?? X Dimension

ok ok calling all you outboard V20 owners.........i was asked by the guy that is going to rig my motor when the boat is ready. WHAT the X dimension was?????? he said it was the distance from the center of the bottom of the boat to the center of the prop shaft. had never heard of that before.........................if by any any any chance anyone knows. i'll owe you a beer. all kidding aside if anyone knows this one it would help.
thanks ken