I was trying to calculate the required lead of a shot based on the speed and length of the targeted ship. In the calculation, I realize some thing interesting. I roughly record the time for my kongo to travel a distance of my firing range (19.35km) is about 3m55s. Based on this result, the speed of the ship should be 82m/s (>160knots)! However, the speed of my ship shown in the indicator is just 30.3knots. I understand the purpose of this distance scaling. However, this makes the lead calculation impossible if the scaling factor is unknown. Any one knows the solution? Thanks in advance.