Wind has a significant effect on a ship. It causes heading changes and leeway. Failure to compensate correctly for wind during berthing is a significant cause of berthing accidents. The difficulty in allowing for wind arises from the variable effect that wind can have on a ship because of changes in a ship’s heading. Wind has special significance in the handling of high-sided vessels such as car carriers. The effect will vary with the relative wind direction and the speed of the ship. Although wind force and direction can be estimated from information obtained from a variety of sources, such as weather forecasts, VTS information, the ship’s own wind instrumentation and personal observation, local conditions can change rapidly and with little warning. Control of a ship can be easily lost during the passage of a squall. There is an obvious need to understand how wind will affect your ship, and how this effect can be difficult to predict. For example, it might appear logical that the effect of wind on a tanker stopped in the water would cause the bow to swing towards the wind. However, experience shows that a tanker stopped in the water will usually lie with the wind forward of the beam rather than fine on the bow. It is especially difficult to predict the effect of wind on a partially loaded container ship and speed.