This paper presents the preliminary analyses devoted to the development of a new fast-craft concept, different from typical off-shore crafts, able to reach very high speed despite its main dimensions and displacement. In particular, the analysis is focused on “deep V hull shapes” of overall length of about 40 m and a range of operative speeds up to 60 kn. Many issues can be found during the design phase for a new concept boat. Moreover to classical design problems, well studied in naval architecture, new issues and peculiarities arise for these type of very high speed craft. One of these new relevant problems is related to the evaluation of the calm water resistance curve, for which the availability of data and reliable methodologies should be deeply investigated due to the extreme conditions analyzed. The correct drag prediction is a key point, for instance, for the evaluation of the on board installed power, necessary to gain the maximum speed required and, in turn, for the evaluation of the total boat weight (being the main engine one of the most significant contributor) on the light of its strong influence on the boat trim and consequently on the drag. Similar considerations have to be carried out for the seakeeping performances, in particular for what regards the vertical motions and the evaluation of the Motion Sickness Index. In these extreme conditions, actually, very high vertical accelerations have to be expected and consequently strict operative sea states limitations have to be imposed.