General+arrangement+and+LNG+tank+arrangement

Developing the General Arrangement drawings is a task that requires close interaction with most of the other disciplines in a concept study. It is also important to have good knowledge about existing and future rules and regulations which may effect the general arrangement. For Quantum, the LNG tank arrangement was a particular challenge.

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To produce drawings in a pulsating innovating team is a challenging task, involving parallel processes like making drawings, while container arrangement and hull structure continuously changes as a result of design iterations. Frequent project meetings with experts from relevant disciplines like stability, strength, noise & vibration, propulsion, machinery, hydrodynamics and CFD, yard/production, cargo handling and operation are all parts of the process to arrive at the optimal design. In such a process you also need to be pragmatic and not lose sight of the overall goal.

Design iterations of side hull
For illustration, some of the design iterations carried out for the side hull is shown in Fig.1.

1. Initial design: This design was developed in a small group with core competence on ship design and innovation. The initial idea was to design a wide double side, to be used for container stacking.

2. Design Iteration 1: The initial design was further developed in workshops and meetings. Challenges and obstacles from the initial design was identified with regards to strength of side hull and container stacking.

3. Design Iteration 2: A new slender side hull with passageway outside the main hull was proposed, with the aim to maximise the container capacity while achieving enough space for longitudinal piping etc.

4. Design Iteration 3: This iteration was mostly a back and forth discussion on many design issues, such as strength, operation, and maintenance.

5. Design Iteration 4: The final design was based on a holistic approach to all previous iterations, trying to achieve the optimal balance between container capacity, strength, maintenance, operation, and simplicity of construction.

Container capacity
An Excel file that represents the GA/ Container stacking was developed quite early in the project. This file is flexible and available for all project members; easy to test out different configurations, plan reefer capacity and useful for identifying possible challenges. See Fig.5.

General Arrangement
The general arrangement drawing for Quantum is shown in Fig. 2. In Fig. 3 a typical midship section with the new WidedecK™ concept is illustrated. With the WidedecK™ solution the deck capacity increases with two additional rows. This gives a total container capacity of 6,210 containers of which 3,336 is on deck and 2,874 is in hold.

LNG tank arrangement
The main challenge was to locate and arrange the targeted LNG storage capacity of approximately 5,000 m3 LNG, divided on two tanks, each of ~2,500 m3. Cylindrical, pressurized tanks (IGC tank type C) were chosen, due to their proven technology. All LNG fuelled ships operating today use fuel tanks of this type. They could also be made in a double cylindrical shape (Bi-Lobe type) to save space. Prismatic LNG fuel tanks (IGC tank type A, non-pressurized) are under development, and may in the future be used to reduce the space needed for LNG storage.

Cylindrical vertical & horizontal versions of different diameters were investigated, and we decided on two vertical tanks with a diameter of 13m for our concept, based on an overall 50/50 split on MDO and LNG. See Fig.2 and Fig.4.

The LNG tanks will occupy most of the traditional engine room space below the accommodation, but the dual-fuel electrical arrangement gives us the flexibility to utilise some of the space not suitable for containers. Some container slots have to be sacrificed, but this is the case also for pure fuel oil based ships due to new requirements (MARPOL, regulation I/12A). See Fig. 6 and Fig. 7.

All figures can be found in the advanced magazine viewer or in the paper version

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