Governing Boat Speed: Installing A Governor

Marine vessels need a speed control system to govern the speed of the propulsion plant being used on board. This is because there can be a large number of variations in engine load, which may damage the engine and cause loss of life and equipment. Governors are an important component of a boat's engine, as they help to maintain the mean speed of the engine within certain limits, under fluctuating load conditions. They do this by regulating and controlling the amount of fuel supplied to the engine, and limiting the speed of the engine when it is running at no-load. While mechanical governors are cheap and simple in construction, hydraulic governors are more commonly used in ships today due to their high power output, accuracy, precision, efficiency, and ease of maintenance.

The function of a governor on a boat

Marine vessels need a speed control system to control and govern the speed of the propulsion plant being used on board. This is because there can be a large number of variations that arise on engine load, which may damage the engine and cause loss of life and equipment. Governors are, therefore, an important safety feature on boats.

A governor is a system that is used to maintain the mean speed of an engine, within certain limits, under fluctuating load conditions. It does this by regulating and controlling the amount of fuel supplied to the engine. The governor limits the speed of the engine when it is running at the no-load condition, governing the idle speed, and ensuring that the engine speed does not exceed the maximum value specified by the manufacturers.

There are different types of governors, including mechanical, hydraulic, electro-hydraulic, and electronic governors. Mechanical governors are cheap and simple in construction, but they have a small power output and are not suitable for exact speed control. Hydraulic governors, on the other hand, have a high power output, high accuracy, and precision, making them suitable for medium to large engines. Electro-hydraulic governors combine an electric governor with a mechanical-hydraulic backup, allowing for manual control in case of failure of the electric governor. Electronic governors provide faster responses to load changes and can be mounted remotely from the engine.

Governors are fitted in auxiliary diesel engines, generators, and alternators on ships. They help maintain the engine speed within a safe range, preventing damage to the engine and ensuring the safety of the vessel and its occupants.

How to adjust the engine or fuel injection pump

Governors are systems that maintain the mean speed of an engine by regulating and controlling the amount of fuel supplied to it. They are necessary to control and govern the speed of the propulsion plant being used on board, as large variations in engine load may damage the engine and cause loss of life and equipment.

There are several types of governors, including mechanical, hydraulic, electro-hydraulic, and electronic governors. Mechanical governors are typically used in small engines and consist of weighted balls or flyweights that experience a centrifugal force when rotated by the action of the engine crankshaft. This centrifugal force is used to regulate the fuel supplied to the engine via a throttling mechanism connected to the injection racks.

Hydraulic governors are similar but use a control valve to direct hydraulic fluid, which controls the fuel racks and, consequently, the power or speed of the engine. Electro-hydraulic governors combine a mechanical hydraulic backup with an electric governor, allowing for manual control in case of failure of the electric governor.

Electronic governors provide engine speed adjustment from a no-load condition to a full load. They consist of a controller, an electromagnetic pickup, and an actuator to carry out speed control and regulation. The electromagnetic pickup has a magnetic field that changes as it is installed above the flywheel teeth, and this change in the magnetic field generates an AC voltage and frequency in the outer conducting coil, which follows the speed of the flywheel.

To adjust the engine or fuel injection pump, one would need to adjust the tension of the speed-adjusting spring, also known as the speeder spring. This spring counteracts the force exerted by the flywheel on the spindle, and its pressure determines the speed of the engine necessary for the flyweights to maintain their central position. By changing the tension of this spring, the governed speed of the engine can be set.

The difference between marine and car engines

Marine engines and car engines have many differences that make them incompatible with each other.

Firstly, marine motors are designed to withstand a constantly wet environment. All parts of a marine engine are made of corrosion-resistant materials, which is not a common requirement for car engines, which are meant for dry environments.

Secondly, marine engines are heavy-duty, using as much low-end torque as possible to be at full throttle all the time to move through the water. In contrast, car engines have multiple gears and use only a portion of their horsepower to maintain a decent speed on the road.

Thirdly, marine engines have special screens on the alternator, distributor, and starter to extinguish internal sparks, preventing them from lighting gas fumes in the boat's engine area. These components are different from those in a car engine, and using a motor that doesn't have these screens can be dangerous.

Additionally, marine engines are used less often than car engines, which are typically used daily or several times a week. This difference in usage patterns means that marine motors are designed differently from car engines, which lose power and become weaker when left unused for extended periods.

Finally, marine engines are based on heavier-duty truck blocks with four-bolt main bearing support for the crankshaft, while car engines have just two. The camshaft profile in a marine engine is also ground to different specifications, maximising low-end torque instead of high RPM horsepower.

In summary, the significant differences between marine and car engines make them unsuitable to be interchanged, and a marine engine is required for a boat.

How to marinize a car engine

Marinizing a car engine involves converting it for marine use. This process typically requires several modifications to ensure the engine can withstand the harsh conditions of a marine environment. Here are the steps to marinize a car engine:

Understand the Differences:

Firstly, it's important to recognize the differences between car and marine engines. Marine engines are designed for a constantly wet environment, so all parts must be corrosion-resistant. They are also heavy-duty, as they operate at full throttle to move the boat through the water. This means the camshaft is built to utilize low-end torque rather than high RPM horsepower. Additionally, the alternator, distributor, and starter in a marine engine have special screens to prevent internal sparks from igniting gas fumes.

Select an Appropriate Engine:

When choosing a car engine for marinization, opt for one with a broad power-band, ideally from 500 to 5000 RPM. Car engines typically have a narrow power-band, as they rely on the transmission to adjust speed. However, marine transmissions usually have only one speed forward and one in reverse, so a broad power-band is essential to maintain power output.

Install a Flame Arrestor:

Install a flame arrestor on the carburetor to prevent gas fumes from igniting. Gas fumes are heavier than air and can fill the engine compartment. The flame arrestor will stop any flame caused by backfiring from igniting these fumes.

Use an Ignition-Free Alternator:

Use an alternator designed to prevent sparks. All alternators create sparks internally during operation, but ignition-free alternators have screens that dissipate heat, preventing the alternator's exterior from reaching ignition temperatures. Ensure that any other switches, pumps, or devices in the engine compartment are also ignition-free.

Implement a Keel-Cooler:

Cool the engine with a keel-cooler, a closed-circuit system that allows the use of antifreeze instead of raw water. Automobile engines are not built to withstand circulating saltwater, so the keel-cooler is crucial to prevent engine deterioration. Use non-ethylene glycol-based antifreeze to avoid clogging issues caused by jelly-like substances formed when ethylene glycol comes into contact with saltwater.

Consider Additional Modifications:

Depending on your specific application, you may need to make further modifications. For example, you may need to replace the camshaft, spark plugs, increase the oil reservoir size, or add a radiator. Consult with marine engineering experts or online forums for guidance on additional modifications specific to your engine and intended use.

Remember, marinizing a car engine is a complex process, and safety should always be a top priority. It is essential to thoroughly research and understand the unique requirements of your chosen engine and the marine environment in which it will operate.

The advantages of different types of governors

Governors are devices that control the speed of an engine automatically within prescribed limits. They are an essential component of all marine vessels, as they help control the speed of the propulsion plant being used on board. Governors are also fitted in auxiliary diesel engines, generators, and alternators.

There are several types of governors, each with its own advantages:

Mechanical Governors

Mechanical governors consist of weighted balls or flyweights that experience a centrifugal force when rotated by the action of the engine crankshaft. This centrifugal force is used to regulate the fuel supplied to the engine. They are advantageous because:

• They are cheap.
• They can be used when it is not necessary to maintain an exact speed.
• They are simple in construction and have few parts.

Hydraulic Governors

Hydraulic governors have a weighted assembly connected to a control valve, which directs hydraulic fluid to control the fuel racks and, consequently, the power or speed of the engine. They are commonly used in medium to large-size engines. Hydraulic governors are advantageous because:

• They have high power output.
• They have high accuracy and precision.
• They are highly efficient.
• Maintenance is easy.

Electro-Hydraulic Governors

Electro-hydraulic governors have a combination of a mechanical hydraulic backup and an electric governor. In case of failure of the electric governor, the unit can be manually controlled using the mechanical-hydraulic backup. The system has an electronic control valve that is connected to the armature in an electromagnetic field. Electro-hydraulic governors offer the following advantages:

• Faster response to load changes.
• Control functions can be easily built-in.
• The presence of indicators and controls allows for automation.
• They can be mounted remotely from the engine, reducing the need for governor drives.

Electronic Governors

Electronic governors provide engine speed adjustment from a no-load condition to a full load. They consist of a controller, an electromagnetic pickup, and an actuator. They are advantageous because:

• They offer faster responses to load changes.
• Control functions can be easily incorporated.
• The presence of indicators and controls enables automation.
• They can be mounted away from the engine, reducing the need for governor drives.

Frequently asked questions