See you have to look at the blow boaters for this one. One mile per hour to us is no big deal. One mile per hour to them is HUGE. The more perfect that they can get the bottom on the boat they faster they go. The finner grit that they can sand it to the faster it will go. They used to sand with 600 grit and attempt to get the layer of water to stick to the boat. Now they are finding out that going with the much higher grit papers. IE 4000 grit and higher that they are getting more speed.