Currently, the shipping industry accounts for 4% of the fuel consumption around the globe. With the growing demand for electrification in land-based transportation and infrastructure, contributions to emissions inventories from large ocean-going vessels (OGVs) will continue to become more significant as they account for a larger portion of global fuel consumption. This body of work is an investigation of the real-world effects of modern emissions standards, and fuel regulations, on large ocean-going vessels (OGVs) used in the commercial maritime industry. It is comprised of sample system design and implementation, various studies on the effects of CARB regulated marine fuel, the difference between the regulated emission standards and the real-world emissions of Tier III OGVs, and the effect of vessel speed reduction (VSR) on Tier III emissions.Emissions sampling systems were designed and deployed to two field campaigns in support of this body of work. The first campaign consisted of in use emissions measurements of a steam turbine driven container ship predating emissions regulations. OGVs typically have an operational lifetime of up to 50 years. Therefore, a continued understanding of changes in emissions profiles for older vessels using new fuels is a critical part of future emissions modeling efforts. The second campaign evaluated the emissions profiles of two new build Tier III vessels, the newest EPA technology class for marine emissions standards. The primary emissions were measured and modal data was analyzed to determine the air quality effects of Tier III emissions control technology on OGV emissions.