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Commercial Marine Auxiliary

(15 to 500 kWm (750 hp))

We are at home on the west coast, so we know the commercial marine auxiliary business. With decades of experience, we are professional packagers of auxiliary power units to run deck gear, towing winches, pumping systems, refrigeration, and so on.

Custom Marine Auxiliary with two pumps off the aft (rear) end and alternator at the fore (front) end.

We can custom build combination auxiliary generator sets with both hydraulic and mechanical power capability, for example.

Our customers are the leading towing, transportation, fishing and marine services providers. They rely on the durability and economy built into Kubota and John Deere diesel engines.

We can save you money on installation costs by providing complete turnkey packages with controls that minimize shipyard installation time. These sets are pre-wired and mounted for ease of installation.

We are happy to work with the naval architect, shipyard or vessel owner to design the right package for the vessel. Please contact us.

Checklist 2Checklist of Things to Consider

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The following items are not by any means a comprehensive list of requirements. They are intended to get the vessel owner or operator thinking about what it will take to successfully install a marine auxiliary system. Depending upon the vessel, this can be a simple or complicated process. Much depends on what the engine will do, how long it will operate, what the duty cycle is and so on. Each of these headings does need consideration and we suggest that you consult individuals or firms with experience to assist you.

Power Output

Think about the average and maximum loading.

  • What are the ratings of hydraulic pumps in pressure and flow?
  • What loads are simultaneous?
  • What loads never operate simultaneously?

While it is never a good idea to overload an auxiliary engine it is also harmful to operate an engine under prolonged light loading. Choosing the right power output is essential for satisfactory life.


Often, marine auxiliary engines are fitted into limited spaces, so be sure that all of the normal service points (e.g., filters, oil levels) are accessible.  Can the valve cover be removed for valve set maintenance?

Cooling and Ventilation

What cooling system will be used?
Are hull modifications required?

Typically we do not recommend sharing cooling systems with any other engines so the auxiliary engine needs to have an adequate cooling system to handle its maximum loading in the highest ambient conditions. Cooling system degradation takes place over time so it is prudent to allow for this in the initial design.

Engines require cool air for efficient combustion. As well, heat is radiated from the engine and to a lesser extent, from the driven components. Fresh air needs to be provided to maintain a satisfactory engine room temperature under the warmest conditions that the vessel may encounter.

Noise and Vibration

This is very vessel specific. Acceptable noise and vibration levels are different on different vessel types. Sound is created by the exhaust system and it is also created by mechanical means. Advance planning for sound attenuation includes having sufficient space for a suitable exhaust system and, if required, for an enclosure.

Vibration isolators minimize both noise and vibration transmission to the hull. Reducing noise and vibration can make a vessel a much more pleasant place to work, sleep or play.

Torsional Compatibility

Auxiliary engines are often called upon to drive multiple items. Sometimes, for example, a generator may be run off the front of the crankshaft while a clutched or live hydraulic pump is driven from the flywheel end. It is important to know that these loads, in a worst case situation, cannot damage the engine. A torsional vibration analysis (TVA) provides theoretical modeling that assists in selecting couplings that will protect the engine from serious harm.

Typical Examples

Combination Troller, Longliner and Tuna Boat
  • A John Deere engine running at 1700 rpm developing 60 hp. driving a refrigeration compressor or from the flywheel end via a mechanical over-center clutch.
  • A 2.77 C.I.D. hydraulic pump is close coupled to the auxiliary drive pump pad delivering 20 gallons/minute at 2000 psi oil flow for deck gear and a 2″ wash down hydraulic driven salt water pump.
  • Mounted underneath the skid is a 7 kW 1800 rpm belt-driven AC generator.
  • The over-center clutch added some length to the unit, but allows the refrigeration compressor to be disconnected during an “ice fishery”.
West Coast Crabber
  • A John Deere engine running at 1800 rpm providing 35 kW of AC electrical power off the flywheel.
  • Inline off the front of the crankshaft, a 4.21 C.I.D. pressure and flow compensated hydraulic pumps delivers 32 gallons/minute of hydraulic oil to run deck gear and a large sea water live tank pump.
47′ Custom-built Passagemaker Pleasure Boat
  • A 12 kW heat exchanger-cooled Kubota generator set.
  • An oversized Stamford generator winding “049” to start the air conditioning units and a front mounted hydraulic pump to power the “get home” drive.
36′ Prawn Boat
  • A 20 hp Kubota-driven generator set directly connected to a Carrier refrigeration compressor.
  • A custom drive plate/coupling.
  • Remote-mounted control panel and safety shutdowns.
60′ Offshore Squid-jigging Vessel
  • Two John Deere engines running 70 kWe AC generators to replace old 70 kWe competitor’s generator sets.
  • A custom-fabricated mounting skid to bolt down in the same place as the old generators.
Large Steel Fishing Dragger

150 kW AC John Deere diesel generator set to power all processing and freezing on board.

Offshore South Pacific Tuna Boat

40 kW and 60 kW John Deere-driven AC generators and hydraulic drives for freezers and tuna pullers.

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