Lightship weight and its distribution have significant influence on the intact/ damage stability and longitudinal strength of the ship. In this study, the range of limiting lightship longitudinal and vertical centre of gravity for different types of merchant ships have been determined. The merchant ships considered are bulk carriers, crude oil tankers, liquefied gas carriers, container ships and pure car carriers. Detailed hull form and general arrangement layout of the merchant ships were

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... oped. Applicable rules and regulations and design considerations for each type of merchant ships were considered for this purpose. The principal dimensions, form coefficients, powering, stability and statutory rules and regulations are matched to the ships in service. At this stage, different rules and regulations concerning ship's stability and trim were considered. Finally, after deducting the vertical and longitudinal center of gravity of the deadweight components (cargo, fuel and fresh water), the limiting lightship vertical and longitudinal center of gravity are determined. Study on the lightship characteristic of merchant ships Vishwanath Nagarajan, Om Prakash Sha 38 passenger ships, containerships, car carriers, LNG and LPG carrier. An important feature of volumetric carriers is large hold volume. In ship design process, selection of length, beam, draft, depth, block coefficient, prismatic coefficient and displacement are important elements. This order is applied to deadweight carriers and logically modified for volumetric carriers [1]. The basic characteristics of different ship's lightship components, typical sizes and percentages of weight groups for merchant ships were estimated [2] and updated by Papanikolaou [1]. In this work [1], the variation of ship characteristics have been presented with respect to ratios of principal particulars ( / LB , / BT , / LD etc). Statistical analysis of upper and lower boundaries of hull form coefficients and ratios of main dimensions for merchant ships were carried out by Strohbusch E. and updated by Papanikolaou [1]. As per statutory regulations [3] , the permissible variation of a ship's lightship displacement is less than 2% of the lightship displacement and of the lightship's longitudinal centre of gravity it is less than 1% of ship's length [3] . If the variation is higher, then an inclining experiment needs to be carried out to determine the new lightship vertical centre of gravity. This shows the influence of these parameters on the ship's stability. Sensitivity analysis of the probabilistic damage stability regulations for Ro-Pax vessel was estimated [4] . Investigation of one large Ro-Pax ship was carried out, to document the underlying and emerging trends of Ro-Pax ship design which will help the designer at the early stages. Very few ships have been designed till date on the basis of probabilistic subdivision regulations. Typical large Ro-Pax vessel was investigated with variation of parameters, like number, position and optimization of transverse bulkheads. Also the presence and position of longitudinal bulkheads below the main vehicle deck, the presence of side casings, and the height of the main deck and double bottom were considered. Probabilistic damage stability framework was developed to enhance passenger, ship safety in the maritime industry [5] . The probabilistic framework of the new rules for damage stability offers flexibility and added degrees of freedom for designers to enhance safety cost-effectively. Now the trend is towards probabilistic and risk based frameworks to address ship safety in a scientific manner. Therefore, it is important to understand the principles and the intention of the ensuing rules and criteria. The problems faced by the marine industry to cross the bridge from rules-based to risk-based design need to be put into practice. This paper [5] demonstrates that requirement of scientific and technological developments are in hand for risk-based design to be fully implemented in the maritime industry. The optimization of diesel electric machinery system for conceptual ship design was presented to support selecting the configuration of diesel engines in a machinery system [6] . The model aims at minimizing investment and operational costs over the ship's lifetime when the ship's operational profiles are assumed to be known. The load distribution on the engines is considered in the model to ensure that required demand is met with sufficient power supply for all future operational states. A method for fuel consumption calculation is presented, based on determining optimal load distribution amongst the engines generalized specific fuel consumption curve. A parametric method was developed to determine the steel weight for each main structure to estimate the global design factors with a lower average error than other methods [7] . This measurement decisively influences the weight calculation and is also a critical cost item in the tender of a new shipbuilding contract. The principal component analysis is applied to find the principal influence parameters, including the global and local design factors, and to calculate the weighting values for each parameter. The obtained weight distribution to support the various aspects of preliminary design, help to determine the center of gravity, the design of the ship lines and ship performance evaluation. Cudina and Bezic [8] evaluated the economics of operating reefer vessels and container ships for carrying same amount of refrigerated cargo. Detailed general arrangement design of a reefer ship and a container ship were carried out. Fuel consumption for maintaining the cargo temperature and for completing similar voyages were compared. It was concluded that the reefer ship's