We have not really talked about how the speed changes and the boundary layer changes around the ship hull. There will be additional effects which have not been included in this analysis of shallow water resistance. So, actually the dropping speed that is estimated using this method is valid only up to certain amount of restrictions. If the restrictions increase, then the drop in speed may be more. Why does this drop in speed important? Why do we talk about this? If my vessel is not going to move in shallow water, why do I talk about this?