For most purposes, however, the increased play and river-running performance will more than offset the loss in speed. For most paddlers this will not be a big problem, as whitewater kayaking is primarily a downriver sport. Keep in mind that the difference in speed between a 13 foot displacement hull boat and an 8 foot planing hull boat is only about 2.5 miles per hour. That's not too bad when you consider all the advantages that the new boats offer. The sharpness of the edge and where it falls on the boat both have significant impact on the performance of the boat.
Sharp edges can grab the water, a benefit for playboating, but it does make the boat less forgiving.
Soft, rounded edges are forgiving in big water and keep the boat on top, but it will be more difficult to get them under water to do rodeo tricks. When the edges are positioned low on the boat, vertical moves can be initiated more easily, but the trade-off is that the current may grab an edge inadvertently and flip you over. Higher edges ride up out of the water and grab less, which is great for river running. To initiate vertical moves, though, the paddler needs to apply a little more boat control. Hull type There are two-planing and displacement.