The bunks on your lift need to be moved closer together, effectively raising the boat above the i-beam.
Measure the height from the i-beam to the top of the bunk. Then estimate how close the bunks must be together to raise the keel of the boat 1 to 2 inches above the i-beam. Err on the side of bunks set closer together, thereby raising the boat up more. When I set my bunks, I calculated these measurements myself (do NOT rely on the lift guys to do this for you...they will most likely get it wrong!).
Then, have the lift guys adjust the bunks while you pull the boat off/on the lift. When I set mine, one guy stayed in the water off the bow to make sure the keel did not hit the i-beam as the lift started upward. If it looks like it's going to hit, lower the lift again and move the bunks closer together until the clearance is 1-2 inches.