Automation is also important to replace the skilled workers. Welding is one of the most important jobs in shipyards, and the ratio of the mechanized welding in Japanese shipyards is 42% in average, and 64% in the most advanced shipyard (Miyazaki 2008). Further development of mechanized welding calls for a breakthrough. Miyazaki (2008) showed some challenges such as mechanized welding inside the double hull structure in the assembly stage, and mechanized butt welding of longitudinals inside the double hull structure in the erection stage. These can be realized through development of small-sized robots which can move through manholes, root gap.
