From Internal Combustion to Electric Propulsion by Walt White
Introduction
As the global focus turns to cleaner, greener energy sources, converting yachts from internal combustion engines (ICE) to electric propulsion has become increasingly popular. Among the voltage options available, 48V DC systems offer numerous advantages, including safety, availability, and cost-effectiveness. In this article, we will explore the benefits of opting for a 48V DC system when transitioning a yacht from diesel or gas to electric propulsion.
Creating an Optimal Electric Propulsion Experience
Making a user experience with electric propulsion involves several key factors:
- Smooth and quiet operation
- Ease of use
- Reliable performance
- Efficient energy management
- Easy maintenance
- Clear monitoring and display
- Quick and efficient charging
- Safety features
- Safety and Regulatory Advantages of 48V DC Systems
Electrical Safety on Boats:
Compliance with marine electrical standards, such as those set by the American Boat and Yacht Council (ABYC), is crucial for safety. Systems using voltages higher than 48V DC often involve additional safety and regulatory requirements. By selecting a 48V DC system, the voltage stays below the 60V DC limit, bypassing these extra regulations and ensuring a “touch-safe” environment on board.
Compatibility with Electrical Equipment
First let’s look at a list of typical “house loads” on a yacht (these are all the electrical loads on board, except for the electric motor used for propulsion).
Grouped into AC and DC loads, with approximate power consumption for each:
DC Loads:
- Interior and exterior lighting (LED) – 1-3W per light
- Navigation equipment (chartplotter, GPS, radar, etc.) – 10-50W
- Communication equipment (VHF radio, AIS, satellite phone, etc.) – 5-25W
- Water pumps (freshwater, bilge, shower sump, etc.) – 10-50W
- Refrigeration and freezer units – 40-200W
- Marine electronics and instruments (depth sounder, wind instruments, autopilot, etc.) – 5-50W
- Battery charging systems (for main and auxiliary batteries) – 10-50A
- Electric toilets and holding tank pumps – 10-50W
- Anchor windlass – 500-2000W
- Bow and/or stern thrusters – 2-8kW
- Electric winches and sail handling equipment – 100-800W
- Ventilation fans and blowers – 10-50W
- Security and monitoring systems (alarms, cameras, etc.) – 5-20W
AC Loads:
- Entertainment systems (TV, stereo, speakers, etc.) – 50-300W
- Galley appliances (microwave, stove, oven, etc.) – 500-1800W
- Air conditioning and heating systems – 500W-10kW
- Inverter and/or generator for AC power supply – 50-2000W (depending on the size of the inverter/generator)
- Shore power connections and charging systems – 500-2000W
- Electric dinghy davit or crane system – 500-2000W
- Watermakers and water purification systems – 300-2000W
One significant advantage of a 48V DC system is the broad range of compatible electrical equipment available for yacht re-powering. Retrofitting or replacing house loads with a 48V DC system is generally a straightforward task for marine electrical technicians, and often even for boat owners, as it avoids the complexities associated with high-voltage systems.
Inboard motors for propulsion, like the Newport-25, operate on 48V DC power, eliminating the need for any high-voltage systems on board. Other essential components such as power inverters, battery chargers, and solar chargers are also more readily available and affordable for 48V DC systems compared to higher voltage alternatives.
Simplified and Cost-Effective Power Conversion
Converting power from the main battery to support various onboard loads is a crucial aspect of re-powering a yacht with an electric propulsion system. With a 48V DC system, it is simpler and more cost-effective to convert power to the commonly used 12V DC for house loads, such as pumps, lights, cockpit instruments, and radios. This conversion can be easily achieved using a DC-DC converter that steps down the voltage from 48V to 12V DC. With the exception of the windlass and bow thrusters, high-power 12V DC systems can be easily accommodated with this setup.
In Summary:
Choosing a 48V DC system for re-powering a yacht from diesel or gas to electric propulsion offers numerous benefits, such as enhanced safety, compatibility with a wide range of equipment, and cost-effective power conversion. By staying within the “touch-safe” range and avoiding additional regulatory requirements, yacht owners can experience a seamless transition to cleaner and more sustainable electric propulsion without compromising on performance or convenience.
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