Why play with toys? Use the engine rated for abuse.

Marinediesel’s VGT Series of engines is the most powerful, most compact series of engines in its class. Unlike the engines made by our competitors, the VGT Series is designed to withstand the abuse government and commercial operations demand.

These are no mere “toys” designed for powering recreational boats.

Our engines are engineered for long life, low weight, and continuous operations. Engines for pleasure boats may be used 50, or 100, hours per year. The average Marinediesel customer uses their engines over 1,000 hours per year.


In extreme conditions.

In situations where every second standing still COSTS MONEY.

In situations where engine failure COSTS LIVES.

How much can it cost? What is an hour of vessel downtime worth to you? €100? €1,000?

So, why trust your business, or your mission, to power that was designed for light use? You should not. Any savings realized through small differences in purchase price can be quickly lost from a single incident or a single failure.

Only Marinediesel can meet your requirements for performance, reliability, ease of maintenance, and long life. Only Marinediesel is rated to your mission on a bespoke basis. Only Marinediesel can deliver success.



Use it, or lose it


Time is not your friend when it comes to marine diesel engines. Diesel engines, by their nature, operate best when they are started frequently, and operated at WOT (wide open throttle) every once in a while. In a way, this is counter-intuitive, since diesels are often discussed in terms of life cycle, how long they will last before overhaul, and sheer number of hour used. However, a long time between overhauls does not mean much if the engines simply sit in storage or if the vessel spends most of its’ time tied up at a dock.

Diesel engines are complex pieces of machinery. Routine starting and operation keeps internal components lubed up and free from rust or deposits. Additionally, seals and gaskets take time to properly seal, and operating the engine makes good, tight seals. Additionally, diesel fuel degrades and becomes contaminated over time. Routinely starting and operating the engine keeps the fuel fresh, and fuel lines clear with periodic fuel flow. This is why MarineDiesel has a very specific winter storage procedure for owners to follow.

Commercial and government vessels typically have very heavy, continual use. Indeed, we have seen some of these vessel types operate up to 3,000 hours or more per year, under the harshest of conditions.

The problems associated with non-use are typically experienced on recreational, or pleasure, boats. They simply do not get the high use that commercial vessels. (Sometimes as little as 50 hours use per year). This is why it is important that pleasure boat owners start their engines, minimally, at least monthly, letting them run at WOT at least for a little while. If this procedure is followed, the engines should last as specified by their rating, giving years of reliable use.



How long will an engine last?


How long will an engine last?

This is a fair question, and one which can be fairly difficult to answer given the number of variables involved. Some of the factors that influence engine life include:

Type of engine. Is the engine marine or industrial? Industrial, or on-road engines have a much longer life span than marine engines. Why? Several reasons: Better efficiency of cooling; Less variation in RPM; Typically, much lower resistance (water gives much more resistance than friction from four small tires, in addition to vessels being subject to wind resistance also); Fewer devices that can “go wrong” or break (particularly with the cooling system); Typically higher quality and more consistent quality fuel; Much, much less environmental stress, such as corrosion.

Use. Marine engines typically use higher throttle with more variation than engines used on land. Engines used as gensets, in particular, with a low, continuous RPM tend to last a very long time.

Maintenance. Maintenance performed according to the manual’s maintenance schedule have a significantly longer lifespan and service life.

Environment. The marine environment is harsh. Salt air, corrosion, rust, and contact with water all reduce engine life cycle.

In general, using our Marinediesel 6.6L engine as an example, customers can generally expect to receive a service life from their engines:

Marine: 10,000 to 15,000 hours.

Land: Approximately 1,000,000 km.

Genset: Approximately 80,000 hours.





The relationship between engine load and life cycle


When we are selling a diesel engine, sometimes we are not asked for our input as to whether or not we believe an engine is the right choice for a project. A potential customer will contact our distributor or MarineDiesel directly and say, “give me 2 X VGT500 engines, bobtail”. When this happens, we always ask, “How will the engine be used?” The reason why is that we do not want an unhappy end user. Unreasonable expectations usually lead to disappointment.

Our engines are designed with specific applications in mind. They are intended to be used in specific ways, and rated as such. A big part of the rating, and all of the fine print on our promotional material, is defining the word “continuous” use, since every manufacturer interprets that definition in a different manner. In other words, we say continuous means one thing. Yanmar says another. Volvo Penta says another. And so on…

Our engines are designed to provide a specific life cycle and MTBO, under certain use. So, what will happen if we say 80% throttle at no more than 8 hours per day, and the engine is operated WOT (wide open throttle), for 16 hours in a single day? Simple. The load is too high. The engine will not last as long.

What would happen if the naval architect based his calculations on a specific vessel displacement at sea trial, say, 10 tons, and the vessel operated brilliantly at trial. The owner then adds an extra ton of weight (Could be anything. On recreational boats, adding fishing equipment and galley equipment is common. On military boats, extra ammunition is common, and heavy). What happens? The engine becomes overloaded. Either performance suffers, or the engine will not last as long.

How the vessel is operated can also impact engine load and life cycle. Operating the vessel at the wrong trim can increase resistance on the hull, and, consequently, the load on the engine.

A final example could be after sale modifications to the engine or vessel systems. Exhaust and fuel systems see this scenario frequently. Add an extra silencer that is improperly sized, and you have load issues. Extra fuel filtration or metering can also impact engine load. Change a propeller to a different type in order to get a little more speed? That may, in fact, work, but you may also be increasing the load on the engine at the same time.

In many cases, we will receive a maintenance problem that, on the surface, could be regarded as a warranty issue. “Hey, you guys said that my engine would last 3,000 hours, and I need to rebuild at 500! What gives?” However, after looking at the situation, load or other modifications are usually the underlying culprit behind reduced engine life.

It is important to realize that, when looking at vessel and engine performance, there is always a balance between the load and the life cycle. If one performance criterion increases, something else must decrease. It is a question of balance, and a question that is often overlooked.





Maintenance Tip of the Week – Hoses 03/02/2015


Maintenance Tip of the Week – Hoses

The hoses on your cooling system have a life span of approximately three years, after which they need to be changed. Their material can degrade over time in the marine environment, and a burst hose can quickly lead to severe engine damage.


670,000 Liters



670,000 Liters.

That equals:

  1. 3/10 of the volume of a hot air balloon.
  2. 1/4 of the volume of a standard Olympic sized swimming pool.
  3. 1/10 of the volume of the Goodyear Blimp
  4. 60 times the volume of the capacity of a cement mixer truck
  5. The amount of fuel that a MarineDiesel VGT350 engine will consume over its’ total lifespan.

This gives some important room for thought.

At diesel fuel prices of €1.20 / liter in Europe, this equals an expense of  €804,000 in fuel over that engine’s life cycle. When Future Value is taken into account, that cost balloons to over €1,128,000.

Fuel is the biggest operational expense of any engine. More than maintenance. More than spare parts. More than labor.

This is why fuel efficiency is so important when choosing an engine.

This is why many of the articles on this site highlight the engine power and torque curves. The VGT Series produces power curves that are very flat. That means that there is a much bigger RPM range available to reach a required power level. This then means:

The VGT Series of engines has a much lower cruising speed than competing engines. Lower cruising speed means lower fuel consumption.

Lower fuel consumption means bigger bottom line.






Marine Maintenance and Diesel Engines



Maintenance of diesel engines is directly tied to life cycle and reliability. Modern marine engines are proven to perform well over long periods of time, provided that regular routine maintenance is performed.

One factor that is often neglected is the harshness of the marine environment. Salt is corrosive. Humidity causes corrosion. Fuel quality can vary greatly from one place to another. These issues help explain why most marine diesel engines have a much shorter time between overhauls than a similar engine that is installed on a truck or other type of vehicle.

Engine ratings also have a bearing in longevity. Engines that are rated for recreational use, for instance, are designed to be used in a recreational application. Use one of these engines in a heavy commercial setting, and problems are certain to ensue. Maintenance costs will certainly multiply exponentially. At MarineDiesel, we see this situation quite frequently. A potential customer will ask us for a quote on a commercial vessel, but they choose a cheaper engine that was rated for recreational use. Will the engine function? Certainly. Will the boat explode? Certainly not. However, the maintenance expense will be much higher, the life cycle will be much shorter, and the vessel performance will be lacking.

Is it still a good deal…?

All engines require periodic maintenance. As a manufacturer, we are in the “Front Lines” regarding maintenance issues. We see patterns as to what issues occur, not only in our engines, but in engines manufactured by competitors. The three most common maintenance issues that we see are often avoidable, and if diligently monitored, can greatly extend the service life of a marine engine (of any brand):

  1. Fuel quality: The number one (by far) problem we see is the use of bad fuel and neglected filter and polishing.
  2. Exhaust temperature: This is probably the number two issue. The biggest leading indicator of required maintenance.
  3. Smoke: Smoke tells you a lot, from a diagnostic perspective. It is nearly always an indication of required maintenance.

Though a bit of a cliche, engineers often state over and over again, “Read the manual”. The maintenance schedules we develop and publish are based on extensive testing results and are updated based on customer feedback, experiences, and warranty returns. In other words, the schedules are not simply made up out of thin air. If we recommend filter changes every 100 hours, there is absolutely a reason.

Bottom line: If maintenance and service schedules are followed, your engine will give you a far longer service life, and cost you far less money over the long term.



Best of 2014 – Life Cycle Cost calculator



We wish all MarineDiesel customers a happy holiday season. Our factory will close from December 22 through January 5. For the balance of the year, we will be re-running our most popular articles from 2014, based on the number of visitors. We will start new daily articles in the New Year. We hope that you continue to find them interesting.

At MarineDiesel, we often come across potential customer who are confused about which engine to purchase. Yes, there are brand loyalties at play in any power decision, yet, more often than not, cost and price usually plays the biggest part in purchasing decisions, often eclipsing performance or technical requirements.

However, when choosing between two engines, much more goes into the cost calculation than simply purchase price.

Yes, very inexpensive engines are available in the market, usually, but not always, produced in China. Though these engines may be cheaper to purchase outright, their real cost becomes evident when maintenance, service life, and fuel consumption are taken into account.

When choosing an engine, you need to look at the following factors:

Purchase price

Engine rating

Life Cycle

Time between overhauls

Time between service

Fuel consumption

Cost of engine downtime

Cost of spares

Cost of service / labor

All of these factors add to the real cost of an engine, and in comparing one engine to another.

Therefore, in order to make your purchasing decision easier (Whether you choose us, or not), we have made the calculator below available for download for your use, free of charge.

Simply fill in the blanks indicated by yellow, and your real cost is indicated at the bottom. The spreadsheet is pre-loaded with the data from our VGT Series.

We hope you find it useful and helpful in making engine comparisons.

Life Cycle Cost Calculator



Daily Mechanical Checks are Important!



When you are purchasing an engine, it can often seem like the manufacturer may be loading their sales pitch with double-talk regarding engine reliability, and how long your engine will last.

Though it may seem deceptive, there is quite a bit of uncertainty when reliability is discussed. How is the engine used? How much load? How frequently will it be used?  Are spare parts available? These criteria don’t just apply to MarineDiesel’s products. They apply to ANY engine made by ANY manufacturer.

As a manufacturer, we see just about all possible engine states that result from just about all maintenance procedures, vessel missions or jobs, and different geographical locations and conditions. One thing, however, is certain: Performing maintenance inspections and checks on a daily basis will help your engine last the longest possible time and give the most reliable service life, regardless of make or model.

So, for further reference, not our recommended daily maintenance checks for our engines. Most are not complicated and cost little in time or money, but the identification of problems before they occur is critical to a long engine life span.

Daily mechanical checks


General inspection of engine space, look for traces of oil, fuel or water leaks and investigate if any apparent. Check engine bilges for any loose components or debris. Visual check of engines and drive line for any abnormalities.


Main engine pre start checks –  ignore items that are not applicable


Ensure fuel valves and sea water valves are turned on.

Visual inspection of sea water strainer, clean if excessive debris apparent.

Check coolant level that should at least cover the tube nest in the heat exchanger.

Check engine and gearbox oil levels, both must be between the minimum and maximum marks on the dipstick, check for any obvious abnormalities in the oil.

Check power steering oil level, the hot and cold level marks are clearly marked.

Check fuel pre filter bowls, drain down if signs of water or debris is apparent.

Visual inspection of drive belt and check tensioner indicators, check for excessive belt dust and debris.

Visual inspection of air filter.

Check trim system oil level.

Ensure gearbox or drives are in neutral and trimmed down.

Ensure throttle is at idle.

Rotate the gearbox drive shaft and move back and forth to check for any roughness or free play, this should be done regularly as a comparison to detect any developing problems.

Check the water around the drives for signs of any oil.


Run up engines individually and check the following


Check for normal raw water flow through strainer and out of exhaust.

Listen for any abnormal noises.

Ensure engines are up to normal operating temperature before full load or full throttle is applied.


Shutting down procedure


After cruising allow the engines temperatures to stabilise and run on low load or idle for 5 minutes or so before shutting down. It is also recommended to run the engine space blowers after the engines have been shut down particularly in high ambient temperatures.


Genset checks (if fitted)


Check all levels, check condition of drive belts, check for any signs of water oil or fuel leaks. Run up and check sea water flow.





Engine Comparisons: VGT500



This week, we will be highlighting several of our engine models and be comparing them with others that are in the market. Our engines stand on their own merits. All data on other engines is available online. Comparisons are based on closest models / ratings for each manufacturer.

We start with our flagship product: The MarineDiesel VGT 500. Using the Duramax 6.6L as a base, we have created the lightest, smallest, and most powerful marine engine in the market today. Ideally suited for small, very fast craft, the VGT 500 delivers the high performance standards that simply leave other engines lacking.

Figures are based on commercial rating, when possible (Some manufacturers only have one rating, others have multiple ratings.)

Some specifications:

Engine Comparison MarineDiesel Volvo Cummins Yanmar Iveco / FPT
Engine Model VGT500 D6 435 QSB 5.9 6LY3-ETP N67 560
Retail Price (Manufacturer’s Suggested Retail Price, online. Prices may vary significantly. Add’l discounts may be avail) € 41,552 € 57,976 € 44,144 € 41,905 €40,929* (UK Only, Sale Price)
BHP 500 435 472 480 500
kW 373 320 352 353 368
RPM 3600 3500 3400 3300 3000
Cyl 8 6 6 6 6
Displacement (l) 6.6 5.5 5.9 5.8 6.7
Bore / Stroke (mm) 103/98 103/110 102/120 106/110 104/132
Maximum Torque Nm 1130 1040 1278 1280 1500
Time Between Overhaul (hours) 2500 1000 2000 1000 1500
Time Between Maintenance (hours) 100 50 75 50 100
Dry Weight 510 699 612 640 650
Fuel Cons at Top Speed g/kWh 230 208 232 228 215.5
Power / Weight kW/kg 0.73 0.46 0.58 0.55 0.57
Euros per kW € 111.40 € 181.18 € 125.41 € 118.71 € 111.22
Overhaul Cost (60% of New) € 24,931.20 € 34,785.60 € 26,486.40 € 25,143.00 € 24,557.40
Cost at 10,000 hours (Purchase, Overhauls, and Maintenance) € 141,279 € 405,836 € 176,579 € 293,339 € 204,647
Fuel Cost at 10,000 hours, Fuel EUR 0.80 / Litre (Calculated at 435 hp) € 710,476 € 633,905 €733,728 € 696,830 €656,761
Total Cost of Ownership 10,000 hours € 851,755 € 1,039,741 € 910,310 € 990,169 € 861,408

So, engine weights are listed in the table above. What about engine size?

(L) X (W) X (H), in mm

MarineDiesel VGT 500: 779 X 825 X 973 (Note: MarineDiesel engines always allow for remote location of some components, such as the grid cooler, filters, or starter motor. Dimensions, particularly height, can often be reduced considerably or shifted around to a great extent.)

Volvo Penta D6 435: 1,456 X 753 X 897

Cummins QSB 5.9: 1,255 X 836 X 858

Yanmar 6LY3 – ETP: 1,458 X 801 X 793

FPT N67 560: 1,063 X 843 X 766



When comparing power, and especially torque, curves, you need to keep in mind how the vessel will be used. All engine manufacturers rate their engines differently, many times with several different ratings under a single model. Others, like MarineDiesel, can change the ECU and engine programming to suit a vessel’s mission. The curves below are the most common ratings, but when reviewing, attention must be given that these curves can be different or altered due to rating.

MarineDiesel VGT 500:

Volvo Penta D6 435:

d6 pwr torque

Cummins QSB 5.9 472:

qsb power torque

Yanmar 6LY3-ETP:

yanmar 6ly3etp curves

FPT N67 560:

n67 560 curves