MAN D2676 engine for fishing boats in Alaska

MAN Engines for Commercial Shipping

Salmon Fishing in Alaska

MAN engines drive the boats which are used to catch 37 million salmon within four weeks.

In 2015, in Bristol Bay, Alaska, the largest red salmon migration for 20 years has been predicted. 54 million fish are aiming to reach their birthplaces in the five largest tributaries of the bay in order to lay their eggs there and continue the next generation. Beforehand, however, they have to pass 1,800 fishing boats, the operators of which have been waiting for generations for the world-wide largest migration of wild salmon every year. Over a period of four weeks, they will be permitted by the Alaska Department of Fish and Game to catch almost 70% of the arriving fish. What they need for this is experience, a good crew, and a reliable machine. This is because the conditions along the coast of the wilderness of Alaska are harsh – and not just due to the swell of the sea. The competition is fierce in the precisely defined fishing grounds; here, the boats maneuver closely alongside each other and fight for the best spots.

A key factor for the fishermen lies in the reliability of their boats. Every day, every minute that they can cast out their nets counts. In order to utilize this time as effectively as possible, since 2014 the boat manufacturer Mavrik Marine has equipped its gillnetter boats, which are specifically designed for Alaskan fishing, with a 730 HP diesel engine from MAN. The fact that just one drive engine is used, offers one thing above all: more space for the salmon that is caught. Previously, it was usual for two engines to be fitted; this is no longer necessary, however, due to the extremely reliable unit from MAN. Due to the compact design and the low weight of the in-line 6-cylinder MAN R6-730, this effect is increased further. In practical terms, this means that the boats can take on board a higher load before they have to travel to the nearest supply vessel (tender) to unload. The time that is saved by this can be used by the fishermen to catch even more salmon.

The gillnetters are characterized by their high performance and precise maneuverability.

On the way to the tender and back, the flexibility of the engine stands out. The working boat is designed in such a way that it glides over the water when unloaded and when returning fully loaded, acts like a tugboat. The engine is designed so that it provides a consistently high torque over a large engine speed range. It is exactly this characteristic that Pete Bjazevich, who has been working in the fishing industry for more than 40 years, appreciates. When asked what he otherwise values in a boat engine, he replies: "I want a simple engine that‘s easy to maintain; that is efficient and that also offers smooth operation."

In order to be able to carry out maintenance work on dry engines with low vibration support, it was ensured that enough space was available. Once again, the compact dimensions (length/width/height 1,634x910x1,079 mm) of the MAN engine provide the crew with benefits. Efficiency and smooth running are ensured by the second generation Common Rail injection system used by MAN. The cylinders always receive exactly the right amount of diesel that they need for combustion. This not only increases efficiency, but makes acceleration noticeably more active. The boat therefore reacts more quickly to changes in speed, something which is a great advantage in Bristol Bay: The area which in which the fishing is allowed is limited to a small section in front of the river estuaries in which the fishing boats hurry about. The best places are directly at the boundaries out to the bay which are monitored by the officials of the Alaska Wildlife Troopers. To cast their nets here, the skilled captains need a boat that can react quickly.

The MAN R6-730 leaves enough space in the engine room for maintenance work

The agility that is achieved also contributes to safety. When there are so many boats sailing close to each other, it is easy to get in the way. In order to avoid crashes, it is important to react quickly as the one thing that is more important to the fishermen than the salmon is the welfare of the crew.

For them, the boat turns into a kind of second home during those four weeks in this remote corner of Alaska. Here, they brave the elements and the water, which is just 10° Celsius. Even though it is hard work, the working conditions on the boats have improved due to the new MAN engines. Diesel knocking is a thing of the past, vibration and noise were reduced to a minimum, and due to the clean combustion from engine start onwards, the typical diesel exhaust smell is also gone.

But not only the smell has gone; as a whole, the exhaust emissions are cleaner than ever. With a reduction in nitrogen oxides (NOx) by 20% and a reduction in particle mass (PM) by 40%, the engine meets the requirements of the emission standard for working boats EPA Tier 3, which has been applicable since 2014. This has been achieved purely with measures carried out inside the engine and without exhaust gas recirculation or exhaust gas aftertreatment. Despite the improvements in the area of emissions, under full load the engines use only marginally more fuel than before. To be precise, during operation with the lowest specific fuel consumption, the engine provides both a maximum torque and achieves the lowest point for wear. This type of optimal operating point characterizes the marine engines of MAN, allowing the boat owners more economical and efficient drive. The MAN engines therefore play their part in preserving nature in this almost untouched place of the Earth. Whilst salmon stocks are decreasing almost everywhere else on the planet, in Bristol Bay there is still the largest migration of king salmon. This is not least due to the unpolluted water which has a direct influence on the fish caught. Salmon is a healthy and sustainable food stuff which defines the economy and ecology of the region. So that it remains this way, the fishermen place great emphasis on quality and being environmentally friendly.

3D view of the twin pipe water pump with integrated low temperature pump

The Common-Rail-System is injection technology which is used to provide a constantly high injection pressure, irrespective of the speed of the engine. With a high pressure pump, up to 1,800 bar of pressure can be generated which is then available to every injection nozzle via a joint distribution rail (Common Rail). The higher the pressure, the more fine the atomization of the fuel in the cylinder, optimizing the combustion and meaning the engine is more efficient overall. Furthermore, the injection is also controlled electronically so that numerous injections are possible per combustion cycle. This makes combustion more even, meaning that the engine runs more smoothly and fewer particles are released. Due to the decoupling of pressure generation and injection over the entire speed characteristic, high injection pressures are also available at low engine speeds.

MAN is currently the only manufacturer of in-line 6-cylinder diesel engines for marine applications using state-of-the-art Common-Rail-Systems – and has been doing so since 2004.

Gillnetter PB32 - Propboat

Technical data
Ship type Gillnetter
Name PB32 – Propboat
Shipyard Mavrik Marine
Length 9.75 m
Beam 4.37 m
Draft 0.89 m
Displacement 10.2 t
Max. load of fish 8.16 t
Fuel tank 1,438 l
Crew 4
Gearbox ZF360
Propeller SS 30” Conventional Prop
Name MAN R6-730
Cylinder and arrangement 6 cylinder, in-line
Operation 4-stroke diesel engine, water-cooled
Turbocharging Exhaust turbo charger with intercooler
Charging pressure governing system with wastegate
Valves 4 per cylinder
Injection system Common Rail direct injection with electronic diesel control
Engine lubrication Closed system with pump-fed lubrication, cooling system, and filter
Cooler Heat exchanger with engine and seawater circulation
Engine control Electronic injection control (electronic diesel control)
electronic engine monitoring including diagnostic unit
Characteristic engine data
Capacity 12.82 l
Max. power 537 kW (730 HP)
Nominal speed 2,300 rpm
Max. torque 2,450 Nm
In engine speed range 1,200-2,100 rpm