Focus problems

I have been photographing powerboats racing for a number of years both the land and in the back of small and large boats at sea.
I have a Canon 40D and 60D ,most of my lens are F 2.8. Now for some unknown reason my images are not to be as sharp as they should be ,any suggestions on set up, metering etc.

Too many variables.
Post some images (with exif intact) that show the problem you are having.
You need to help us to help you.

Hope you can see from these shots.
Taken at Rouen 24 Hr race with a Canon 60D and 100-300 2.8 sigma .
F/4;1/2500 sec; meter mode pattern.