Posted on 08/11/202428/10/2024

How many kilometers per hour is a knot?

The “knot” is a fundamental speed measurement in the world of navigation, both for ships and aircraft. However, for those unfamiliar with navigation, the concept can be confusing, especially when compared to the measurement system we use every day, kilometers per hour (km/h). Understanding what a knot is and how many kilometers per hour it represents is not only useful for those in the nautical or aeronautical world, but also for anyone interested in better understanding speed and distance in sea or air travel.

Origin and definition of the knot

What is a knot?

A knot is a unit of speed equivalent to one nautical mile per hour. Unlike the land mile, which equals 1,609 kilometers, the nautical mile is 1,852 kilometers. Therefore, one knot represents 1,852 km/h. The choice of this measurement is based on geographical coordinates and navigation, since one nautical mile corresponds to one minute of latitude.

History of the use of the knot in navigation

The history of this unit of measurement has its roots in ancient methods of navigation. In the past, sailors used a device called a “nacelle slide”, a piece of wood tied to a line with knots at regular intervals. By tossing the wood into the water, the current would cause the line to unwind, and by counting the knots that passed in a specified time, they could calculate the speed of the vessel. Although modern measurement systems have replaced these methods, the term “knot” remains in use and retains its importance in the field of navigation.

Conversion from knots to kilometers per hour

One knot is approximately 1,852 km/h, which means that to convert knots to kilometers per hour, simply multiply the speed in knots by 1.852. This conversion is useful to better understand the speed of boats or airplanes when translating to metric, especially when buying a new boat.

Examples of common conversion

Below are some common conversions between knots and kilometers per hour for quick reference:

• 1 knot =1,852 km/h
• 5 knots = 9,26 km/h
• 10 knots = 18,52 km/h
• 20 knots = 37,04 km/h
• 30 knots = 55,56 km/h
• 50 knots = 92,6 km/h
• 100 knots = 185,2 km/h

Why is measurement in knots useful?

The relationship with geography

The reason navigators use knots instead of kilometers per hour is due to the direct relationship between the nautical mile and geographic coordinates. Each minute of latitude is equivalent to one nautical mile, which facilitates the calculation of distances on navigation maps, since they are aligned with the Earth’s coordinate system.

Facilitates the calculation of distances in navigation

Imagine you are on a boat traveling at 15 knots in a straight line for one hour. Because the knot equals one nautical mile, you can calculate that you have traveled 15 nautical miles. This is much simpler than converting distances each time between kilometers or land miles, which simplifies navigation operations.

Examples of speeds in knots and kilometers per hour

To help visualize what speeds look like in knots versus kilometers per hour, here are some real-world examples of speeds for both ships and aircraft:

• Cruising speed of a pleasure boat: between 15 and 20 knots (approximately 27,8 and 37 km/h).
• Speed of a fast ferry: between 30 and 50 knots (approximately 55,6 and 92,6 km/h).
• Cruise speed of a commercial aircraft: between 450 and 500 knots (approximately 833 and 926 km/h).
• Speed of a fighter aircraft: up to 1000 knots or more (approximately 1852 km/h or more).

Relationship between nodes and resistance factors

It is important to mention that in water, drag also increases with speed. So, in practical terms, doubling the speed in knots not only means that the distance traveled in the same time will double, but also that the fuel required to maintain that speed will increase due to water or air resistance.

How to calculate distances and times using knots

For those in navigation, calculating time and distance based on knots can be a simple task. For example, if a boat travels at 10 knots for three hours, it means that it has traveled 30 nautical miles. This is because speed (knots) multiplied by time gives the total distance traveled in nautical miles.

Practical example of time calculation in navigation

Imagine you are sailing to an island 50 nautical miles away and you maintain a constant speed of 10 knots. To calculate the time it would take to arrive, you simply divide the distance by the speed:

Estimated Time = Distance / Speed = 50 nautical miles / 10 knots = 5 hours

This type of calculation helps navigators estimate their arrival times and optimize their route.

Factors affecting speed in knots

Climatic conditions

Weather is a key factor affecting the speed of ships and aircraft in knots. Headwinds, ocean currents and wave resistance can reduce or increase the speed of a vessel.

Condition of vessel or aircraft

A well-maintained boat or aircraft generally maintains a more constant speed. However, any type of damage or excessive weight can impact speed, reducing it and affecting fuel efficiency.

Route planning

Planning the route taking into account latitude, prevailing winds and ocean currents allows for more efficient navigation. In aviation, flying in the jet stream can significantly reduce flight time and fuel consumption.

Curiosities about the use of the knot in navigation and aviation

• The origin of the knot:The origin of the knot comes from the method of the ‘basket runner’ used by sailors, a system that consisted of throwing a rope with knots at regular intervals.
• Its global use: today, the knot is a standard measure of speed in navigation all over the world.
• Accuracy in navigation: being based on the nautical mile, a knot is an accurate measure for mapping and routing at sea and in the air.

Understanding the concept of a knot and its equivalence in kilometres per hour allows a better appreciation of speeds in navigation and aviation. A knot is equivalent to 1,852 km/h and is directly linked to the measurement of geographical coordinates, which facilitates calculations on maps and charts. Although it may seem an unintuitive measurement compared to the metric system, the knot provides essential clarity and precision in the world of navigation.

For those unfamiliar with this system, understanding how to convert knots to kilometres per hour is a useful tool. With this knowledge, it will be easier to understand the speed of ships and aircraft and, in general, to better appreciate the planning and timing of international routes.

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