Caterpillar Marine: Corporate History

Caterpillar Marine is the marine engine business of Caterpillar Inc., the construction and mining equipment maker incorporated in 1925 at Peoria, Illinois. It sells two distinct engine populations under one brand: Cat high-speed diesels (the 3500 series and the C-series, from the C7 up to the C280) for tugs, fishing vessels, yachts, and gensets, and the medium-speed four-stroke M-series (M20, M25, M32, M43, and the VM43) that came into the company with the 1997 acquisition of MaK Maschinenbau Kiel. The split matters because it determines which vessel a given Cat engine belongs in, and it separates the two engineering centers, Lafayette in Indiana for high-speed and Rostock in Germany for medium-speed. For the dependent calculations that pair with this article, see the marine engine makers directory and the per-engine MCR tools linked below.

This is a corporate and product history. It traces where each engine family came from, how the MaK purchase reshaped the portfolio, and how Caterpillar handles the NOx Tier III requirement that governs every new marine engine on a regulated voyage today. It does not repeat the cylinder-by-cylinder data tables that live on the dedicated Caterpillar 3500 marine engine and Caterpillar C280 marine engine pages; it links to them where the detail belongs there.

Caterpillar Inc.: founding lineage

Caterpillar Inc. was formed in 1925 by merging two California track-type tractor builders, the Holt Manufacturing Company and the C.L. Best Tractor Co. Holt had used the “Caterpillar” trademark since 1910 to describe the crawler track its tractors ran on; Benjamin Holt had demonstrated a working track-laying machine in 1904 at Stockton, California. The merged company kept that name & moved its headquarters to Peoria, Illinois, where the corporate base stayed for decades before the 2017 relocation of the head office to the Chicago area.

The merger settled a patent and market fight between the two firms rather than starting a new product. Both made crawler tractors; Best brought the larger, more modern factory at San Leandro, and Holt brought the trademark and the East Peoria works. By the late 1920s the combined company had standardized on a smaller tractor range and was selling diesel-powered crawlers. Caterpillar built its first diesel engine, the D9900, in 1931, and that decision set the firm on a path toward an engine business that would later run well beyond its own machines.

The diesel program grew through two channels. Cat engines powered Cat machines, and Cat sold engines on their own to other equipment builders, gensets, locomotives, and boats. The marine line is one branch of that second channel. It is worth being exact here: a Cat marine engine is a marinized version of an engine family that also serves on land, with the 3500 and the C-series sharing core architecture across truck, industrial, generator, and marine duty. That shared parentage is the reason the dealer-and-parts network described later in this article reaches as far as it does.

Marinizing a land engine is not a trivial badge change. It means a closed-loop cooling system with a seawater-cooled heat exchanger or keel cooler in place of a road radiator, a marine-grade exhaust with water injection or dry insulation, a reverse-reduction gear or a generator coupling in place of a road transmission, corrosion protection against a salt environment, and a certification path through a classification society rather than an on-highway emissions agency. The core block, the bore and stroke, the crankshaft, and much of the combustion system carry across; the marine package around them is purpose-built. This is why a Cat marine engine shares parts with its industrial siblings yet is a distinct certified product, and why the same dealer can stock the common parts for both.

The corporate structure behind the marine engines is also worth setting out, because the brand spans more than one division. The high-speed engines come from Caterpillar’s own engine operations. The medium-speed M-series comes from the MaK side acquired in 1997. The C280 comes from Progress Rail and the Electro-Motive Diesel locomotive business that Caterpillar bought in 2010. All three sell under the Cat Marine name today, but they trace to three separate origins, and that origin map is the single most useful thing to keep in mind when reading the product line.

How Caterpillar entered marine

Caterpillar’s move into boats was incremental and ran through the mid-twentieth century. Fishing fleets, harbor craft, and military auxiliaries took marinized versions of the company’s truck and industrial engines as those families matured. There was no single launch date for “Cat Marine” as a product; the brand grew out of demand from operators who already ran Cat equipment on land and wanted the same parts counter to cover the boat at the dock.

The change of footing came with the 3500 series in the late 1970s. The 3500 was the first Caterpillar engine family designed with marine duty as a primary target rather than an adaptation, and it remains the company’s central commercial-marine product more than four decades later. The 3508, 3512, and 3516 (the trailing digit gives the cylinder count, 8, 12, 16) cover roughly 600 to 2,700 kilowatts in marine ratings. The line is high-speed by the conventional cut, running at 1,600 to 1,925 revolutions per minute in most marine ratings; for the speed-class definition that puts it on the high side of the line, see high-speed four-stroke marine engines. The 3512C variant is common enough in towboats and offshore supply vessels that it has its own per-cylinder MCR calculator.

Through the 1980s and 1990s the 3500 made Cat a major name in tugs, supply boats, fishing vessels, and the broad workboat market, with the strongest position in the Americas. The reason was structural, not just commercial: the dealer service network gave Cat a regional parts-and-labor footprint that European and Japanese builders could not match outside their home regions. A boat owner in the Gulf of Mexico or on the inland river system could get a 3500 part and a technician faster from a Cat dealer than from almost any competitor, and that advantage compounds over a 30-year hull life.

The 3500 itself has been through several generations. The original engine gave way to the 3500B and then the 3500C and 3500E ratings, each tightening fuel consumption and lifting the rating ceiling while staying within the same basic block dimensions. The C-generation engines added higher-pressure fuel systems and electronic control, which is what let Caterpillar push the same architecture up toward the C175’s range and keep the 3500 competitive against newer clean-sheet designs. An operator looking at a 3508, 3512, or 3516 today is looking at an engine whose layout is decades old but whose injection, control, and aftertreatment are current, which is part of why the family has stayed in production so long.

The duty cycle a 3500 sees is a large part of its design brief, and it differs sharply from a merchant main engine. A harbor tug spends much of its day at idle or low load with short, hard bursts of full power during a ship assist; a fishing vessel runs steaming load out to the grounds, then a different load while working gear; an offshore supply vessel cycles between transit and dynamic-positioning standby. A high-speed engine like the 3500 is built for that variable, intermittent duty, with the ability to accept and shed load quickly, rather than for the steady high-load running that suits a medium-speed merchant engine. Matching the engine class to the duty cycle is the first decision in any marine repower, and it is where the high-speed-versus-medium-speed split first bites.

The C-series high-speed engines

The C-series is the modern naming convention that sits across most of the Caterpillar high-speed range. The number after the C is the displacement per cylinder in liters, so a C18 has about 1.8 liters per cylinder & a C32 about 4.1 liters across its V12. The marine C-series runs from the small C7 and C9 up through the C12, C18, and C32, which together cover yachts, fishing vessels, small workboats, and high-speed craft. The C32 is the upper bound of the conventional high-speed Cat marine block and reaches roughly 1,000 to 1,900 kilowatts depending on the rating and duty class.

Above the C32 the naming gets less tidy, and this is where buyers most often get confused. The C175 is a clean-sheet high-speed family, offered in V12, V16, and V20, that extends Cat high-speed output toward 4,000 kilowatts and is used in larger workboats, fast ferries, and naval craft. It is not a member of the 3500 family; it is a separate, later design that overlaps the upper 3500 ratings.

The C280 is a different animal again, and the distinction is the single most important technical point in the whole Caterpillar marine portfolio. The C280 is a medium-speed engine with a 280 millimeter bore and a 300 millimeter stroke, running at 900 or 1,000 revolutions per minute, offered as L6, L8, V12, V16, and V20 from roughly 2,500 to 8,000 kilowatts. It came to Caterpillar from the Electro-Motive Diesel locomotive line that Cat acquired through Progress Rail in 2010, not from MaK and not from the high-speed 3500 lineage.

That EMD heritage is a common source of error, so it is worth stating plainly. EMD (Electro-Motive Diesel) is a locomotive and engine builder with its own long history; Caterpillar’s parent owns the rail business through Progress Rail, and the C280 marine engine descends from an EMD-developed locomotive engine. But “Cat” and “EMD” are not the same brand, and an EMD 710 or 1010 locomotive engine is a separate product line from the C280 marine engine even though they share corporate ownership. Do not treat a reference to EMD as a reference to Caterpillar Marine, and do not treat the C280 as an EMD-branded marine product; it is sold as a Cat engine.

The 1997 MaK acquisition

The decisive expansion of Caterpillar Marine came in 1997, when Caterpillar bought MaK Maschinenbau Kiel, the German medium-speed marine engine builder, from the Krupp side of what became ThyssenKrupp. MaK had been making medium-speed four-stroke marine engines at Kiel since the 1920s and held a strong position in ferries, mega-yachts, naval auxiliaries, offshore vessels, and merchant propulsion in the mid-bore band. The full MaK story has its own page; see MaK Maschinenbau Kiel marine engines.

The purchase gave Caterpillar a complete medium-speed range it did not build itself, sitting above the high-speed 3500 and C-series. Before 1997 a customer who needed a 6,000 or 12,000 kilowatt main engine for a ferry or an offshore construction vessel had to go to MAN, Wärtsilä, or another medium-speed house, because Cat’s largest engine topped out in the high-speed niche. After 1997 Caterpillar could quote the whole job, high-speed gensets and medium-speed main propulsion alike, from one brand & one dealer relationship.

MaK’s engines were rebranded under the Cat Marine name, but the engineering culture and the Kiel base stayed in place. Caterpillar kept Kiel as the design center for medium-speed marine engines and retained the M-series naming that MaK had used, where the number after the M is the cylinder bore in centimeters. The line as it stands runs the M20 (200 millimeter bore), M25, M32, and M43 (430 millimeter bore), with both in-line and V configurations, the largest being the VM43 V-engine. Outputs run from roughly 1,000 kilowatts at the small end of the M20 to about 16,800 kilowatts for the largest VM43 ratings. For the four-stroke speed class these sit in, see medium-speed four-stroke marine engines, and for the working cycle underneath both speed classes, four-stroke marine diesel engine fundamentals.

The acquisition did one more thing that is easy to miss: it gave Caterpillar a builder of true merchant-propulsion engines, not just workboat and genset diesels. A medium-speed engine running at 500 to 1,000 revolutions per minute is built for tens of thousands of hours between major overhauls at high load factor, which is a different design brief from a high-speed engine that spends much of its life at part load in a workboat. The M-series let Cat compete for cargo-ship and ferry main-engine work it had been shut out of before.

MaK’s own history reaches back to the 1920s at Kiel, where the firm built medium-speed engines for the German and export fleets through several ownership eras, including the long stretch inside the Krupp industrial group. By the time Caterpillar bought it, MaK held a recognized name in the offshore, ferry, and luxury-yacht markets, with the M32 and M43 as the engines that carried the marque. Caterpillar’s decision to keep the MaK name in the market for years after the purchase, rather than erasing it immediately, was a recognition that the brand carried trust an owner would pay for. Even now, with the engines sold as Cat, many operators and naval architects still say “MaK” when they mean the medium-speed M-series, the same way buyers said “B&W” for years after that name folded into MAN.

The integration also handed Caterpillar a German engineering and manufacturing base it had not had before, with the design depth that medium-speed four-stroke work demands. Medium-speed engines run higher cylinder pressures and longer continuous duty than high-speed engines, so their bearings, liners, valves, and turbocharging are engineered to a different standard, and the Kiel team carried that knowledge. Keeping the engineering center in Kiel, rather than moving it to the United States, preserved that capability instead of trying to rebuild it from scratch.

How the portfolio is positioned

The clearest way to read the Caterpillar Marine line is by speed class & duty, not by the engine name. Two populations exist, and they almost never compete for the same install.

Cat high-speed (the 3500, the C7 through C32, and the C175) goes into workboats, tugs, fishing vessels, yachts, fast ferries, naval craft, and emergency or harbor-duty gensets. These engines run fast, weigh less per kilowatt, cost less to buy, and are built for the duty cycle of a boat that idles, maneuvers, and runs hard in bursts. They are the volume product and the reason the brand is so widely distributed.

MaK-derived medium-speed (the M20 through VM43, plus the EMD-derived C280) goes into ferry and merchant main propulsion, large offshore and construction vessels, FPSO and floating-power applications, and the bigger genset sets where a high load factor over long running hours rewards the lower fuel consumption and longer overhaul interval of a medium-speed engine. These are the higher-value, lower-volume product, and they put Cat in direct competition with MAN Energy Solutions and Wärtsilä in the mid-bore band.

The competitive map around this split is useful to keep straight. In high-speed, Caterpillar’s nearest rivals are Cummins and the MTU side of Rolls-Royce Power Systems; in medium-speed, the field is MAN and Wärtsilä. A wider survey of who builds what across both speed classes lives in the marine engine makers directory. The persistent gap in Cat’s range is the large-bore two-stroke and large four-stroke band above about 600 millimeter bore, which serves the largest container ships, cruise vessels, and gas carriers; that segment belongs to MAN and Wärtsilä, and Caterpillar does not contest it.

Tier III and NOx compliance

Every new marine diesel engine on a regulated international voyage answers to MARPOL Annex VI Regulation 13, the IMO NOx code. The rule sets three tiers keyed to engine rated speed and the date the ship was built. Tier I and Tier II are global limits that tighten with build date; Tier III is the stringent limit that applies inside designated NOx Emission Control Areas (the North American and US Caribbean ECAs, the North Sea, and the Baltic) for ships built on or after the relevant entry dates. Tier III cuts the NOx limit by roughly 80 percent against Tier I for the same engine speed, and no current marine diesel meets it on combustion tuning alone.

Caterpillar meets Tier III on its medium-speed and larger high-speed engines mainly through selective catalytic reduction, the same aftertreatment approach used across the medium-speed industry. An SCR system injects a urea solution into the exhaust upstream of a catalyst, where the ammonia reduces NOx to nitrogen and water. The technique is mature; the engineering work is in sizing the catalyst, managing the urea dosing across the load range, and keeping exhaust temperature high enough for the reaction. The same chemistry and the same trade-offs apply whether the host is a two-stroke or a four-stroke; the parallel two-stroke case is covered in SCR retrofit on two-stroke engines and Tier III compliant two-stroke engines, and the underlying limit is described under marine auxiliary engines and generators for the genset case.

The exhaust-temperature requirement is the practical catch with SCR, and it shapes how the system is run. The reduction reaction needs the catalyst above roughly 250 to 300 degrees Celsius to work, and below that the urea does not convert cleanly and can deposit as a solid in the catalyst. A high-speed or medium-speed engine at low load runs a cooler exhaust, so at light load the SCR may not be in its working window, which is exactly the load band a maneuvering or standby vessel often sits in. The engineering answer is a combination of catalyst sizing, exhaust-gas bypass, and in some installations a reactor placed close to the turbine outlet where the gas is hottest, plus a control strategy that keeps the engine off the lowest loads when Tier III operation is required inside an ECA.

Tier III applies only inside the designated NOx Emission Control Areas, so a ship trading worldwide carries a dual-mode setup: it runs Tier II outside an ECA, with the SCR on standby, and switches the SCR in as it crosses the ECA boundary. That switching, the urea storage and dosing, and the certificate that proves both modes work are part of the cost and the complexity that Tier III adds to a new build. For the engine maker the work is in delivering an engine-and-aftertreatment package that holds the certificate across the whole operating envelope, not just at the rated point on a test bed.

Tier III is a NOx rule and nothing else. It does not touch carbon dioxide, which is governed by the separate efficiency regime, and it does not touch sulfur, which the 0.50 percent fuel cap handles. A buyer should not assume that an SCR-equipped Tier III engine is a low-carbon engine; the two questions are independent. The carbon side is governed by the EEXI and CII regime; for the existing-ship index that ties an engine’s fuel rate to a ship-level carbon figure, see what is EEXI.

The fuel-and-carbon relationship behind these rules is worth making concrete, because it is what an engineer actually computes. An engine’s specific fuel oil consumption (SFOC, the grams of fuel per kilowatt-hour at the crankshaft) converts directly to a brake thermal efficiency and to a carbon-dioxide figure per unit of work, through the carbon content of the fuel.

A medium-speed M-series engine on heavy fuel oil or marine gas oil at a typical full-load SFOC near 180 grams per kilowatt-hour sits at a brake thermal efficiency a little above 45 percent, which is the headline reason a medium-speed main engine is chosen over a high-speed one for long-haul propulsion. The same SFOC figure, multiplied by the fuel’s carbon factor, gives the carbon dioxide emitted per kilowatt-hour, which is the input to the ship-level carbon indices.

SFOC is not a single number; it shifts with engine load, with charge-air temperature, and with the fuel. A hot-day derate or a high charge-air temperature raises the SFOC and the fuel bill, which is why sea-trial figures are quoted at a reference air temperature and corrected to it. The same engine that reads 180 grams per kilowatt-hour on a 25 degree Celsius reference day will read a few grams worse in a tropical engine room with charge air pushing past 45 degrees Celsius, and an owner comparing two makers has to put both numbers on the same reference basis before the comparison means anything.

A second point about SFOC is that it is not flat across the load range. A medium-speed M-series engine has a fuel-rate trough near 80 to 85 percent load and rises at both ends, so a ferry that runs its mains at 50 percent for most of a crossing pays a fuel penalty against the data-sheet figure. This is one of the reasons the engine count and the load split across a multi-engine plant get as much design attention as the choice of engine model. Running three engines at 70 percent often beats running two at full and one shut, once the part-load fuel curve and the maintenance hours are both counted.

Cat dual-fuel and methanol direction

Caterpillar’s path through the energy transition is staged, and it differs between the two engine populations. On the existing diesel range, the first step is fuel flexibility without new hardware: Caterpillar has certified its marine engines for hydrotreated vegetable oil (HVO) and for blends, a renewable diesel that drops into the existing fuel system. HVO does not change the engine; it changes the carbon accounting of the fuel that goes in, so it is the lowest-friction near-term lever for an operator who wants to cut lifecycle carbon without repowering.

The deeper change is gas and alcohol fuels on the medium-speed M-series, where the larger engine and the lower speed give room for the longer combustion and the harder thermal management that dual-fuel running needs. MaK and Caterpillar have a long history of dual-fuel medium-speed engines that burn natural gas with a diesel pilot for ignition, and the M-series carries that capability forward. The methanol direction follows the wider market: methanol burns in a four-stroke with a pilot fuel and a modified injection system, and it has the practical advantage of being a liquid at ambient conditions, which simplifies bunkering against the cryogenic handling that liquefied gas demands. Caterpillar has signaled methanol-capable medium-speed development in step with the order book, rather than ahead of it.

Two cautions belong here. First, an alternative-fuel engine does not by itself make a ship low-carbon; the carbon depends on how the fuel was produced, and grey methanol from natural gas carries close to the lifecycle carbon of diesel. Second, gas and methanol carry their own emissions issues, methane slip for gas and combustion completeness for methanol, that the engine maker has to manage and that the buyer should ask about specifically rather than accept as solved.

The dealer and aftersales model

The Caterpillar dealer network is the part of the business that competitors find hardest to copy, and it is the main reason a 3500 or a C32 wins an order against a technically similar engine from another house. Caterpillar sells and supports through a network of independent dealers covering most of the world, each holding territory, parts stock, trained technicians, and overhaul capacity. The marine engine rides on the same network that supports Cat’s mining, construction, and power-generation customers, so the parts depot and the service crew that cover the quarry up the road also cover the workboat at the dock.

For an operator with a mixed land-and-sea fleet, common among dredging, construction, offshore, and forestry firms that run both heavy equipment and support vessels, the shared infrastructure is a real operating saving. One parts account, one set of service contracts, and one condition-monitoring platform cover both halves of the fleet. The network also carries the digital service layer, remote monitoring and fleet-management tools that read engine data and schedule maintenance against running hours and load history rather than a fixed calendar.

The aftersales economics are the quiet center of the marine engine business. An engine is bought once and serviced for 25 to 30 years; the parts, the reman components, and the overhaul labor over that life can exceed the original engine price several times over. A dense dealer network captures that aftermarket revenue and locks in the customer, which is why a slightly more expensive engine with a strong local dealer often beats a cheaper engine with thin regional support. The fuel bill over that life dwarfs both purchase and parts, and it scales with how hard the engine is run, so the operating choice of engine load matters as much as the purchase choice of engine model.

Caterpillar’s reman program is part of this. The company runs one of the larger industrial remanufacturing operations of any engine maker, taking worn cores (cylinder heads, turbochargers, fuel injection components, even whole engines) and rebuilding them to a spec the company warrants, then selling them back into the field at a discount to new. For a marine operator this turns a major overhaul into a parts swap rather than a long yard stay, and it keeps an old hull’s engine supported decades after the original build line has moved on to a newer model. The reman channel also feeds the same dealer network, so the parts counter that sells a new 3512 head also sells a reman one.

The condition-monitoring side has grown into its own business. Sensors on the engine feed running data (load, temperatures, vibration, fuel rate) to a fleet-management layer that flags a developing fault before it becomes a failure and schedules maintenance against actual running hours and load history rather than a fixed calendar interval. For a fleet operator the saving is in avoided unplanned downtime, which on a working vessel costs far more than the part itself; a tug off-hire in the middle of a job loses the day rate plus the contract penalty, and either dwarfs a turbocharger.

Manufacturing footprint

Caterpillar builds its marine engines at a small number of plants split by engine type. The high-speed 3500 and the C175 are built principally at Lafayette, Indiana, the company’s large high-speed engine works. The smaller C-series engines are sourced from Caterpillar’s wider industrial and engine plant network, including the Illinois operations. The medium-speed M-series is built in Germany, with Rostock as the main medium-speed marine plant and Kiel retaining the engineering and heritage role from the MaK days. The C280 comes through the Progress Rail and EMD side of the company. Component sourcing for all of these runs through Caterpillar’s global supplier base, the same one that feeds the machine business.

This plant split tracks the corporate history exactly. Lafayette is Caterpillar’s own high-speed line; Kiel and Rostock are the MaK inheritance; the C280 is the EMD inheritance. The brand is one, but the three manufacturing strands have separate roots, and that is the cleanest way to remember which engine came from where.

Where Caterpillar stands

Caterpillar Marine is strong in the broad mid-output band and unmatched in service reach, & it is absent from the largest-bore segment. The 3500 and the C-series give it the widest distribution of any high-speed marine engine brand, and the MaK-derived M-series gives it a real medium-speed presence for ferries, offshore vessels, and mid-size merchant propulsion. The dealer network turns both into a long-life aftermarket business that is hard for rivals to displace once an engine is installed.

The gap is at the top. Caterpillar does not build the large two-stroke main engines that drive the biggest container ships and tankers, nor the largest four-stroke engines for big cruise ships and gas carriers; that ground belongs to MAN Energy Solutions and Wärtsilä. The competitive question for the next decade is whether the fuel transition rewards Cat’s spread and service depth, or whether it concentrates value in the large-bore dual-fuel engines where Cat does not play. Both outcomes are live, and the answer will show up in the order book before it shows up in any forecast.

Limitations

This article is a corporate and product history, not a specification sheet. The output ranges given here (for example, “roughly 600 to 2,700 kilowatts” for the 3500, or “about 16,800 kilowatts” for the largest VM43) are approximate band figures meant to place each family relative to the others; the exact rating for a given engine depends on the rating class, the duty cycle, the speed, and the certification, and must be read from Caterpillar’s current marine engine data sheet for that model and rating, not from this page.

The Tier III description is a summary of how Caterpillar meets the IMO NOx rule in general terms. Whether a specific engine on a specific ship meets Tier III, and by what method, depends on the build date, the engine rated speed, the ECA the ship trades in, and the certificate issued for that engine; verify against the engine’s EIAPP certificate and NOx Technical File, not against this narrative. The same caution applies to the alternative-fuel claims: HVO certification, dual-fuel capability, and methanol readiness vary by engine family and rating, and an operator should confirm the certified fuel for a specific model with Caterpillar before relying on it.

Product lines change. Caterpillar adds, renames, and retires engine ratings on its own schedule, and the brand boundaries between Cat, EMD, and the M-series can shift with reorganizations inside the parent company. The EMD-versus-Cat distinction for the C280, and the MaK-versus-Cat history for the M-series, are accurate as corporate lineage but are not a guide to current marketing names, which Caterpillar sets and revises. For live model availability and the controlling specification, the Caterpillar marine product pages are the authority; this page explains the history and the structure behind them.

See also

• MaK Maschinenbau Kiel marine engines
• Caterpillar 3500 series marine engine
• Caterpillar C280 medium-speed marine engine
• Cummins marine corporate history
• Rolls-Royce Power Systems and MTU corporate history
• High-speed four-stroke marine engines
• Medium-speed four-stroke marine engines
• Four-stroke marine diesel engine fundamentals
• SCR retrofit on two-stroke engines
• Tier III compliant two-stroke engines
• What is EEXI
• Marine auxiliary engines and generators
• Marine engine makers

Related calculators

• Caterpillar 3512C marine: MCR per cylinder
• Caterpillar C32 marine: MCR per cylinder
• Caterpillar C280-16: MCR per cylinder
• System: emergency genset, high-speed diesel
• System: auxiliary engine, medium-speed four-stroke
• Marine engine model decoder