How fast is 45 knots in mph?

Knots to Miles per hour table
Knots Miles per hour
44 knots 50.63 mph
45 knots 51.79 mph
46 knots 52.94 mph
47 knots 54.09 mph

Why are knots used instead of mph?

Dividing that 14.4 meters by 30 seconds told them that one knot equaled 1.85166 kilometers per hour or one nautical mile. By performing the calculation using the actual number of knots that unspooled, the sailors were able to measure the ship’s speed.