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Benefits of Repowering

Installing a new, technologically advanced YANMAR engine will instantly breathe new life into your boat.

With the right system, you will benefit from:

  • Improved acceleration, power, and responsiveness
  • Lower running costs and increased uptime
  • Enhanced fuel efficiency and lower environmental impact
  • Upgrade to the latest electronics, controls, and diagnostics with interconnectivity to modern multi-function displays
  • An overall smoother, quieter, and more pleasurable boating experience

When to Consider Repowering

YANMAR marine engines are renowned for their durability and long lifespan. The point at which your YANMAR or other diesel system will need repowering cannot be determined based on the number of operational hours alone. An engine’s longevity is often subject to how regularly and consistently you run your system.

You should consider repowering if:

  • Your existing engine is becoming increasingly unreliable
  • You are losing horsepower
  • The engine is consuming too much fuel
  • Maintenance costs and downtime are rising


Depending on the complexity of the project, replacing an inboard engine can take between one to four weeks once it arrives at the yard. However, the more time and consideration that can be put into planning the repowering project beforehand will pay dividends when the installation starts.

This includes:

  • Choosing your installation center
  • Selecting your new engine
  • Choosing new accessories/technology you may wish to include
  • Allocating delivery time for all needed materials
  • Identifying any additional work that might be required

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Full Repower Guide

What Engine Do I Need?

When determining the engine best suited to your repowering needs, there will be a number of things to consider, centered around the type of boat you own, what you are looking to gain, and your engine room space and current engine footprint.

Displacement hull vessels will normally require a like-for-like power output while planing hull boats, more sensitive to weight, may benefit from the improved power to weight ratio offered by modern diesel engines.

With the advances in technology and materials used in YANMAR’s modern engines, it is often possible to achieve the same or higher power output with a smaller and lighter engine, boosting both acceleration and top speed. However, keep in mind that a more powerful engine may require a different marine gear, stronger engine beds, larger prop shafts and propellers, additional fuel tank capacity, and reworking of the existing intake air and exhaust system.

It is best to consult with a certified YANMAR dealer to determine the right propulsion system for your needs.

Choosing the Right Installer

A successful repowering project relies on two key aspects: selecting the correct engine for your boat and commissioning a qualified YANMAR installer.

Finding a technician with the right level of expertise and skill will help achieve a great outcome. The following tips are a guide to how you can make this selection process as smooth as possible.

  • Only commission an installer who has visited and inspected your vessel.
  • A competent installer should ask relevant questions about your boat and how you operate it.
  • Look for an installer who has repowered vessels and/or completed projects of a similar scale.
  • Ask for references that you can visit or speak with, as well as research the overall reputation of the yard.
  • Make sure that an installer’s work conforms to all relevant regulations and legislation.
  • Ensure that you receive a detailed quotation and a full breakdown of technical costs. On occasion, certain costs may be difficult to define upfront, such as converting a gasoline tank to diesel. However, these should be discussed in detail before work commences.

Rebuild vs. Repower

Rebuilding an existing engine(s) is an alternative option to repowering. This route is commonly perceived to be an easier and less costly choice. However, this may not always be the case, and if it is, these may only be short-term benefits.

Many existing parts are often not replaced during a rebuild. These parts can include, but are not limited to, the alternator, starter, and water pump. The remaining life expectancy of these parts cannot be predicted and could require further maintenance, downtime, and expense. Rebuilding an engine could also take more time and could present additional, unexpected costs.

By contrast, the installation of a new YANMAR engine guarantees that all of the components are new and the system is covered by our extensive manufacturer’s warranty. It will also likely incorporate the latest state-of-the-art technology, which will deliver rewards on both an economic and performance level.

Ultimately, the decision between the two options relies on individual circumstances and requirements. Consider this: if a rebuild is going to cost about 40% or more than the amount to install a new engine, then repowering may be a sounder investment.

Cost vs. Value

Repower your boat because you plan to keep it and reap the benefits of the new engine yourself. The value of your boat will certainly increase with a new engine, but rarely enough to recoup the costs immediately if you are only repowering with the intent to sell. The same is generally true if you convert from gas to diesel. The boat’s value will increase, but not likely enough to fully pay for the conversion.

Repower Because of Engine Failure

When an engine goes down, you need to repower your vessel regardless of choice. Whether your boat is used for recreation or for light duty commercial purposes, our goal is to get you back on the water as quickly as possible.

  • What if I have multiple engines and only one goes down?
    If one engine fails and needs repowering, consider the remaining life expectancy of the other engine. If the other engine is nearing its end of lifespan, it is best to replace both engines at the same time. When replacing both engines, we recommend upgrading to the latest engines to benefit from the performance and efficiency gained by the latest advances in technology. If the other engine still has about 50% or more life expectancy, replacing only the down engine might be the best choice. 

Emissions Compliance

If your boat has an engine(s) not currently compliant with the latest emissions regulations, there are several things to consider when repowering.

Is there a current emission compliant engine model that fits the power requirements and space needs of your boat?

  • If yes, it is highly recommended by the emissions governing authorities to repower with engines meeting current emissions regulations. There are some cases where exceptions can be made. Please contact your regional dealer or distributor to inquire.
  • If there is not a current emission compliant engine that fits your boat without significant modifications, then you might qualify for a non-compliant replacement engine.

Advantages to repowering with an emissions-compliant engine:

  • Enjoy the benefits of a significantly more fuel-efficient system.
  • Advances in performance and efficiency from the latest common rail technology provide a cleaner, smoother, quieter, and more powerful engine experience.
  • See YANMAR engine data and real time diagnostic troubleshooting codes at a glance with advanced electronic controls and displays that come standard, or as an option, with all current YANMAR compliant engines.

Why Choose YANMAR?

YANMAR marine engines set the global standard in performance, efficiency, and endurance.

YANMAR’s reliable engines are well known to have a low total cost of ownership.

YANMAR has the largest sales and service network in the marine industry, covering over 130 countries worldwide.

YANMAR is the only manufacturer to bring the benefits of common rail technology to smaller vessels, providing 5x Best in Class standards – Clean, Interconnective, Quiet, Powerful, & Fuel Efficient.

YANMAR is the inventor of the modern diesel engine and is continuing to innovate solutions that push the boundaries of marine propulsion into the next century. Meeting the demands of the evolving, modern consumer by providing advanced and sustainable technologies is proudly at the forefront of development at YANMAR Marine International.

Ready to Get Started?

Find your local authorized YANMAR distributor or service center here.

YANMAR Repower Guide

Download our guide to repowering, which includes a useful checklist of what to plan for when approaching a repowering project

Repower with YANMAR 6LFs

Certified YANMAR dealer Motonáutica Balear, Mallorca, completes the installation of two YANMAR 6LF530 diesel engines on Magnum Marine 40 motorboat Adriana to raise performance to a new level.

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