maritime Organization (IMO). The Dutch and German legal requirements for inland navigating ships are aligned, so there are not a lot of differences. The Dutch regulations are issued in the “Rijnvaart politie regelement” and “Binnenschepenwet”. Besides a lot of specific rules, there are some rules that really bound the solution space. Table 2 shows these regulations, the columns show the type of inland ship it involves, the parameter or item it involves and the limits. Type of ship Parameter Limit Inland Length 135m Breadth 22,8m Line of sight Empty ship, 50% stores 250m from wheelhouse Stability GM minimum: 0,5m or 1m in case of unlashed containers Minimum speed Capable of 13km/h through the water Freeboard 0,15m, 50cm extra if no hatch-covers are applied Crash bulkhead Between 0,04*L and 0,04*L+2 meters Inland L>110m Propulsion Double configuration Double bottom 600mm height, throughout the length Push barge Crash bulkhead Not necessary when barge is strong enough Length of convoy 269m upstream, 193 downstream, max barge length 110m Push boat Length 40m Engine power Max 4500kW Table 2: Rules and regulations for Rhine Navigation, up to Mainz Vaartijdenwet Legal constraints voor op zee uitwerken als loadunit gekozen is. 1.2.3 Market constraints Origin and destination of vehicles Production volumes 1.2.4 Requirements There are three parameters that have the most influence on the operational profile: the speed, the capacity and the ability to load and unload autonomously. The first two are also bounded by the constraints and shown before. The maximum size of the box the ship has to fit in under water is 135m*22,8m*3,5m. Combined with a fleet average block-coefficient of 0.8, the maximum displacement of the ship will around 8600 tons. Assuming that for cost effectiveness on the sea, the scale advantages are very important, the ships size should be maximized. Especially the length is very attractive to maximize, since the total resistance, and therefore fuel consumption, is smaller for a longer ship than for a shorter one, everything else being the same. If it is decided to keep Dortmund as a possible stopover, the breadth needs to be reduced to 11,4m which results in an extremely narrow ship that may suffer severe stability problems. However, a ship with a breadth of 22,8 meters may have trouble with accelerations due to sea-state. Minimizing the structural weight, or lightweight, of the ship leaves a maximum cargo capacity. Therefore innovations in construction of the vessel should be investigated. Sailing a ship along a river has a lot of consequences for the design, a lot of requirements and constraints are specifically determined by the fact that the ship has to be able to navigate on the strict boundaries of the river. This paragraph will focus on shaping a box in which the ship has to fit, together with the rules and regulations that apply on the internal structure of the box. The requirements follow from the desired operational profile and the constraints from rules and regulations of different governmental institutions.
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