Not All Boat Wakes Are Alike (IMAGE) Norwegian University of Science and Technology Caption The boat is moving at the same speed in all of these photos, 50 cm/s. According to Kelvin's theory, all three of these wakes should look the same, but they don't. Try to count the transverse waves behind the boat (the little white spot at the top of each image). Left: Skewed waves. Here, the surface is not moving, but there's a current under the surface. Centre: Same speed, also with the surface at rest, but for this case there's an underwater current against the direction of motion. Right: For this case, the boat and the underwater current are moving in the same direction, still with no surface motion. (This is shortly after the boat started moving, so you can see that the waves are closer together at the back). Credit NTNU Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.