After conducting research, I could not find any specific information about a boat ramp named Cobb Boulevard Kankakee in Illinois. Therefore, I cannot provide details regarding its width, the body of water it services, or the type of craft permitted on the water. It is possible that the boat ramp has undergone a name change or may not be a designated public boat ramp. It is important to note that there are various other boat ramps in Illinois that provide access to water bodies such as Lake Michigan, the Mississippi River, the Illinois River, and many others.