Marinediesel Recommends: Seacross

seacross screen

Though Marinediesel equips many different types of vessels, we always have specialized in high speed and high performance craft, whether used by government, commercial, or recreational users.

Navigation is often difficult on high speed boats. Above 50 knots, operating a boat can easily become dangerous. Reduced reaction time and increased forces from slamming mean that fiddling around with complicated software or equipment becomes more of a distraction than an aid.

Fortunately, there is a solution: One that Marinediesel strongly recommends.

Seacross is a Swedish navigation system manufacturer that specializes in designing systems specifically for high speed craft, and meeting the unique challenges those vessels present to their operators.

The Seacross system is highly intuitive to learn and use, not cluttered up with a lot of useless options.  in addition, the Seacross system can be integrated with many different components, and can be customized to a user’s specific needs. This is a distinct advantage over other products designed for large, slow moving ships or workboats. At speeds over 50 knots, there is simply no time to try and center a mouse pointer on a tiny option hidden in a software icon.

We urge you to give Seacross a try on your next high speed vessel project. There simply is no better alternative to Seacross in the market.

Visit the Seacross website

All of our curves

We recently had a request from a customer to show all of the power and torque curves of our VGT Series of engines on a single graph, for “at a glance” comparison purposes.



Take a look at the graph. Note how very flat power and torque curves are on our engines, and compare them to the curves of our competitors. The one below is for a Cummins QSB 6.7, medium intermittent duty (Comparable to VGT 450):

cummins torque 6.7


Note the spike in torque on the Cummins. Why does this matter? Well, the Cummins may have a higher maximum torque level, but it occurs at a spike, at a single RPM level. The VGT provides more torque, over a wider RPM range. This translates into lower cruising RPM (thus less fuel consumption) and more power at those speeds.


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.







Surface Drive Propulsion Packages


Continuing from yesterday’s article about propulsion packages, there is one type of propulsion that will always provide the highest top speed on any vessel: Surface drives.

MarineDiesel has teamed up with France Helices to offer the France Helices SDS surface drives to our customers, as a package with our engines.

Of all of the propulsion types available in the market, surface drives will give the highest top speed and, in the case of articulated surface drives, the greatest level of control and maneuverability on high speed or high performance vessels. In layman’s terms, surface drives use the cavitation produced by the propellers as thrust, while minimizing drag, thus ensuring extremely high top speeds. They are designed to force a vessel to plane quickly, and efficiently. Of course, on high speed vessels, proper calculations are essential to achieving the required performance levels. France Helices specialize in designing propellers specifically intended to give required performance levels. In other words, the drives are customized to the vessel, and not the vessel customized to the propulsion.

When are surface drives appropriate?

  1. Any vessels required to achieve top speeds over 50 knots (In some cases, surface drives are the only way to achieve these speeds).
  2. Vessels that will operate in shallow draft areas.
  3. Vessels that will operate in dirty or polluted water.
  4. Vessels that require extremely high levels of maneuverability, crash stop, or acceleration.
  5. Vessels that will operate in rough seas.

When are surface drives not the best choice?

  1. On vessels that will operate at speeds below 30 knots a substantial amount of the time.
  2. On vessels used for boarding (like pilot boats).
  3. On vessels that will operate with people in the water nearby (rescue craft, dive boats).
  4. On vessels that are overweight by design (large displacement variations).
  5. On vessels that have displacement or semi-displacement hulls.

On surface drive equipped vessels, the calculations can be somewhat involved, requiring a substantial amount of information on the vessel. Visit the France Helices website for more information.

If you would like a quote on a performance package with MarineDiesel engines and surface drives, contact your local MarineDiesel distributor or dealer today, or MarineDiesel directly, for a customized quote.







When should you repower your boat?


On this blog, we often mention MarineDiesel engines as being suitable for repowering a variety of different vessels and applications. Indeed, perhaps 20% of our new engine orders are destined for repowering or retrofitting projects.

When should you decide that a repower if preferable to simply rebuilding the engine?

This is often not an easy decision to make. Most diesel engines can be rebuilt three or four times without any problems. It is important to note, however, that every time that an engine is rebuilt, no matter how competently, there will always be a degradation in engine performance. This should be a concern when deciding, “Should I rebuild?” or “Should I replace?”

Suppose your engine has never been rebuilt before. It has only been used in fresh water. It is still delivering an appropriate amount of horsepower, but starts sluggishly and you are needing to replace different components more often as they wear out. In this scenario, rebuilding the engine is probably a good bet. It is far less expensive than buying new, and it is just simply starting to near the point of requiring a complete overhaul.

In a different scenario, assume an engine has had extremely heavy use, always in salt water, and under a wide variety of throttle settings. The engine has had some hard wear. Symptoms start going beyond merely sluggish starting and may include smoke, noticeable decreases in power, and high increases in the number of spare parts required to keep it operating. The engine may have been rebuilt one or more times previously. This engine is a good candidate for replacement, and repowering.

Ultimately, the decision usually comes down to cost. Rebuilding an engine, on average, costs approximately 60% of the cost of buying new, assuming the use of OEM parts and keeping in mind the wide variation in labor costs around the world. Additionally, unless being replaced with the exact same engine make and model, new mounts, couplings, shafts, drives, and possibly propellers will also need replacement.

It is also important to note that engine technology has progressed at nearly light speed over the past two decades. In particular, emissions requirements have led to engines that are smaller, more powerful, and far more fuel efficient than even identical brands were twenty years ago.

Indeed, fuel efficiency should never be neglected in making this decision. Gains and operating cost reductions from more fuel efficient operation can easily cover the cost of repowering your vessel, as can the reduced maintenance that owners of new engines will experience.

If you would like a custom quote on your repowering project, contact your local MarineDiesel distributor today, or contact us for a free, no-obligation proposal.




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.



Vessel Performance and Load



“Load” is one of those terms that gets thrown around in the marine industry, and the meaning is often blurred. What, exactly, is meant buy load, and how does it impact vessel performance.

Load can refer to either:

  • Engine load
  • Vessel load (tied to displacement)

These two things are also tied together.

Most high speed vessel are designed with a planning hull. In other words, the hull is designed to lift itself out of the water when power is introduced. It is a question of physics and opposing forces. In absolute simplest terms, the hull is experiencing:

A force downwards. This is displacement, or the weight of the boat. If more weight is added, the greater the force necessary to lift the boat.

A force backwards. This is resistance. As the propulsion system pushes forwards, the resistance increases. Additionally, anything sticking in the water, like the drive, rudder, propeller, or spray rails, produces drag, which increases resistance.

A force upwards. This is buoyancy.

A force forward. This is propulsion.

There are other forces and impacts on performance, such as trim of drives, wind, intakes, etc. The above are the most important.

So, as is evident, vessel performance is a question of balance. In order to make the boat move forward and up, enough power needs to be provided to overcome these forces. There is no magic or voodoo involved. It is simply a question of physics. Depending on the extent of the problem, a solution may or may not be able to be found.

So, on vessels with performance problems, the first diagnostic is usually weight. More weight means more displacement means the engine must work harder to make the boat plane. This is engine load. This is also why naval architects often pull their hair out at design changes. Any additional weight will impact performance. Put a marble floor in a recreational yacht? Performance will suffer. Extra guns and ammunition on a military boat? Performance will suffer. Add 10 additional passengers on a water taxi? Performance will suffer.

Load on the engine. Load on the hull. In both cases, speed, maneuverability, and overall performance take a hit.






Pyrometers and Exhaust Gas Temperature



Exhaust gas temperature (EGT) is probably one of the most important leading indicators of engine failure. A pyrometer is a device that can indicate the temperature of gasses at different points along the engine’s exhaust system. Therefore, in order to get the best diagnostic information from pyrometers, they must be positioned or mounted at the proper locations along the exhaust system, since temperatures will vary along different points.

Pyrometers can help diagnose the following conditions, prior to severe engine damage:

  • Cooling system problems
  • Combustion problems (air / fuel mix)
  • Fuel system problems

Note that by “problems”, we mean catastrophic, replace the engine problems.

A good example of this temperature variance is with the turbocharger. Exhaust gas temperature can indicate problems with the turbocharger, so a pyrometer placed before and after the turbocharger will give an indication of potential for failure. Between intake and out, the temperature differential can be 300 degrees C or more.

However, MarineDiesel uses Variable Geometry Turbochargers (VGT) with its’engines. As the inlet varies in size, the temperatures will normally fluctuate as the aperture of the turbocharger changes shape. Therefore, how is change in temperature a leading indicator? Simple. What you are looking for is temperature anomalies, outliers, or changes over time. Your engine manual gives an indication of the proper temperatures and the levels that should be present. Actually, this becomes an issue more with experienced engineers. They have the knowledge of one or more engines, but every engine manufacturer designs their engines differently, and the ratings are different, meaning temperatures will be different between manufacturers make and model. Hence, the standard “refer to the manual” line, cliche though it may be. With most engines, the exhaust gas temperature should range, normally, from 500 to 700 degrees C. Again, this will vary.

Also important to note: Engines are tested and rated in factory test cells, where conditions are constant. In the real world, vessels operate in a wide variety of conditions, climates, and use. Heavy loads typically mean higher exhaust gas temperatures. These all have an impact on exhaust gas temperature, and adjustments to what is “normal” are required under differing conditions.

Another indication provided by pyrometers is that of emissions. Exhaust gas temperature can help diagnose incomplete combustion and non-compliance of emissions.




MarineDiesel User Poll: Engine Performance



Today’s article is the latest MarineDiesel user poll (no registration required and no cookies kept), related to aspects of engine performance that make your decision as to engine choice.

We hope you find it interesting.

[socialpoll id=”2241265″]



Multi-engine Installations



The picture above is an example of a triple engine installation MarineDiesel completed. Though the vast majority of our marine projects involve single or twin engine installations, we occasionally receive requests to power triple or even quadruple engine projects.

Indeed, as is evident in the photo above, engine compartments are often very limited in the amount of available space, and the compact size of the MarineDiesel V-8 engines means that our engines are often the only engine that will fit in some engine compartments.

Triple installations are usually more expensive than twin installations of higher horsepower engines, and there are other challenges as well, particularly on vessels that use propellers for propulsion. On these vessels, the nature of propellers means that vessels will have a tendency to “pull” in one direction of the other, due to the torsion of the propellers themselves.

However, a triple installation also offers additional redundancy, and normally lower weight than twin installations with larger engines.

So, which is preferable?

Normally the decision comes down to cost, though weight and space constraints also have an impact.

Nonetheless, the compact power of MarineDiesel engines means that multi-engine installations are far less uncertain regarding performance and are a cost effective alternative to providing high power in a limited space.

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