The researchers investigated the environmental impact of small boats throughout their life cycle, focusing on stages up to construction. They studied a 13-meter landing craft and measured its impact on the environment using a method called Life Cycle Assessment (LCA). By analyzing data from a shipyard, they found that the boat's emissions of CO2, NOx, SOx, NMVOC, and PM, as well as its diesel oil consumption, were major contributors to environmental effects like acidification, eutrophication, and global warming in the air we breathe.