Abstract : As an element in the Coast Guard s (CG) compliance strategy for decreasing greenhouse gases (GHG), and increasing the use of alternative fuels, the USCG Research & Development Center (RDC) tested a blend consisting of 16.1 percent biobutanol by volume (BU16), with regular E0 gasoline. BU16 is a renewable alternative gasoline fuel. The RDC tested BU16 on a USCG 38 Special Purpose Craft Training Boat (SPC-TB) powered by twin Mercury 300 HP Verado engines at CG Training Center Yorktown, VA. Butanol was obtained from Gevo Inc, currently the sole United States supplier, working through a local distributor who blended and delivered it. Fuel quality was monitored throughout the test. Before the operational test, Mercury Marine conducted materials testing to examine engine compatibility with BU16, bench testing to measure emissions, and on-water testing to assess engine performance. Operational testing was conducted from 1 July 2013 to 31 July 2014. The SPC-TB underwent typical training missions and ran periodic baseline tests using E10 gasoline and BU16 for comparison. The RDC collected and analyzed engine performance data and crew observations of boat performance and maintenance. Details of the testing, and the conclusions and recommendations are included in the report.