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Bridge in Hong Kong and Container Cargo freight ship

Two Ways to Optimize Fuel Consumption Ahead of IMO 2020

November 08, 2019

From January 1, 2020, the limit for sulphur in fuel oil used onboard ships operating outside designated emission control areas will be reduced from 3.50% m/m to 0.50% m/m (mass by mass). This limit is set in Annex VI of the International Maritime Organization (IMO) International convention for the Prevention of Pollution from Ships (MARPOL).

While predicting the future fuel price is indeed a challenging task, it is widely expected that the transition to a higher-grade fuel will result in substantially higher fuel costs for the industry. Refining makes low-sulfur fuel more expensive—making fuel efficiency even more important than it already is.

IMO 2020 fuel price forecast


Putting aside ongoing concerns on price and availability of compliant fuels, fuel efficiency remains a key driver for the industry. Fuel-efficient vessels will be even more competitive than they are now, while vessels with scrubbers installed may have a significant competitive advantage. It is expected that, initially, vessels with scrubbers will be able to secure premium charter rates. However, if most vessels in a specific segment install scrubbers, daily rates will be lowered. Those vessels that do not have a scrubber may be forced to reduce their rates to unsustainable levels, eventually driving them out of the market. It is therefore crucial for owners to monitor the competition in their segment and find new ways to save fuel to ensure they are not left behind.

A Simple Way to Save Fuel

Research led by the International Association of Maritime Universities stated, “The shortest distance between two points (ports) is not always the fastest due to currents, wave height and winds. When modern systems are integrated with the bridge computers, fuel-efficient routing is possible according to real-time weather routing services. In this way, it is possible to provide fuel economy up to 10%.”

A Fuel Optimization Service (FOS) is specially designed to meet the needs of all involved in the ship owning/chartering chain. The service provides ship operators the tools and services they need to make cost-saving decisions, then quantify and report on those decisions.

Route Analysts can then determine the safest, most efficient route (and recommend speed if a required ETA is provided)—balancing voyage time and fuel consumption. Making this decision prior to sailing is imperative to achieve optimal savings. Therefore, Analysts provide a voyage time and consumption estimate (and total cost when requested) at both the recommended speed to make the required ETA (or the vessel’s stated full C/P speed if no ETA is required) and any alternative eco-speed(s). The charterer receives a pre-voyage report showing the calculated results in terms of time, consumption (and cost if requested), of all considered routes.

The Detriment of Fouling on Fuel Efficiency

Barnacles on ship

Barnacles, an example of fouling, on the hull of a ship.

Fouling, the collection of organisms like barnacles on the hull of ship, is proven to reduce the ship’s performance by up to 40% due to surface drag. According to Thilo Dückert, VP Fleet Performance Management at StormGeo, “Every ship that goes through the water collects algae, shells and other organisms, especially in warm waters. With time, it grows thicker—increasing resistance and worsening the performance (and thus consumption) of a ship.”

Both underwater hull cleaning and dry-docking were found to generate good energy savings, however, there are major differences between the two. Research done by Professor Roar Adland of the Norwegian School of Economics determined that cleaning the ship’s hull at dry-dock can increase overall ship efficiency by up to 17%. If necessary, cleaning the hull underwater in between dry-docking can improve fuel efficiency by up to 9%.

The reason for this efficiency difference is because dry-docking ensures the hull is completely cleaned and re-coated, whereas underwater cleaning can be challenging and lead to a removal of part of the coating. This is detrimental to fuel efficiency, as the coating reduces drag and reduces fouling. Furthermore, underwater hull cleaning cannot always be performed, due to a region's environmental regulations.

Conversely, the benefits of intermediate hull and propeller cleaning (in between dry dock periods) tends to justify its cost. For example, an underwater hull cleaning costs an average $20,000 USD and the propeller an additional $3,500. At 14 knots, a vessel consuming 35 MT/day of HFO in the main engine would spend around $15,000 per day on fuel at a rate of $430/MT of HFO. In this scenario, the hull cleaning pays itself back over a typical 15-day voyage in fuel efficiency gains alone.

Optimizing the Timing of Cleanings

While hull cleaning is critical for maximum fuel efficiency, it is also critical that ship owners time this process in a way that optimally takes ship performance into consideration. Waiting too long between cleanings can add costs from increased fuel consumption, while too-frequent cleanings can be costly over time.

ECO Insight enables ship owners to visually track hull and propeller performance based on a comparison of the measured and ideal power in each weather condition, speed, draft and trim condition. This information enables ship management to identify the best window and plan for hull cleaning according to the vessel’s schedule. This allows the ship manager to predict costs and time while enabling the ship owner to take advantage of all fuel saving opportunities.

Regarding ECO Insight, Dückert adds, “The systems uses an algorithm that also allows ship owners to determine whether the coating works as promised by the manufacturer. As painting is rather expensive, that's an important factor to measure.”

Fuel efficiency is desired by both the owner of the vessel and the party that usually pays for the fuel: the charterer. With IMO 2020 due to take effect in just a few short months, it’s crucial that both parties find ways to increase fuel efficiency, either through weather routing, fleet performance management and/or optimal hull cleanings.