Jumbo Maritime is a heavy lift shipping and offshore transportation & installation contractor. The Fairplayer is one of the J-class vessels that is capable of performing offshore installation work. The two 900 ton Huisman cranes can lift up to 1800 ton combined, but the insufficient static stability of the Fairplayer results in a maximum lifting capacity of 1000 ton in offshore conditions. This limited lifting capacity in offshore conditions is a missed opportunity to make use of the Fairplayer in a wider segment of the offshore installation market. In this research, the increase of static stability is obtained by the use of a sponson. A sponson is an extension of the hull, which can be seen as a local widening on the side of the Fairplayer. This sponson is expected to result in an increase of the total resistance. The goal of this thesis is to investigate the influence of the position and shape of a sponson on the Fairplayer with respect to the resistance. The influence of the position and shape of a sponson is analysed by the variation of the longitudinal position, the vertical position and the length over width ratio of the sponson. A combination of the Holtrop-Mennen method and the potential flow program RAPID is used to give an estimation of the increase in resistance. RAPID is used to calculate the influence of the wave-making resistance of the Fairplayer, whereas the frictional resistance is calculated according to the ITTC-57 flat plate friction formula and a form factor. It can be concluded that the position of the sponson turned out to have a significant influence on the wave pattern and therefore on the wave-making resistance of the vessel. The sponson can be positioned in a way that the wave system generated by the sponson interferes with the wave systems generated by the vessel. With this combination of the Holtrop-Mennen method and RAPID, a position of the sponson is found where the increase of the total resistance is minimized to 7%.