For sports mode, you should use the shutter priority (Tv) or automatic (P) mode, with a shutter speed in line with the sport that you shoot: at least 1/20 s for dragon boats, better 1/50s. Faster for action sports. For example, I use between 1/100s to 1/5,000 s for volley-ball, depding upon the availalble light.
If you use SR, you need to ensure that the SR confirmation icon is on before you shoot (The hand symbol in the viewfinder.) It may take 1-2 s for SR confirmation. If you shoot to quickly, your shot may be blurred.
Center-focus is often the best for sport., But wait fro AF confirmation before shooting.
Hope that the comments may help.