The best replacement for knots is mph.

The best alternatives to knots are rated as following:
★★★★★  mph
★★★  miles per hour
★★★  miles
★★  mph conversion
★  nautical miles
★  kilometers
★  miles per hour conversion
★  kph
  m/s
  mach
  km
  wind speed
  mile per hour
  km per hour
  km h
  mach speed
  meters per second
  kilometers per hour
  m s
  lumps
  trigger points
  beaufort
  mph wind speed
  double overhand knots
  spasms
  zulu knots
  crimps
  kmph
  miles\/hour
  adhesions
  km/hr

Your alternative for knots is not listed? Suggest!
Speaking about knots, one probably shouldn't forget about rope.

Other search terms related to knots and their ratings are:
★★★★★ rope
★★ loops
★ 2 ropes
bruising
You have in mind a companion for knots and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of knots in all years. Click on graph for more.
knots
mph
miles per hour