The Iveco marine propulsion diesel engine is lowered into the derrick boat Elizabeth's engine room by the vessel's Mantis hydraulic crane. On Oct. 9, the Norfolk District, U.S. Army Corps of Engineers derrick boat Elizabeth's "green initiative" transformation began with the installation of two new fuel-efficient and EPA-compliant marine propulsion diesel engines. The project includes two companion diesel generators, housed in sound-barrier boxes that significantly reduce noise pollution and exhaust emissions. The eco-friendly engines have a 25-year life span.