When does outboard power become ridiculous?

Outboard engines have their place and uses. However, a trend over the last few years has been to simply add more outboards to a hull in order to give it more power. No longer are there simply triple or quad outboard installations, but sometimes even five, six or more.

At what point does simply adding more outboards become pointless?

When the costs outweigh the benefits.

The vessel pictured is a pretty well-known photograph of a drug-runner caught in the English Channel (a “scandal” in the UK marine industry at the time). It essentially is engine and fuel tank. Now, most people are not buying boats for smuggling, but are intending to use the vessel over an extended period of time. What does adding extra engines actually do as far as performance?


  1. Added weight (not just the engine, but all equipment, such as mounts and the weight of extra fuel).
  2. Added drag.
  3. Reduced maneuverability.
  4. Reduced safety (often, the hull was not designed for such applications)
  5. Huge increase in fuel costs.
  6. Reduced running time and range (unless larger fuel tanks were designed or installed)
  7. Greatly increased maintenance expense
  8. Difficulty in ventilating the props.



  1. Greater power.
  2. Greater acceleration.


Note that the negatives are pretty big, compared to the positives and their associated costs. Of course, these negatives can be minimized by using diesel inboard engines.

Should a vessel be equipped with two 250 hp outboards, or a single VGT 500? What about instead of three 300 hp Mercury Verados, two VGT 450s?

Unless the vessel has absolutely no room for an inboard, the inboard option will win every time.

  1. Weight: Two Mercury Verados weigh 586 kg. A single VGT 500 weighs 515 kg. Even with gearbox and drive, the weight differential is only around 100 kg.
  2. Drag: Fewer engines mean less drag. All of the time.
  3. Maneuverability: Even numbers are more maneuverable, due to less torsional pull. However, the reduced drag and greater number of propulsion options mean that a single inboard will be as good as or more maneuverable than multiple outboards.
  4. Fuel: No contest. A single diesel VGT will save enough money to pay for the differential in price very, very quickly.
  5. Range: Likewise, the range can be longer, with smaller fuel tanks.
  6. Maintenance: Though an inboard diesel, depending on engine compartment and configuration, is less accessible, it will have a far higher life cycle and require less maintenance and access.
  7. Acceleration: Multiple outboards can accellerate very quickly. But guess what. A Marinediesel VGT engine, designed for high speed craft, will accelerate faster.
  8. Service life: A VGT engine will last as much as five times longer than even the highest quality outboards.

New Product Announcement! VGT Axis Drive


Coming in January, 2016!

V8 500 VGT Turbocharged Diesel Marine Propulsion System “Axis Drive”

Caudwell Marine® Axis Drives are the world’s most technologically advanced marine propulsion system. The 500 VGT Axis Drive, designed for standard 13° transom installations, both available with left or right hand rotation propellers, is packed with innovative features not found in competitive drives.


This range of engines is designed to be as compact and lightweight as possible while maintaining durability and serviceability. They are intended for lightweight and high speed vessels and have a light duty rating.

• The aerodynamically efficient variable geometry turbocharger and the improved high pressure direct fuel injection system allow the 6.6 litre V8 to respond immediately and deliver smooth, consistent power, with a flat torque curve from 1 850 rpm all the way to the red line
• 4 valves per cylinder.

• Common Rail fuel injection.

• Variable geometry turbo.

• Safety warning systems monitor engine coolant temperature and level.

• Raw water flow is also monitored by exhaust temperature sensors.

• The engine’s closed cooling system gives improved corrosion resistance and minimizes the amount of flushing required after use.

• Raw water circulation is controlled by a belt driven rubber impeller pump, ensuring adequate water flow to the intercooler, heat exchanger, engine oil and power steering coolers.

• Both the engine and drive systems are controlled electronically by the NIRA Engine Control Unit (ECU).

• Electronically controlled variable geometry turbo to ensure excellent bottom end torque and performance.

• Gear train noise is minimized though using a CentaFlex Torsional damper system.

• Exhaust noise is reduced via routing exhaust gasses through the propeller hub.

power torque curve

The unique Axis Drive power train design is like a Pod drive mounted on the transom. It eliminates the universal joint as found in traditional stern drives, ensuring that power transfer from crankshaft to propeller is more direct and quiet, with less power loss at the propeller. Most importantly, it allows full power to be applied at all steering angles and trim angles.
The low drag bullet and pick up allow for high speeds.

The turning geometry of the patented integral axial steering system ensures safer high speed turns and exceptional handling characteristics at all speeds.

An electronically actuated dog clutch provides smooth, effortless gear selection controlled by the ECU.

A constant trim speed of 3 degrees per second, irrespective of load and speed. Trim range of -4 degrees to +33 degrees.

Installs using only 6 transom mounting bolts and 2 forward engine mounts, plus plug and play electronics make it the quickest and easiest installation possible

• Through prop exhaust
• Integral Raw Water pick up
• Dual power assisted and direct helm hydraulic steering
• Chrome plated styling covers
• Integrated hall effect sensing for steering and trim angles offering closed loop feedback for digital docking control
• Dry sump main gearbox
• Low drag anti-cavitating lower unit hydrodynamic profile
• Integrated oil temperature and pressure sensing for the gearbox
• Anti – log strike shear protection for the lower unit.
• 64 degree turning arc.

To read more about the Axis Drive, check out our catalogue listing or MD_V8 500 VGT Axisdrive Product Bulletin. Remember, though not available until January, speak with your local Marinediesel distributor today and indicate that you would like to be one of the first to try this new and innovative drive system!

Ski Boat and Parasail Boat Engines


The market for commercial marine engines is quite varied. There are dozens of different types of commercial vessels and uses, each with their own specific performance requirements.

One market niche where MarineDiesel engines are extremely competitive is the ski boat and parasailing boat market. These boats have very specific engine power requirements. Commercial, yet recreational also, these vessels need to be operational on a seasonal basis (usually), and every minute they are not operating can cost the owners thousands upon thousands of dollars in opportunity costs that are lost forever. They often use gasoline or petrol engines, and the Marinediesel engine’s compact size gives the operators a high torque, lower operating cost, diesel alternative.

Additionally, ski boats and parasail boats typically have highly compact engine compartments and need to minimize weight. The VGT Series is the most compact engine in its’ class on the market. In most cases, it is the ONLY marine diesel engine that can even fit into these types of vessels.

Ski boats and parasail boats require a torque curve that gives the optimal power at the lower RPM range for rapid takeoff, decreasing in need after the vessel is planning (This is why they often use gasoline engines, designed originally for automobiles). The NIRA ECU used by MarineDiesel allows us to optimize the performance specifically for these types of operations, giving the operator the torque that is needed, when it is needed. Add in the lower cost of diesel fuel (usually) and the much longer life cycle of a diesel engine versus a gasoline engine, and the best decision becomes immediately clear: Marinediesel’s VGT Series.



High Performance Pleasure Boating


Marinediesel is known for manufacturing high performance engines rated for government or military use and the extreme conditions under which these types of vessels operate. You may think, “Oh, I don’t need over-engineering for my boat that I only use on the weekends”.

However, what if you could put our engines in your pleasure boat at around the same price as other engines?
MarineDiesel’s VGT Series makes this possible.

Our engines are designed to take high punishment, operating in the roughest seas and in conditions that simply destroy engines made by our competition. We are the lightest, most powerful engine brand in our class.
Most pleasure boat owners use their engines under 100 hours annually. Typically, engines rated for recreational use will last 750 hours before requiring a major overhaul. Compare this to the 2,500 to 3,000 hours that MarineDiesel’s VGT engines will last. Quite possibly, the engines will last much longer than the average lifespan of a GRP hull of 20 years.

In other words….

The MarineDiesel VGT Series is the last engine you will ever need to purchase for your boat!
All the while giving you the level of performance demanded by some of the most rugged military craft on the market.

Don’t just take our word for it, though. Contact your local MarineDiesel distributor or vessel manufacturer and compare for yourself. We are standard or optional equipment on dozens of major boat brands manufactured all over the world. Ask to see how Marinediesel can give you high performance, long life, and reliability at a reasonable price.



Variable Geometry Turbocharger Facts


MarineDiesel’s VGT Series of engines was named as such for a very good reason: We use Variable Geometry Turbochargers (V.G.T.) in their design.

What is a VGT?

A VGT is a type of turbocharger that has internal vanes that open and close, changing the amount of air and exhaust that enter the engine. Thus, the geometry of the turbocharger changes, based on RPM.

Old, non-turbocharged diesel engines that are naturally aspirated were inefficient. Adding a turbocharger increased the amount of power and torque produced by the engine. By changing the geometry of the turbocharger, the compression ratio can be changed, thus making the engine more efficient, and substantially increasing the amount of power and torque produced, particularly at the low RPM range. Additionally, standard turbochargers tend to produce a lag at low RPM. The VGT solves this problem by further compressing the air into the engine.

The use of the VGT produces higher, sustainable torque across the engine speed range. In part, this is why our VGT Series of engines has a much higher level of overall torque, rather than the spikes, peaks, and valleys common in the toque curves of engines made by our competitors.

Since the power of the engine is increased by the VGT, it means that we produce, at only 515 kilos, the lightest, most powerful, 500 hp marine engine on the market.

Honeywell (the manufacturer of the Garrett VGT we use), has an interesting video that has an explanatory animation. We hope you find it interesting.





Eat my wake!



When you first board a vessel equipped with MarineDiesel’s VGT Series of engines, you may be thinking, “OK, this is just another sea trial or boat ride.”

Five minutes later, and this has actually happened, you might be surprised to hear yourself exclaiming, “Eat my wake!!!!

Don’t be embarrassed.

We understand.

You simply cannot appreciate the compact raw power of a MarineDiesel VGT engine without experiencing it first, especially after years of operating boats equipped with the wimpy, inline six cylinder engines made by our competition. The difference is astounding.

The raw exhilaration that comes from extreme acceleration.

The noticeable increase in performance.

Feeling secure in the knowledge that other boats, however they are equipped, cannot match your power.

Give it a try. See for yourself.

At MarineDiesel’s headquarters in Ängelholm, we have several company boats that we use to demonstrate our engines. We have an “open door policy” for customers and potential customers who wish to try our engines out. Simply contact us with the details of when you will be in Sweden, and we will be happy to schedule an appointment.







Five VGT Series benefits that are unique



The MarineDiesel VGT Series of marine engines stands alone in the marine market within its’ market segment. Quite frankly, there is no other competing engine that can compare with the VGT on technical and performance levels. Others may make claims, but the facts speak for themselves. No other engine in its’ class can equal these benefits:

  1. Highest power to weight ratio: The VGT Series are the lightest, most powerful marine engines available, making them ideal for high speed and high performance craft.
  2. Most continuous torque: Other engines may have torque curves with higher spikes, but only the VGT Series provides a high level of torque along the entire RPM range.
  3. Programmable ECU: Our competitors all use old technology Bosch ECUs to control their engines. Only the VGT Series allows multiple, customized engine MAPS.
  4. Smallest physical dimensions: The VGT Series is the most compact engine in the market in its’ class, Often, the only engine that can even fit into cramped, tight engine compartments.
  5. Longest MTBO: The VGT Series has the longest MTBO of any other engine in its’  class. This MTBO ranges from 2,500 hours to 3.000 hours. No other commercially manufactured engine in this class has a life cycle this long.

For a customized quote for your project, contact your local MarineDiesel distributor or you may contact us directly.



Best of 2014 – VGT Series vs Cummins QSB 5.9 – How do we Compare?



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.

The VGT Series of marine engines is MarineDiesel’s flagship product. We originally aimed to make the lightest, most powerful, most reliable engine available in the market, and we succeeded where others have not.

So, how does the VGT Series compare to others?


MarineDiesel VGT: Mid-range

Cummins QSB 5.9: Low

*Price will vary greatly based on many factors, including import duties and dealer markups, but in general


Cost of Spares:

MarineDiesel VGT: Mid-range

Cummins QSB 5.9: Mid-range

*Note: The Cummins engines are sold and serviced through the CMD network, which is largely focused on the recreational market



MarineDiesel VGT: Commercial / Military Medium to Heavy use

Cummins QSB 5.9: Recreational


Engine Block:

MarineDiesel VGT: V-8

Cummins QSB 5.9: Inline 6

*Inline cylinder arrangements tend to produce higher levels of vibration



MarineDiesel VGT: 500 kg

Cummins QSB 5.9: 658 kg


Fuel Consumption:

MarineDiesel VGT: Max 220 g / kWh

Cummins QSB 5.9: Max 235 g/kWh



vgt400 fuel


vgt400 curves

Cummins QSB 5.9 Power Curve

Cummins QSB 5.9 Power Curve




MarineDiesel VGT + Konrad Performance Package



MarineDiesel has teamed up with Konrad to offer the most reliable engine and sterndrive high performance package in the marine market today.

Sterndrives have some distinct advantages as a propulsion system over other types of drive. They are capable of producing very high speeds and yet, can offer good maneuverability at slower speeds. Traditionally, the Achilles Heel of sterndrive systems has been their reliability and high cost of maintenance. They just could not stand up to the high torque produced by diesel engines and heavy, continuous use by commercial or government users.

Until Now…

Konrad is recognized as producing the only reliable sterndrive propulsion system that can withstand heavy commercial or military use.


The Konrad sterndrive can last over 2,500 hours between overhauls.

This makes the Konrad sterndrives the only real option available to commercial users. Drives produced for use with gasoline engines, or for intermittent recreational use generally require overhauls in as few as 400 hours. Though often inexpensive to purchase, they can quickly become extremely expensive to own over the long term. For commercial users, this adds up to many thousands of dollars of expenses over time.

The sheet below illustrates the cost advantages of Konrad over other brands of sterndrive.

When paired with MarineDiesel’s VGT Series of engines,

Please take a look and send us a note if you would like to have a custom quote on a package for your vessel.

Konrad / VGT Package 

Konrad / VGT Drawing







VGT Series Installation Notes



We recently had a couple of yards that had a bit of difficulty installing our engines. Our global service facility, MDS, produced the following handy sheet of notes for use by shipyards in installing MarineDiesel VGT engines.

Please feel free to download it and use it as you see fit: