Boat Speed Calculator
Convert between different boat speed measurements and understand marine velocity units
Different speed units are used in marine navigation and general transportation:
- Knots (kts): Nautical miles per hour, standard for marine navigation
- Miles per Hour (mph): Common in the US and UK
- Kilometers per Hour (km/h): Standard metric unit
- Meters per Second (m/s): SI unit, used in scientific contexts
Key conversion factors between different speed units:
- 1 knot = 1.15078 mph
- 1 knot = 1.852 km/h
- 1 knot = 0.514444 m/s
- 1 mph = 0.868976 knots
- 1 km/h = 0.539957 knots
- 1 m/s = 1.94384 knots
Note: These conversions are based on the international standard nautical mile (1,852 meters).
Boat speed calculations are essential for:
- Navigation planning and route timing
- Fuel consumption estimation
- Weather routing and safety considerations
- Racing and performance analysis
- Compliance with speed regulations
- Always use knots for marine navigation
- Consider current and wind effects on actual speed
- Monitor speed through water vs. speed over ground
- Use GPS for accurate speed measurements
- Keep speed logs for performance analysis
Why are knots used for marine navigation?
Knots are used because they directly relate to nautical miles, which are based on the Earth's circumference. One nautical mile equals one minute of arc on the Earth's surface.
What is the difference between SOG and STW?
Speed Over Ground (SOG) is your actual speed relative to the Earth, while Speed Through Water (STW) is your speed relative to the water you're moving through. They can differ due to currents.
How do currents affect boat speed?
Currents can either add to or subtract from your boat's speed. A following current increases your SOG, while an opposing current reduces it, even though your STW remains the same.