During the past decade, welding remained the main technological procedure for joining steel components in shipbuilding industry. Though it has great benefits, welding is an aggressive process that introduces high stress and strains in the joined materials, causing distortion. Finite element method is an important instrument for predicting how structures are behaving under thermal loads. This paper is focused on studying the behaviour of small thickness ship panels, under straightening treatment, by performing thermal-structural-elastic-plastic analysis in Femap/NX Nastran. The proposed panel is tested under three different thermal loadings in order to study stresses and residual distortion.

Since welding started to be used on a large-scale basis in engineering, distortion has become a stringent problem for the industry, mostly for shipyards. This paper aims at bringing together the result of large amount of research on distortion and mitigation techniques, in order to support further practical research on the topic. Phenomena, such as mostly used treatments for reducing distortion were explained in detail. In addition to this, inherent strain theory was presented for offering a starting point to those who shall perform thermal analysis in welded structures.

The catamaran resistance is an important hydrodynamic performance that must be studied starting with the initial design stage. In this paper, both theoretical and experimental analysis of a Danube Delta passenger catamaran resistance was developed. The method proposed by Sahoo et al. for catamaran with rounded bilge was applied to estimate the ship resistance. Experimental model tests were performed in the Towing Tank of “Dunarea de Jos” University of Galati, in order to determine the optimal distance between the hulls of the catamaran. Important differences were observed between the theoretical and experimental results.