Diesel developments


Although the basic core of today’s modern marine diesel engine remains essentially the same, the controls, fuel systems and accessories have changed greatly. With the advent of common rail fuel injection and its associated computer controls the lowly iron wind has entered the computer age. Environmental Protection Agency (EPA) requirements for cleaner burning engines have also driven the new computer technology in an effort to reduce emissions.

Common rail fuel delivery came of age back in the early 2000s. Common rail is primarily used on engines larger than 100 hp. With this system, fuel is delivered to a common rail or pipe, to all the injectors at the same time. The electronic injectors are then controlled by an electronic control unit (ECU), a computer that will use data from things such as throttle position, engine temperature, and engine load to determine just the right amount of fuel to send to the cylinder. Not only can it control the amount of fuel, but also how that fuel is delivered to the combustion chamber. The fuel can be delivered in varying amounts and bursts lasting microseconds that will make sure all the fuel is burned as efficiently as possible. Part of the EPA’s National Clean Diesel Campaign, the proposed rule for marine engines will require a 90 percent reduction in particulate matter (PM) emissions, 80 percent reduction in nitrogen oxides, and additional reductions in hydrocarbons, carbon monoxide and air toxins. The proposed marine reductions occur in two phases, with implementation of the most stringent standards slated to begin in 2014. Proper controls of the injection system are a key part of meeting these tough new standards.

Manufacturers of smaller diesel propulsion engines and gensets for voyaging boats, like these from Westerbeke, are offering electronic controls as an option.

Computer transmission control

Computer controls are not limited to the fuel systems alone. Marine transmissions and drive units are now becoming part of the overall system packages, all being controlled by the engine ECU and helm control. With full control over the engine and transmission a vessel is now easier to operate at low speeds when docking or maneuvering. This, of course, is when the owner or captain needs the most control. The days of pulling a control or flipping a switch to operate a manual bypass trolling valve are long gone. With today’s electronic controls, the transmissions are automatically handled from the helm control when in low speed range. Electronic variable valves allow the transmission to slip as needed to reduce propeller speed at low speeds and to reduce slip as the vessel is throttled up, giving instant control over speed and torque. The introduction and popularity of pod type drives such as Volvo Penta IPS and Cummins Zeus further adds to maneuverability in tight locations. Even standard drive systems are seeing the traditional lever control being replaced with a joystick control. At low speeds the operator can use the joystick to control twin engines and transmissions with one simple intuitive control, increasing maneuverability and safety. At higher speeds traditional wheel steering and rudders are used to control vessel direction while electronic controls operate engine speed.

For smaller sailboat auxiliaries the changes have not been so great. Since most engines less than 100 hp are exempt from the EPA requirements, not much has been done with common rail injection or electronic fuel control. This doesn’t mean these engines are being completely left out of this new revolution in electronic controls, however. Some manufactures are starting to work with unit injectors. These are similar to the traditional single injector, but electronic control is added to improve efficiency. Additionally, many smaller engines now offer an option for electronic controls and displays. Some offer NMEA 2000 integration as well, allowing you to have your engine information displayed on your chartplotter. Less obvious developments include more horsepower with less weight and a reduced engine size. For the sail voyager this means better performance under sail as well as under power. Greater fuel efficiency means less fuel needs to be carried, reducing weight and increasing range. Most engine manufactures are also adding larger alternators for battery charging.

Hybrid systems?

Although there has been a lot of talk of hybrid systems like those that have become popular in cars, these systems have yet to have a big impact in boats. Although hybrids offer some improved efficiency for boats, it is not likely we will see the gains cars have seen — unlike boats, cars can recover some lost energy when braking. For powerboats the fuel efficiencies come from operating the diesel engine at an optimum steady rpm that maximizes fuel efficiency while varying the speed of the electric motor for vessel speed. For sailboats the efficiencies come from being able to allow the propeller to work backwards and turn the electric motor as a generator while sailing. This places drag on the vessel under sail, but the increased fuel range could more than make up for this. Another big asset to the hybrid is quieter operation. Being able to run a generating engine at a lower, steady rpm can reduce noise and vibration.

What does the future hold for the marine diesel? We’re likely to see a greater integration with computers and communication systems. Some manufacturers are looking into systems that would allow an owner experiencing engine problems to upload engine data real time via a satellite link to receive live trouble-shooting help even while at sea. Controls and displays will continue to follow the “fly by wire” protocol. Joysticks are likely to become common on boats of all types. Drive pods like those now seen in large shipping vessels are likely to find their way into our pleasure craft giving us even greater control and fuel efficiency. As the automotive industry pushes improvements in batteries and hybrid drives we will find these will prove more useful in our boats.

Capt. Wayne Canning lives on his Irwin 40 VAYU, in Wilmington N.C. Canning is a full-time marine surveyor, freelance writer, and consultant/project manager on major repairs. Canning also runs websites for other marine professionals, and those restoring project boats. Visit www.4ABetterBoat.com and www.projectboat.info for more information.

By Ocean Navigator