Keeping in mind the close date for publishing the list of ports included in the MoS network we are going to analyse what type of vessel is going to fit best in some of the proposed ports, for ensuring a real modal shift. Once understood the sea transport importance, the sea conditions and specifically the wave highness analysis, is the topic to be dealt in this paper, as a contribution to recommend the ship better fit on a route, keeping in mind her sensitivity to sea and waves.