Closing Window

The weather window is closing slowly. Not the wind and sea, but this time the period of the swell is part of the problem. All vessels can and will roll and pitch. The difference in behavior in sea and swell is caused by the period (or frequency) of the waves and swell. For instance; a swell period of 11-13 seconds makes large vessels roll and pitch where smaller vessels like our tug hardly feel any movement at all. The average speed of swell is 25 knots. That is 12 meters per second. So, a swell period of 11-13 seconds means a wavelength of about 150 meters and that is exactly the same as the ships length of the Hermod. Swell or no swell, the window is closing anyway because a lot of wind is expected in and after the weekend. On the picture you can see exactly what is going on, apparently calm seas (you can't even see the swell) and clouds predicting rain and wind.