Santa Barbara County is home to the largest offshore oil and gas production in California. The relative amount of NOx emissions from crew and supply boats servicing oil platforms compares to entire platform emissions. This, coupled with the need to reduce NOx in response to state and federal mandates, and the need for offshore operators to reduce offset liabilities, created the climate for joint effort with Detroit Diesel Corporation (DDC) to demonstrate the feasibility of on-road low emission engine technology on marine vessel engines. Two vessels were selected for a demonstration program. Specially developed DDC low emission engines were installed in a crew boat and a commercial tourist boat under this program.The program goals were to achieve a NOx emission level of 5 g/hp-hr on both the non-road 8-mode test cycle and under cruise operating conditions. In addition, a further goal was to achieve on-road emission levels for other pollutants. Existing engines in the Santa Barbara area are already controlled to a NOx emission level of 8.4 g/hp-hr through injection timing retard.DDC marine engines use the Detroit Diesel Electronic Control (DDEC) system to optimize emissions and performance under all operating conditions. This paper will describe the special calibration development work performed, along with charge air cooling system modifications to achieve the stringent NOx emission goals.This paper also includes a description of the DDC Marine Data Center and its use in this program. This system logs fuel usage data obtained from the DDEC electronic control modules (ECM) on the engines. It stores engine load information and calculates emission levels based upon calibration information stored in the ECM memory. The use of a satellite communication system to transmit this data to an office location was also demonstrated under this program.