The wave climate along the main transoceanic routes of the North Atlantic sub basin is determined using three different databases: two derived by numerical models in the HIPOCAS and ERA40 databases and one from Voluntary Observing Ships. For each route the distribution of the mean significant wave height along the path is computed as well as the specific scatter diagram. In addition an assessment of the relative wave heading probability is provided. The results highlight a bias in the visual observations especially in the summer and, more in general, for low sea states. The correction of this bias allows better understanding of rough weather avoidance by ships and to determine a storm avoidance correction.

The main routes of ships voluntarily completing meteorological observations across the North Atlantic are detected by the intensity of the geographical distribution of the voluntary ship observations. The routes are then analysed in order to assess the relative intensity of traffic, the seasonal changes and the trend over the years. This paper will provide a better understanding of the North Atlantic trades and the relationship among the different routes, allowing the identification of the busiest areas. A discussion over the impact of routing on the weather that a transoceanic ship can experience during its life is also provided.