To convert knots to miles per hour (mph) without using an online calculator, you can use the following conversion factor:
1 knot = 1.15078 mph
So, to convert knots to mph manually, multiply the number of knots by 1.15078.
For example, let's say you have a speed of 50 knots:
50 knots * 1.15078 mph/knot = 57.539 mph
Therefore, 50 knots is approximately equal to 57.539 mph.