Choose the Best Small Cummins Engine for Your Yacht

October 15, 2020
Choosing the Right Cummins Engine for Your Yacht

Your yacht needs a high-quality engine to perform at its best and give you the greatest boating experience possible. This need is where Cummins boat engines come into play. They’re some of the most fuel-efficient, best small marine diesel engines around, and many yacht owners trust them to power their vessels. Before you invest in a Cummins yacht engine, you should know how to decide on the best one for your yacht.

As you look for your new Cummins diesel engine, take a moment to consider your power options, maintenance requirements, space needs and other crucial factors. These will ensure you get an engine that fits your yacht and gives you the performance you require.

Power Options

Evaluating your power needs is one of the first things you need to do before investing in a Cummins engine. Depending on your boat model, you can look up recommendations for the appropriate amount of power your yacht needs. You can also figure out which specific power range to choose from.

What is the best diesel marine engine? The answer comes down to your yacht’s requirements. Differences in horsepower, even in the appropriate power range, can dramatically affect your speed and handling, so consider a few options before you buy.

Calculating Horsepower

When you choose a Cummins engine, one of the first factors you should look for is horsepower. While some people think they should get the engine with the highest horsepower, this isn’t the best approach. Your yacht will have a maximum horsepower it can safely handle, and it should have a capacity plate stating the boat’s weight and horsepower limit. Exceeding these limits can cause your yacht to tip, so pay close attention to the recommendations for your boat.

Calculating Horsepower

To calculate your needed horsepower, you can use a basic equation. Since it takes 1 unit of horsepower to transport 40 points of boat weight at 20 miles per hour (mph), you should first determine your yacht’s weight. For example, if you have a 1,000-pound boat that needs to get up to 20 mph, you’ll need to choose an engine with 25 horsepower.

As you choose your engine, consider what you’ll be using your yacht for. If you plan to go on pleasure cruises, relatively low horsepower and a small Cummins engine may be the right option. However, if you plan to tow other boats or want to travel at faster speeds, you should likely go with a larger and higher horsepower engine. In addition to the yacht’s potential applications, try to account for the weight of potential passengers, equipment, and supplies.

Along with these weight factors, evaluate what appliances you’ll hook up to your yacht. For instance, fridge compressors or alternators will draw power away from propelling the yacht and use it for their own applications.

As you calculate your engine’s horsepower, list out your added drives to see how much horsepower will go elsewhere instead of to your propulsion. A 70-amp alternator may need somewhere between 2 to 3 horsepower, while a higher output 175-amp alternator will require somewhere between 6 to 7 horsepower. Always think about these extra drives when you select your engine’s horsepower.


Maintenance Requirements

All engines will need maintenance at some point. Most engines today are electronically controlled and computerized. These models are referred to as common rail engines, and they’re made to meet the Environmental Protection Agency’s (EPA) Tier 4 emission standards.

In the past, small cummin diesel engines for boats were much easier to maintain and troubleshoot. As engines have improved and become more complex to meet new emission requirements and perform better, there are now fewer maintenance tasks a yacht owner can perform safely. While you can still likely do cooling system repairs and change oil and fuel filters on your own, most other tasks will require specialized training and tools. Older engines had mechanical fuel injection systems, which were much easier for a regular boat owner to troubleshoot.

Today’s high-powered engines are often too complex for the average yacht owner to repair on their own. Attempting to perform maintenance tasks on these engines can even be dangerous, so it’s best for a professional to handle them. New engines will also need electronic diagnostic scanners to figure out what could be wrong with the motor.

As you search for a Cummins boat engine, check its maintenance requirements to see what you can handle yourself and what you should leave to a professional. To meet EPA requirements, you’ll likely need to purchase a newer engine, and as such, you should expect to invest in contemporary models.

Besides making sure you purchase a yacht engine that meets EPA requirements, you’ll also want to research the average costs of repairs for your potential small Cummins engine. By doing this research, you can better predict future costs and narrow your options to a motor that fits your financial needs.

Carrying Spare Components

A weather incident like a lightning strike can knock out your Cummins boat engine’s controls and electronics. When a lightning strike hits a yacht, it’s common for the engine’s onboard electronics to be destroyed or heavily damaged. In this situation, a trained technician must examine the damaged engine and replace the necessary parts.

When you’re out at sea, replacement parts can sometimes take a long time to get to you. Those who want to get back on the water quickly should carry backup components that can be used to repair their engines in the event of damage.

By having the parts available, a qualified technician can usually repair your engine faster and get you back up and running. Before you take your yacht out, you should work with a trusted supplier that will outfit you with spare small Cummins engine parts.

Space Considerations

What size motor should you put on your boat? Understand that you can’t plug any engine into your yacht and expect it to work. The space you have available for your new Cummins engine will determine the type you choose. Too small of an engine can lead to it lacking enough power for the yacht, while too large of an engine can take up too much space in the engine bay.

As you consider your diesel marine engine options, check out the following tips for choosing an engine:

Ensure accessibility: When you select an engine, pick a size that won’t make it difficult for people to access it. The most important thing is the ability to easily reach the engine’s service items, such as belts and filters and the impeller and dipstick. An engine that doesn’t fit in your engine bay or that has to be awkwardly placed can make it difficult to access these items, causing maintenance and inspections to take much longer.

Select flexible engines: Your Cummins powered boat may have some space constraints in your engine bay that make it challenging to find a proper engine. Sometimes, some suppliers can “hand” engines, which means the supplier swaps service items from one side of the motor to the other. If you have space constraints, moving these items around the engine can help fit it in the bay and facilitate easy access.

Check for proper ventilation: An engine needs the right ventilation to work efficiently. Installing one that’s too large for the yacht can lead to inefficiencies in ventilation. For example, much of a motor’s fuel is used up in heat losses, with the fuel going through the block cooling system. As such, a yacht engine shouldn’t be larger than the cooling system can handle, and the bay should allow for proper ventilation.

Examine insulation: Usually, engine bays feature insulation to keep the engine noise away from passengers. When you purchase an engine, you should consider how thick the insulation is and how the motor’s size will fit with it. Thick insulation can make it difficult for people to access the engine if the motor is too large. Since boat owners will often move items in the engine, such as filters and raw water strainers, it should be small enough for them to access easily.

Marinization Standards

There aren’t many reliable engine providers for boats, especially those designed to work with yachts. Some non-marine engine manufacturers have converted their motors for marine uses. However, when you choose an engine for your yacht, you should check that the engine manufacturer has marinized their motors appropriately to draw the best performance from them.

Some marinization standards to look for in small Cummins diesel engines include fuel economy, reliability, maintenance cost, quick-start ability, and operational sound. These standards will directly relate to your experience with the engine and its safety. Discounting them can lead to your motor performing inadequately and running into more frequent maintenance needs.

One major marinization standard you should check for is the motor’s ability to handle corrosion. Often, there’s a small temperature gradient between the water surrounding the boat and the engine temperature. If the small Cummins engine is properly marinized, it should handle these temperatures efficiently. A high-quality engine that meets marinization standards will have corrosion-resistant parts that slow down the need to replace them.

Companies with a long history of producing marinized engines are often a buyer’s best bet. Subsequently, a Cummins boat engine is an excellent choice. The company has been producing some of the best small marine diesel engines since 1919, with the tradition continuing to this day.

Since they know boats have many different needs, Cummins provides everything from small marine diesel engines to larger models, with power ranging from 5.9 to 95 liters. Due to the range of power, you can find a Cummins engine that meets your yacht’s requirements. Cummins’ high marinization standards also mean you get reliable and durable parts.


Drive Train Types

Your small Cummins engine’s efficiency relies on the type of drive train you choose. Your drive train directly affects where the engine goes in your yacht, freeing up more space for other purposes and affecting the boat’s performance. Some popular drive train types that yacht owners can choose from are below:

V-drive: V-drive inboard systems sit in a yacht’s bottom rear and feature forward-facing motors. One benefit of a V-drive inboard system is that its rear placement enables the yacht to have more space in its interior cabin. This model is generally used by cruising yachts that don’t need high performance, as there’s some power loss due to the complexity of the V-drive’s transmission.

Direct drive: A direct drive system sits close to the center of the boat. It’s a great engine for boats that prize energy efficiency and simplicity, as it can usually be easily serviced and loses minimal horsepower. If you want more space in the center of your yacht, the central location of the direct drive may make you want to choose a different drive train.

Saildrive or outdrive: Saildrives and outdrives are popular on smaller yachts and are fairly easy to install. These transmission systems are used when the inboard yacht engine uses a horizontal output shaft. Since you can steer outdrives, boat owners often use them on catamarans. Some benefits of saildrives include their smaller, horizontal size, reduced vibrations, lessened propeller walk and greater efficiency. One recurring concern with saildrives is their tendency toward corrosion and greater maintenance needs.

Hydraulic drive: A hydraulic drive allows your small Cummins engine to be placed at a distance from the drive train or offset from it. Instead of using a traditional gearbox and engine to power the propeller shaft, this type of drive train uses a hydraulic motor. A hydraulic drive train will have a hydraulic vane pump installed on the engine’s side, which helps power the propellor shaft. These engines aren’t exceptionally efficient, which keeps some yacht owners from relying on them.

Diesel-electric drive: Diesel-electric drives are gaining popularity since they can be installed far away from the yacht engine. The diesel and electric systems can be used independently, giving boat owners more flexibility in their power options. An advantage of these drives is that they can power multiple propellers from one engine. These are a great backup for a single-engine yacht, as they can use the engine power from the yacht’s genset to propel the boat if needed.

Hybrid drive: A hybrid drive engine mixes a diesel engine and electric motor on a shaft. The power sources from either diesel or electric systems can be used together or alone. An advantage of a hybrid drive is that it’s a highly efficient power source, making fuel last longer. These drives are also quiet power sources and feature a compact construction.

Find Your Cummins Engine Parts at Diesel Pro Power

Whether you’re looking to repair a damaged Cummins boat engine or outfit your yacht with spare engine parts for the future, you’ll benefit from working with Diesel Pro Power. We have a vast inventory of Cummins engine parts that make finding the exact required component easier than ever. We’re proud to have served over 24,000 customers, and our excellent customer care team is ready to help you determine the best parts for your engine.

Browse our selection of Cummins engine parts today. If you have any questions, feel free to contact us.

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