Ideally you would like the boat to be sitting with the same weight on each of the cradles. That means that you would like to have them forward of the balance point and back the same distance. You can determine this by where it sits on the catwheels balanced. Then, whether you go 2 ft or 6 ft forward and back from there you will be equally distributed weightwise. Now, if you image putting your boat on the trailer and sliding it forward you would like it to sit on the front cradles before it gets nose heavy. Otherwise you will be crashing the bow into the trailer or the ground before it is sitting properly. The back and front cradles should not be separated by more than about 8 ft. While the boat is balanced on the catwheels measure from the cradles to the front of the boat were you would like the cradles, on the trailer, for catching the bow. That is a great way to determine the distance for your boat. Hope this makes sense.