A Model for Intact and Damage Stability Evaluation of CNG Ships during the Concept Design Stage

Abstract

To face the design of a new ship concept, the evaluation of multiple feasible solutions concerning several aspects of naval architecture and marine engineering is necessary. Compressed natural gas technologies are in continuous development; therefore, there are no available databases for existing ships to use as a basis for the design process of a new unit. In this sense, the adoption of a modern multi-attribute decision-based method can help the designer for the study of a completely new ship prototype. A database of compressed natural gas ships was generated starting from a baseline hull, varying six hull-form parameters by means of the design of experiment technique. Between the attributes involved in the concept design process, stability is for sure one of the most relevant topics, both for intact and damaged cases. This work describes two approaches to identify the compliance of a ship with the intact stability regulations based on the ship main geometrical quantities. Moreover, a metamodel based on the maximum floodable length concept (damage stability) allows determining the main internal subdivision of the ship. The metamodel outcomes were compared with results from direct calculations on a ship external to the database, highlighting the adequate accuracy given by the developed methods.

LCTC Ships Concept Design in the North Europe- Mediterranean Transport Scenario Focusing on Intact Stability Issues

“…After the unloading of one half of the vehicles in Misrata (4), the stop in Piraeus (5) port provides for the disembarkation of a small percentage of vehicles and the embarkation of a similar amount. From Piraeus, the ship stops in Limassol (6), Beirut (7), Tripoli (8), Mersin (9) and Lattakia (10), from which port sails up to Yenikoy (11) almost empty. In Autoport-Izmit (12) and Gemlik (13) the ship is loaded again and sails up to Salerno (14) at almost full load condition.…”

“…To build metamodels, the Multiple Linear Regression method has already been applied in the concept design phase with good results [10]. The MLR method provides an estimation of the response y of a system as a function of n independent variables x i .…”

“…In previous studies, the GZ curve has been directly evaluated through one or more regression equations including the KG/T as an independent variable [10]. However, this approach encompasses both geometrical aspects (the shape of the cross curves of stability) and mechanical aspects (related to the lightship weight and loading condition).…”

“…A simple method for RoPax has been proposed by [9] based on the definition of KG limit curve. A more complex approach as been proposed by [10] devoted to assess the righting arm curve of CNG ships.…”

A New Design Criterion to Improve the Intact Stability of Galician Small Fishing Vessels

“…It was useful to define the operational limitations of a ship in that situation [22] and impose some other limitations to be applied in other ship types, e.g., Navy ships [23]. New modeling methodologies [24] and Computational Fluid Dynamics (CFD) analysis [25] are being developed, improving ship design and selecting between different alternatives to improve ship stability due to the lack of a previous database or case studies like in CNG Ships. Nowadays, the second-generation stability criteria aim to consolidate the draft guidelines and complete the work at Ship Design and Construction SDC 7 in 2020 [26].…”