Specific fuel oil consumption (SFOC)

What SFOC is

Specific fuel oil consumption (SFOC) is the mass of fuel a marine engine burns to produce one kilowatt-hour of brake power, measured in grams per kilowatt-hour (g/kWh). It is the marine term for what other fields call brake-specific fuel consumption (BSFC). A lower number means a more efficient engine, and SFOC is the figure on which engine guarantees, fuel budgets and the EEXI and CII indices all turn.

The “brake” qualifier matters: SFOC is referenced to shaft power measured at the engine coupling, after the friction of bearings and valve gear but before any gearbox or shaft loss, not to the indicated power developed inside the cylinder. The ratio is simply the fuel mass flow divided by that brake power:

The distinction between brake power and indicated power is the engine’s own mechanical efficiency. Indicated power is the work done on the piston by the gas, read from the cylinder pressure trace; brake power is what survives the friction of bearings, rings and valve gear to reach the coupling. The ratio of the two, the mechanical efficiency, runs around 88 to 92 percent on a large two-stroke at full load and falls at part load as friction becomes a larger share of a smaller output. Because SFOC is referenced to brake power, it already carries that friction loss; an indicated specific fuel consumption would be lower, but it is the brake figure that bills the fuel and drives the guarantees.

North American and older records sometimes use the imperial form, pounds per horsepower-hour, where 1 lb/hp·h is about 608 g/kWh, so a two-stroke at 170 g/kWh is about 0.28 lb/hp·h. The conversion tools cover both directions: g/kWh to lb/bhp·h and lb/bhp·h to g/kWh. Every IMO instrument and engine shop-test certificate quotes g/kWh.

SFOC and brake thermal efficiency

SFOC is meaningless without the fuel’s energy content, because the same efficiency burns a different mass of a weaker fuel. The link is the brake thermal efficiency, the fraction of fuel energy that becomes shaft work:

with SFOC in g/kWh and the lower heating value (LHV, also called lower calorific value) in MJ/kg; the 3600 converts the kilowatt-hour to 3600 kJ. The lower heating value is used, not the higher, because a diesel engine exhausts at 300 to 400 degrees Celsius and cannot condense the water vapour to recover its latent heat. Engine makers declare SFOC against a reference LHV of 42,700 kJ/kg (42.7 MJ/kg), the conventional value for marine distillate, so that engines can be compared on one basis. A real heavy-fuel grade carries about 40,500 kJ/kg, so a measured SFOC on that fuel is corrected to the reference before it is published.

At 165 g/kWh on the 42.7 MJ/kg reference, efficiency is 3600 / (165 × 42.7), about 51 percent; the best large-bore two-strokes at their optimum reach 52 to 54 percent. The brake thermal efficiency calculator runs this conversion both ways.

History and development

The number has fallen by a factor of nearly two over a century. Early marine diesels of the 1910s and 1920s consumed around 240 to 280 g/kWh; the gains since have come from combustion-chamber geometry, fuel-injection timing, turbocharging and intercooling. The long-stroke designs MAN B&W introduced in the 1980s, raising the stroke-to-bore ratio above three to one, cut friction relative to power and pushed slow-speed SFOC below 200 g/kWh. The decisive step was electronic control: the MAN B&W ME series and the Wärtsilä RT-flex series, both launched in 2001, replaced mechanically timed injection pumps with common-rail systems whose timing could be optimised across the whole load range, worth five to eight g/kWh over their mechanical equivalents and, more importantly, flattening the part-load end of the SFOC curve. Waste-heat recovery in the 2000s and 2010s added a further system-level gain by turning exhaust energy into electrical power that offsets auxiliary load. The regulatory chapter opened with the EEDI in 2013, which put SFOC at the centre of ship design for the first time, and continued with EEXI and CII in 2023.

Reference values by engine type

SFOC varies with engine type, stroke count and technology generation. The figures below are for current Tier II and Tier III production engines, at ISO reference conditions and the 42.7 MJ/kg reference fuel:

The best individual figures sit at the lower edge of these bands. Large-bore MAN B&W G-type and S-type engines and WinGD X-type engines are documented near 155 to 160 g/kWh at part load with optimised tuning, and the best medium-speed four-stroke, the Wärtsilä 31, holds a verified minimum near 165 g/kWh. A slow-speed two-stroke at 50 to 54 percent brake thermal efficiency is the most efficient prime mover in commercial service, ahead of any gas turbine, automotive engine or simple-cycle power plant.

Engine-maker published figures

The certified figures behind those bands come from the engine programmes. On the two-stroke side, MAN B&W large-bore G-type and S-type engines are documented near 155 to 165 g/kWh at part load with optimised tuning and a few grams higher at full power, and the Mark 10 platforms shaved about two g/kWh off their Mark 9 predecessors across the load range. WinGD’s X-type engines sit in the same region, with the X82 family documented near 156 g/kWh at part load with its tuning option and about 165 g/kWh at full rating in diesel mode, falling below that with variable compression ratio. On the four-stroke side the Wärtsilä 31 holds a Guinness-verified minimum of 165 g/kWh, the best of any four-stroke, while the more common Wärtsilä 46-class engines run nearer 177 g/kWh at rated load and genset engines higher again. These are maker-declared values at reference conditions; an individual engine’s contract figure is fixed at its shop test and recorded in the certificate that travels with the ship.

The SFOC-versus-load curve

SFOC traces a shallow U against engine load, with its minimum in the 70 to 85 percent MCR band, the design optimum, and rising at both ends.

Below about 70 percent MCR the curve climbs because heat losses to cooling water and exhaust become a larger share of a smaller power output, turbocharger efficiency falls sharply at part flow and weakens the scavenge-air pressure, and combustion temperatures drop, raising the risk of incomplete combustion and cold corrosion. Electronically controlled engines, the MAN ME series and the WinGD X and X-DF series, use variable injection and exhaust-valve timing to flatten this part-load penalty, but a residual five to fifteen g/kWh penalty at 30 to 50 percent MCR remains, and that is exactly the region a slow-steaming ship works in. The cube law of ship resistance is what makes slow steaming pay despite that penalty: roughly halving speed needs about an eighth of the power, so the large power saving outweighs the higher SFOC. The cube-law fuel calculator and the slow-steaming savings calculator model the trade.

Above 90 percent MCR the curve rises gently as the turbocharger passes its design point and the air-excess ratio falls. The continuous service rating, the power a ship actually holds on the loaded leg, is conventionally set at 75 to 85 percent MCR to sit near the SFOC minimum while leaving a margin for weather and hull fouling. Engine makers publish a load programme giving SFOC at 25, 50, 75, 85, 90 and 100 percent MCR; dividing measured voyage fuel by average shaft power gives an operational SFOC to benchmark against it.

Tuning the curve

The shape of that curve is not fixed; it can be tuned, electronically and without hardware changes, to suit the trade. High-load tuning puts the minimum at full power, for ships that run hard. Part-load tuning lowers SFOC across roughly 50 to 85 percent MCR, worth a few grams per kilowatt-hour in that band at the cost of two or three grams at full power. Low-load tuning shifts the optimum further down, toward 25 to 70 percent MCR, for ships committed to slow steaming, again trading a penalty at the top. The methods carry maker-specific names, engine-process tuning on the MAN G-types, exhaust-gas bypass and variable turbine area on others, but the principle is common: move variable injection and exhaust-valve timing to favour the load the ship actually works at. Makers will fix the SFOC guarantee point anywhere from 50 to 100 percent MCR, which is why the guarantee load must be read alongside the guarantee value.

ISO 3046-1 reference conditions

SFOC is meaningless without the conditions it was measured at, so engine makers certify it against the reference conditions of ISO 3046-1, the performance standard for reciprocating engines, read with ISO 15550 on power determination:

• Ambient (turbocharger inlet) air temperature: 25 degrees Celsius (298 K)
• Barometric pressure: 100 kPa (1,000 mbar)
• Relative humidity: 30 percent
• Charge-air coolant temperature: 25 degrees Celsius
• Reference fuel lower calorific value: 42,700 kJ/kg

A measurement taken away from these conditions is corrected back to them. Ambient air temperature has the largest practical effect, which is why a ship trading in the tropics, with engine-room air well above 25 degrees, shows a higher SFOC than its shop-test figure; the air-temperature sensitivity calculator applies the ISO correction. The standard allows the measured SFOC to exceed the declared value by up to five percent at high load without breaching the guarantee, widening to about six percent at 65 to 84 percent load and seven percent at 50 to 64 percent. Purchase contracts usually tighten the tested figure to within three to five percent with liquidated damages for exceedance.

SFOC in EEXI, EEDI and CII

SFOC moved from an engineering metric to a regulated one when the MARPOL Annex VI energy-efficiency regime put it inside the numerator of the design and operational indices. In the Energy Efficiency Existing Ship Index (EEXI) and the Energy Efficiency Design Index (EEDI), the CO2 term for each engine is its power multiplied by its SFC multiplied by the fuel’s carbon factor:

A lower SFC shrinks the numerator and improves the index directly. EEXI became mandatory for existing ships from 1 January 2023 under MARPOL Annex VI Regulations 23 and 25, introduced by Resolution MEPC.328(76), with the calculation method in MEPC.333(76) and the EEDI guidelines in MEPC.364(79). Where no certified SFC is available from the engine’s NOx technical file, the guidelines apply default values of 190 g/kWh for a diesel main engine and 215 g/kWh for an auxiliary engine, figures set deliberately above good modern practice to reward submitting real test data.

A key point that is often confused: engine power limitation (EPL) and shaft power limitation (ShaPoLi), the common routes to EEXI compliance, cap the power term P, not the SFC. They do not make the engine burn less per kilowatt-hour; they reduce the power on which the index is calculated. Improving the actual SFOC at sea, by tuning, waste-heat recovery or cleaner hull and propeller, is what improves the operational CII, which has applied to ships of 5,000 GT and above since 1 January 2023 and rates a ship A to E against a tightening reference line. Because annual fuel mass is engine hours times power times SFOC, every gram per kilowatt-hour of operational SFOC feeds straight into the CII rating. The EEXI attained calculator, the CII attained calculator and the SFOC-to-CII converter link the engine figure to the ship indices.

CO2 from SFOC: the carbon factor

The mass of CO2 per kilowatt-hour of shaft work is SFOC multiplied by the fuel’s carbon factor Cf, the tonnes of CO2 produced per tonne of fuel burned, defined in MARPOL Annex VI:

A two-stroke at 165 g/kWh on HFO emits 165 × 3.114, about 514 g CO2 per kWh; the same engine on MGO at 165 g/kWh emits 165 × 3.206, about 529 g, a higher carbon intensity at identical efficiency simply because distillate carries more carbon per tonne. That fuel-switch sensitivity matters for EEXI and CII whenever a ship moves between HFO, VLSFO and MGO under the IMO 2020 sulphur cap. The carbon factors for ammonia and hydrogen are zero on a combustion basis, but that is a tank-to-wake figure: their well-to-wake footprint depends on how the fuel was made, which is the point the emerging well-to-wake rules turn on.

Biofuels already break the fixed-factor model. Under the IMO’s interim biofuel guidance, the carbon factor for the bio-fraction of a blend is not a fixed combustion value but is derived from the fuel’s certified well-to-wake greenhouse-gas intensity times its calorific value, so a certified sustainable biofuel can be credited with a far lower effective carbon factor than the fossil fuel it replaces. The same logic exposes the limit of the simple SFOC-times-carbon-factor sum: it counts only what leaves the funnel. A grey ammonia made from natural gas, or a fossil methanol, can show a low or zero combustion carbon factor while carrying heavy upstream emissions that a tank-to-wake calculation never sees. This is the gap the well-to-wake framework is built to close, and it is why fuel choice and engine efficiency are becoming separate questions: the engine’s SFOC governs how much fuel is burned, while the fuel’s lifecycle intensity governs what that burning is worth against the regulation.

Dual-fuel engines and why mass SFOC misleads

A dual-fuel engine running on gas does not report SFOC; it reports two figures. Specific gas consumption (SGC) is the mass of gaseous fuel per kilowatt-hour, and specific pilot oil consumption (SPOC) is the small mass of liquid fuel injected to ignite it. WinGD’s low-pressure X-DF engines run a pilot below one percent of the heat release, around 0.7 to 1.0 g/kWh, while MAN’s high-pressure ME-GI uses about 1.5 percent. The fair efficiency comparison is the combined heat rate, the energy in the gas plus the pilot per kilowatt-hour.

WinGD’s published energy figures show how efficient gas-mode operation has become. The X-DF2.0 family is documented with a brake specific energy consumption around 6,500 to 6,900 kJ/kWh at its best rating, which works out at a brake thermal efficiency of 53 to 55 percent, with specific gas consumption around 130 to 140 g/kWh of LNG and a pilot of well under one gram per kilowatt-hour. Those energy figures, not the mass ones, are what allow a like-for-like comparison with a diesel-mode two-stroke. The combined heat rate, the gas energy plus the pilot energy per kilowatt-hour, is the single number that captures gas-mode efficiency, and on that basis the best dual-fuel two-strokes match or edge their diesel-only equivalents.

The deeper problem is that mass-based SFOC breaks down as a cross-fuel comparison, because the lighter alternative fuels carry far less energy per kilogram:

Every row in that table is at the same 50 percent efficiency: the methanol and ammonia figures are roughly double not because those engines are inefficient but because the fuel is energy-light. Reading a 360 g/kWh methanol SFOC as “twice as thirsty” as a 170 g/kWh diesel is simply wrong. The honest comparator is the brake specific energy consumption in kJ/kWh, or the efficiency itself, and the regulatory metrics are moving the same way, toward energy-based and well-to-wake accounting. The methanol and ammonia fuel articles cover the storage and handling consequences of that doubled mass flow.

Modern engine technology and best-in-class figures

The slow-speed two-stroke remains the efficiency leader, and the current programmes push the optimum-load figure toward 155 g/kWh: MAN B&W G-type engines with low-load engine-process tuning and WinGD X-type engines with their tuning options are documented in that region. WinGD’s published gas-mode energy figures for the X-DF2.0 family imply brake thermal efficiencies above 53 percent at their best rating, although those are maker-declared values rather than independently witnessed tests.

The dual-fuel landscape has moved quickly. MAN’s ME-GI injects gas at high pressure on the diesel cycle with near-zero methane slip, guaranteed at or below 0.2 g/kWh, while its ME-LGIM runs on methanol and its ME-LGIA on ammonia, the first ammonia two-stroke delivered in 2026. WinGD’s low-pressure X-DF runs the Otto cycle on LNG, with its X-DF-M methanol variant type-approved in December 2024 and its X-DF-A ammonia variant type-approved in January 2026. The methanol and ammonia engines target the same energy-basis efficiency as diesel mode, so their high mass SFOC is, again, an energy-density artefact rather than an efficiency loss.

Methane slip belongs in this section but sits outside SFOC. It is the unburned methane that escapes a low-pressure Otto-cycle gas engine, and it is not part of the fuel that did useful work, so it does not appear in SFOC. It matters because methane has a global-warming potential about 28 times CO2, so even one or two grams per kilowatt-hour carries real climate weight. High-pressure ME-GI engines hold slip at or below 0.2 g/kWh; first-generation low-pressure X-DF engines sat around 2 to 2.5 g/kWh, cut to roughly 1 to 1.2 g/kWh with exhaust recirculation, and further with variable compression ratio. MAN withdrew its low-pressure ME-GA engine in November 2024, citing the tightening methane rules under FuelEU Maritime and the EU ETS, while keeping the near-zero-slip ME-GI in production.

Other consumers: boilers, gas turbines and gensets

Not every fuel consumer produces shaft power, so not every one is rated in SFOC. An auxiliary boiler or exhaust-gas economiser delivers heat, not work, so its consumption is expressed per unit of heat raised, around 90 to 95 grams of fuel per kilowatt-hour of thermal energy, a combustion efficiency near 87 to 91 percent. Marine gas turbines do produce shaft power and are rated in g/kWh, but at 230 to 260 g/kWh and 36 to 40 percent thermal efficiency they are far thirstier than a two-stroke diesel of the same output; they are chosen in naval ships, fast ferries and some cruise ships for their power density and rapid response, not their economy. Combined diesel-and-gas and diesel-electric-and-gas arrangements exploit exactly this by using the turbine only for the high-speed dash and reverting to the diesel, near its SFOC optimum, for cruising. Auxiliary gensets, running at constant speed for electrical load, sit at the higher end of the four-stroke band and are estimated through the auxiliary engine load calculator.

NOx Tier III and the SFOC trade-off

Cutting nitrogen oxides and cutting fuel pull against each other, because the engine settings that minimise SFOC, advanced injection and high peak pressure, also raise the combustion temperature that forms NOx. MARPOL Annex VI Regulation 13 sets the limits, and Tier III, roughly an 80 percent cut from Tier I, applies inside designated NOx emission control areas. How a ship meets it decides the fuel penalty:

• Selective catalytic reduction (SCR) treats NOx after the engine with a urea catalyst and lets the engine keep its SFOC-optimal timing. The fuel penalty is small, well under one percent, essentially the cost of exhaust back-pressure, though it adds urea consumption of a few percent of fuel mass. SCR is the dominant Tier III route for large two-strokes.
• Exhaust gas recirculation (EGR) suppresses NOx in the cylinder by recirculating exhaust, but the high recirculation rates needed for full Tier III carry a significant SFOC penalty, around 10 to 17 percent on a two-stroke in full Tier III mode, although optimised low-rate variants used in Tier II add far less.
• Miller timing, early inlet-valve closing, cuts NOx 20 to 30 percent on its own, not enough for Tier III, but combines with mild EGR and two-stage turbocharging to reach the limit with a manageable fuel cost.

For a ship’s carbon rating the implication is direct: switching to EGR-based Tier III worsens CII through higher fuel unless other efficiency gains offset it, while SCR-based Tier III barely moves the SFOC. The selective catalytic reduction article covers the system design.

Fuel quality, ISO 8217:2024 and SFOC

Marine fuel quality is specified by ISO 8217, whose seventh edition was published in May 2024. The 2024 edition restructures the grades into four tables, formalises the very-low-sulphur (VLSFO) category that emerged after the 2020 sulphur cap, adds bio-residual grades, and, for FAME biofuel blends, requires the calorific value to be physically measured rather than estimated. That last change matters for SFOC: a FAME blend carries about ten percent less energy per kilogram than heavy fuel oil, so the same mass SFOC on a bio-blend represents a different real efficiency, and the energy basis is what keeps the comparison honest.

The standard sets physical and chemical limits, viscosity, density, sulphur, the calculated carbon aromaticity index, but does not set a calorific value, so the 42.7 MJ/kg reference for SFOC declaration is unchanged by it. Ignition quality still feeds through: a low cetane index or a high carbon aromaticity index lengthens ignition delay and worsens combustion, nudging SFOC up by a gram or two per kilowatt-hour before any calorific-value correction. The cetane index calculator estimates that ignition quality from density and distillation.

The cetane sensitivity is small but real, roughly 0.05 percent of SFOC per cetane number, so a fuel at cetane 40 against one at cetane 45 burns about a quarter of a percent heavier in otherwise identical conditions. For residual fuels, which cannot be cetane-rated directly, the calculated carbon aromaticity index stands in: a value above about 850 signals poor ignition and combustion, higher SFOC and more exhaust smoke. The viscosity at the engine inlet is the operational lever, held by the fuel heater within the maker’s window, typically about 12 to 18 centistokes for heavy fuel, so the fuel atomises and burns cleanly. Switching from a high-cetane distillate to a paraffinic very-low-sulphur blend can move SFOC by one to two g/kWh on ignition quality alone, before any correction for the difference in calorific value.

The shift to well-to-wake accounting

The SFOC-and-carbon-factor picture is a tank-to-wake one: it counts the CO2 from burning the fuel on board and nothing upstream. The regulatory frame is moving beyond it. The IMO Net-Zero Framework, approved in outline at MEPC 83 in April 2025, would set a well-to-wake greenhouse-gas fuel-intensity standard measured in grams of CO2-equivalent per megajoule, against a 2008 baseline of 93.3, backed by a pricing mechanism. As of mid-2026 it is approved but not adopted, after the October 2025 session adjourned without agreement, with the earliest entry into force around 2028. The direction is clear even if the timing is not: the metric is shifting from the mass of fuel burned to the lifecycle carbon of each megajoule of energy, which rewards genuinely low-carbon fuels and exposes the upstream emissions that a tank-to-wake SFOC figure hides. For an engine, SFOC stays the near-term handle on CII compliance; for fuel choice, the lifecycle intensity is what will count.

Measuring SFOC

A new engine’s SFOC is fixed at the maker’s test bed. Fuel mass flow is measured by a Coriolis meter, which reads mass directly without a density correction, or by a gravimetric tank on a load cell; brake power is read from a dynamometer. ISO 3046-1 caps the fuel-flow uncertainty at half a percent and the power uncertainty at one percent, for a combined SFOC uncertainty near 1.1 percent. The result is corrected to reference conditions and recorded in the engine’s certified SFOC table, which follows the ship for life.

At sea trials, shaft power comes from a torsion meter on the propeller shaft and fuel mass from a Coriolis meter in the supply line; a clean hull and a contract-tuned engine should bring the sea-trial figure within two to three percent of the corrected shop test. In service, class performance notations require continuous shaft-power and fuel-flow metering, calibrated annually, and the same data feed the IMO Data Collection System and the EU MRV reports. Dividing reported voyage fuel by average shaft power gives an operational SFOC that, compared with the design figure, reveals fouling, wear and the need for maintenance.

The major class societies, DNV, Lloyd’s Register, ABS, Bureau Veritas and ClassNK, offer performance-monitoring notations built on this metering. They require shaft power and fuel flow to be measured continuously to a stated accuracy, the meters to be calibrated by a surveyor, and the data to be aggregated for trend analysis. The commercial value is independent verification: a notation gives a charterer an audited basis for a bunker-consumption claim and an owner a defence against an unfounded one, which is why these notations increasingly appear as a requirement in time-charter recaps alongside the consumption warranty.

Managing operational SFOC

The engine’s certified curve is a ceiling; the SFOC a ship actually achieves depends on how it is run. Tuning moves the minimum of the curve: high-load tuning favours full power, part-load and low-load tuning shift the optimum down toward slow-steaming loads, all through control parameters rather than hardware. Turbocharger cut-out, blanking one of several turbochargers at low load, restores scavenge pressure and can save four to six g/kWh in the slow-steaming band. Derating, formally lowering the rated MCR to match a reduced service speed, keeps the engine near its optimum and avoids the cold-corrosion risk of running a full-rated engine continuously at low load. Waste-heat recovery, taking energy from the exhaust to a power turbine or steam cycle, does not change the main engine’s own SFOC but can cut the ship’s total fuel burn by around nine to eleven percent by offsetting auxiliary load; see the waste heat recovery system article.

Hull and propeller condition act through the load point rather than the curve: fouling raises the power needed for a given speed and pushes the engine off its optimum, so hull cleaning and propeller polishing help fuel by restoring the design load. Keeping the fuel heated to the right viscosity at the engine inlet, managing turbocharger fouling with regular washing, and routing to avoid the heavy weather that forces power reductions all hold the engine nearer its best SFOC. The voyage fuel and CO2 estimator ties these into a whole-voyage figure.

There is a floor to how far a ship should slow-steam on the original engine rating. Below about 20 to 25 percent MCR, cylinder-liner temperatures fall enough for sulphuric acid from the fuel sulphur to condense on the liner wall and cause cold corrosion, and the cylinder oil’s base number has to be matched to the fuel sulphur and the liner temperature to neutralise it. Running a full-rated engine continuously at very low load also sits it permanently off its SFOC optimum. The principled answer for a ship committed to low speed is to derate the engine, formally lowering the rated MCR and rematching the propeller, so that the new full rating aligns with the intended operating band and the SFOC curve and the cold-corrosion margin are both preserved. Derating is a class-approved change recorded against the engine’s certificate.

SFOC in charterparty warranties

In a time charter, the owner warrants a speed and a fuel consumption in defined good weather, and that consumption is an SFOC figure at the contracted service speed, close to the continuous service rating. Disagreement over warranted against actual consumption is a routine source of performance claims, sharpened when the ship runs on a different fuel grade than the shop test used, since the calorific-value correction shifts the mass figure. The arrival of the EU MRV and IMO DCS datasets has changed the evidence base, because both provide independently verified voyage fuel that can be set against the warranty.

Limitations

The figures here are representative of current production engines at reference conditions; an individual engine’s certified SFOC table is the authority for that engine, and real in-service SFOC sits above the shop-test value through ambient conditions, fuel quality, fouling and wear. The reference calorific value of 42,700 kJ/kg is a comparison benchmark, not the energy content of any particular bunker delivered, and mass-based SFOC should never be compared across fuels of different calorific value without converting to an energy basis. Regulatory figures move: the EEXI and CII provisions cited are current through mid-2026, default SFC values and carbon factors are set in the MARPOL Annex VI guidelines and revised periodically, and the Net-Zero Framework that would shift the metric to well-to-wake intensity is approved but not yet adopted. A live efficiency or compliance calculation should be run against the engine’s own data and the current text of the regulation.

See also

Calculators

• Brake thermal efficiency from SFOC
• SFOC air-temperature sensitivity (ISO 3046)
• SFOC-to-CII converter
• Engine thermal efficiency
• Brake mean effective pressure (BMEP)
• Cube-law fuel scaling
• Slow-steaming savings per voyage
• Voyage fuel and CO2 estimator
• Auxiliary engine load
• EEXI attained
• CII attained
• CO2 per kWh from SFOC
• CO2 from fuel (Cf)
• g/kWh to lb/bhp·h

Related wiki articles

• What is EEXI?
• What is CII?
• MARPOL Annex VI
• Marine diesel engine
• Waste heat recovery system
• Selective catalytic reduction
• LNG as marine fuel
• Methanol as marine fuel
• Ammonia as marine fuel
• Heavy fuel oil
• IMO 2020 sulphur cap
• Slow steaming
• Time charter party