International shipping is the source of around 3% of global CO2 emissions. Liquefied natural gas (LNG) is currently considered the only reasonable and commercially advanced alternative to petroleum-based ship fuels. Liquefied natural gas can make a significant contribution to the diversification of transport fuels, reduce greenhouse gas emissions from ships and heavy vehicles. The introduction of LNG technology as a drive for inland ships is a complex process. It requires activities in various areas - development, legislation, building infrastructure, construction of new ships or their reconstruction. The biggest problem now seems to be the certainty of investing in the new fleet or their reconstruction. It is therefore desirable to provide shipowners with guarantees that the investment in renewing or reconstruction should be guaranteed. This paper provides a study of reconstruction of the inland tugboat to a dual fuel system (diesel - LNG). As a model vessel was chosen tugboat used by Slovak shipping company. The results presented a comprehensive design of the main and auxiliary engine remodelling, as well as the design of the vessel's tanks and show how the conversion affects the basic navigational characteristics of the tugboat. Finally, the results point to the conversion methodology which is partly applicable to another type of inland tug, considering the individual specificities.