Optimized Weather Routing Makes Shipping Cheaper and Safer


Published Jun 29, 2021 3:10 PM by DTN

Remko Vermeer, one of the former seafarers employed in the continuous shift service at DTN, is more than familiar with weather information and weather routing from experience.

Before Vermeer joined the weather room at DTN, he was a first mate for Spliethoff. But he decided to turn down a master's position due to the administrative workload and responsibility the job entails.

DTN has undoubtedly benefited from the views of seafarers like Vermeer in the weather room. Before they joined the broader weather room team, for example, charts did not always have enough detail; masters would say things like: 'Your advice guides me past an island, but there's a big sandbank in front of it; what do I do?' It was ample reason to improve maps and buy ECDIS.

A world view

Vermeer is in the weather room; in front of him, three screens present views of the global weather. The screens show air pressures, wind trajectories and wind forces, currents and details about waves and swells. To see 12, 24, 48, or 72 hours and - if necessary - as much as nine days ahead, he only needs to press a few keys.

On the screen is a new stratum. But the screen predicts that it will develop wind speeds of 55 knots over the next few days. The screen displays the expected trajectory (80 to 180 degrees) and the speed (7 to 11 knots). It will probably not reach the 63 knots, or 117 km/h, required for a hurricane, but others have developed from similar systems over warm water last year.

"Breeding grounds for hurricanes include the ocean between Africa and the Caribbean, the area of ocean west of Panama, and the region of sea between Japan and Papua New Guinea. We can recognize those systems because they don't have fronts as normal strata do. They are drains, sucking in everything,” Vermeer explains.

A safe distance of 300 miles

Routing around tropical systems assumes a safe distance of 300 miles to the eye of the storm. "We need to consider the type of ship when recommending a route because our advice depends on the mutual velocities and the ship's destination. We might advise sailing dead slow for half a day, stop sailing entirely, or, the exact opposite, shift from eco speed to greater velocity. The first or second case may delay a ship for days; in the last, it will reach its port sooner but will have used more fuel,” he says. “The client's response depends on the sort of ship. For some ships, stopping for a short while might be an option, but it's a different story for vessels with a tight ETA."

An average five-day forecast in normal circumstances can be reasonably accurate. But Vermeer sticks to 48 to 72 hours when dealing with hurricanes: "You can't always predict what such systems will do the next day, so we send the masters extra updates every six to twelve hours."

What is the best option?

"Many shipping companies use DTN SPOS, but not all ships buy our route advice," Vermeer continues. "However, the most recent data might not always be available to them, due to the limitations of their onboard satellite communications. Our product RouteGuard always uses the most up-to-date datasets."

Vermeer is fully aware it's challenging to prove the advantages of routing – including lower fuel consumption. "Try and prove that a certain loxodrome or a different passage is better or worse. There are so many variables, which makes it hard to compare two journeys and the choice of route can make a huge difference on an ocean crossing. If the ship arrives at a point earlier, or later, on a route, how will the wind and swell be then?"

Masters passing Skagerrak on their way to the east coast of the United States sometimes ask for advice for the next part of the route. "They can pass just above the British Isles or sail through the English Channel." Vermeer adds, "In theory, a master can knock 35 hours off his journey if he doesn't go through the English Channel, but the weather can be worse on the alternative route, so we expect a slower speed, cutting the time saved down to sixteen hours."

Work it out yourself or take advice

The DTN standard shipping product is SPOS, which masters can use to collect weather information themselves. The shipowners decide which functions are available onboard. DTN has over 5,000 daily users for that product. "Worldwide, there are several sources for weather information throughout, and DTN combines them in our model," Vermeer reports. "We give a certain weight to areas in which separate models perform better after verification. It involves a few percentage points of difference."

Other products are RouteGuard, onshore weather routing, and FleetGuard, with the ships reporting to the shipping companies' and charterers' headquarters via a website. "All the data is recorded and used in their own performance systems, if they have them, to optimize the ship's operation costs; it helps them decide when a hull needs cleaning, or a propeller needs a polish, for instance. To do that, a ship's performance must be gauged in calm weather. Nonetheless, theory and reality don't often match, because the weather is always a major variable."

Pennywise and pound foolish?

The main driver behind weather routing is reducing costs, such as ETA, laycan, and fuel consumption. Shipowners do understand the importance of safety, but everything is becoming more and more competitive. Shipowners typically know how far they can push their ship; charterers are more inclined to rely on routing advice.

However, competition still affects routing choices, particularly in the bulk carrier market. Sometimes, there is only a facsimile on board, and the master is entirely dependent on the seafarers at DTN for routing advice. At times like that, they wonder why the charterer doesn't ask the shipping company for SPOS; the master can do his routing. At current SPOS subscription prices, a container ship using 15 to 25 tons a day will typically cover the costs by saving ten tons of heavy oil.

This calculation is based on seven days voyage for container ships that sail at more than 20 knots, to 14 - 15 days, at a cruising speed of 10-11 knots on an ocean crossing from Rotterdam to New York. The vessel type will impact the savings timeline. Ocean-going tugs only do 5 knots at most and make huge detours for the sake of the tow's safety. A strong tailwind might be favorable for a freighter, but a tug captain can't allow his tow to overtake him.

DTN checks its weather forecasts retrospectively. In the weather room, there is a screen that reveals the accuracy of onshore-weather reports. This information is added to historic data to improve the weather models further. Globally, there are plenty of data buoys that pass on details. Oceans are watched by satellites; offshore structures and ships are often equipped with automatic weather stations. Masters also still send weather information to the KNMI. But even so, there are still large parts of the oceans that are not covered.

Measuring and reporting at two heights

In response to questions from masters like: "Why are we measuring stronger winds here than the forces you mentioned?", DTN has started presenting wind forecasts in a new way. "We only used to report wind at ten meters up, the average for ten minutes, but often onboard, the wind sensors are installed much higher, so now we make forecasts for fifty meters up too", Vermeer explains. "Wind to a height of up to ten meters has the most impact on the condition of the sea, but fifty meters is more recognizable for SPOS users and gives a more detailed picture. Moreover, we can also forecast gusts at ten and fifty meters up and produce risk predictions."

The forecasts are even more specific if the orographic effects are taken into account. "At the Strait of Gibraltar, the Strait of Dover and in the Norwegian fjords, winds accelerate due to geographic narrows. The effect is not as obvious in model data, so if force seven or eight is predicted for Gibraltar, we add: bear in mind it could be eight or nine."

There are scarcely any clients who ask for forecasts for the Polar regions. "Very occasionally, someone will ask for a route, but in reality, the Russian pilots and government decide on the routes, and they are more or less fixed. We can supply weather data to latitudes of 85

degrees north and south in SPOS, but actually, the market does not usually want anything farther north than the north of Norway, or sometimes Hudson Bay or the Bering Sea. The behavior of ice is very hard to incorporate into models too; local authorities, such as port authorities and pilot agencies, have much better information about the current situation and the condition of the passages."

To learn more about route optimization enabled by the expertise of master mariners, click here

This content is sponsored by DTN. 

The opinions expressed herein are the author's and not necessarily those of The Maritime Executive.