The research was carried out by numerical methods of small scientific trimaran boat with ADCP-profiler as ship's appendages in the range of Froude numbers from 0,19 - 0,316. For тnumerical simulation was used the FineMarineTM software. Numerical modeling was performed for a trimaran without an installed ADCP-profiler and for two mounting options at different locations along the length of the trimaran and in depth. Two types of ADCP-profiler fastening were studied. Mounting the device in a parallelepiped ship trunk has a greater influence on the resistance and moment My. With increasing speed, the area of the wetted surface for "free" mounting does not change much. For mounting "in the trunk" between trimaran's hulls the shape of the wave surface changes quite significantly, which leads to a redistribution of the buoyancy forces along the length of the boat.