Commercial river ship presents good alternative to road transportation in terms of carbon dioxide emissions but not obviously concerning other pollutants. A solution to reduce fuel consumption and respect future pollutant norms can be to use a combined serial-parallel hybrid architecture. Engines dedicated to road transportation with their depollution systems can be used if high downsizing is performed. This paper investigated this possibility focusing on the management of a such hybrid architecture. A parametric studies is then presented to evaluate the fuel economy of such solution.