How Does Speed Affect a Planned Ship Route?

If you want to study how speed changes a planned ship route, use this process.

Step 1: Open MarineRadar.

Open MarineRadar and access Route Planner.

Step 2: Choose the starting point.

Select the location where you want the planned voyage to begin. This could be a major port or another location on the map.

Step 3: Select the destination.

Choose the final destination. The planner can now create the basis of your planned journey.

Step 4: Add intermediate stops.

If the vessel is expected to call at other ports, use Add Stops.
For example:
Singapore → Colombo → Port Said → Rotterdam
This makes the scenario more representative of a multi-port shipping voyage.

Step 5: Select the date and time.

Enter the planned departure date and time. This is useful because maritime conditions can change over time.

Step 6: Set the expected speed.

Enter the speed you want to test.
For example, start with 12 knots.

Step 7: Review the route.

Look at the complete route and its estimated journey.

Step 8: Change the speed

Now change the speed to 15 knots. Review the result again.

Step 9: Test another speed.

Try 18 or 20 knots and compare the result.

Step 10: Compare the scenarios.

Now you have several versions of essentially the same voyage.

For example:

Speed interacts with several other factors.

1. Fuel consumption

This is one of the biggest considerations. Ships need propulsion energy to move through water. As speed increases, the energy requirement generally rises much faster than the speed itself.

IMO GreenVoyage2050 explains that propulsion power has a strongly non-linear relationship with speed. It also notes that lower speed can produce significant fuel savings, although the vessel then spends more time at sea.

Therefore, operators may need to balance:

Speed + fuel + voyage time + schedule

rather than simply selecting the fastest possible speed.

2. ETA

Speed directly affects the expected arrival time.

MarineRadar uses vessel information such as speed and ETA when users track actual ships. The platform also explains that ETA can change because speed, route, AIS updates, weather, and other conditions can affect the voyage.

For example, suppose a ship is expected to maintain 15 knots.

If it later slows because of weather or operational conditions, its arrival time may move later.

This is why an ETA should be understood as an estimate, not a permanent promise.

3. Weather Can Change the Effect of Speed

Weather is another major factor. Wind, waves, and ocean currents can affect the power required to move a ship at a particular speed.

The IMO explains that these conditions should be considered during voyage planning because they can influence propulsion requirements and route choice. Longer voyages also provide more opportunities to choose routes that avoid unfavorable weather.

Imagine two planned routes:

Route A: 2,000 nautical miles
Route B: 2,150 nautical miles

At first glance, Route A appears better because it is shorter.

But suppose Route A passes through stronger adverse weather while Route B provides a more favorable route.

4. Speed Can Affect Route Decisions

Speed and route are connected.

Suppose you have two possible routes:

• Route A

Shorter distance but potentially more difficult conditions.

• Route B

Longer distance but potentially more favorable conditions.

A route planner can help you visualize these scenarios, but real-world voyage planning needs additional information and professional judgment.

MarineRadar’s own guidance emphasizes that ships do not always follow the shortest route. Weather, traffic, port schedules, canal availability, safety considerations, intermediate stops, operational decisions, and speed can all contribute to route differences.

5. Speed and Canal Choices Can Work Together

MarineRadar Route Planner also provides an Avoid Canals option. This creates another useful comparison. Imagine a voyage where a canal provides a shorter connection between two regions.

You could create:

Scenario A: Canal route at 15 knots

Then:

Scenario B: Canal-avoiding route at 15 knots

Then:

Scenario C: Canal-avoiding route at 12 knots

Now you are comparing two different variables:

Route choice + speed

This is useful because a longer route may require more sailing time, while a higher speed may reduce the additional time.

MarineRadar specifically recommends experimenting with different settings to compare route possibilities.

6. Speed Can Matter for Multi-Port Voyages

Speed becomes even more interesting when a ship has multiple stops.

Consider:

Shanghai → Singapore → Colombo → Rotterdam

The vessel is not simply traveling from Point A to Point B. It has several stages.

If the vessel travels more slowly on the first leg, that can affect its expected arrival at the next port. Port schedules and subsequent voyage stages can then become important.

MarineRadar’s Route Planner allows users to add stops and set speed, making it possible to build scenarios that better represent multi-port shipping journeys.