Electric boat
An electric boat is a powered watercraft driven by electric motors, which are powered by either on-board battery packs, solar panels or generators.
While a significant majority of water vessels are powered by diesel engines, with sail power and gasoline engines also popular, boats powered by electricity have been used for over 120 years. Electric boats were very popular from the 1880s until the 1920s, when the internal combustion engine became dominant. Since the energy crises of the 1970s, interest in electric boats has been increasing steadily, especially as more efficient solar cells have become available, for the first time making possible motorboats with a theoretically infinite cruise range like sailboats. The first practical solar boat was probably constructed in 1975 in England. The first electric sailboat to complete a round-the-world tour using only green technologies is EcoSailingProject.
One of the main benefit of shift to electric from fossil fuelled boats apart from environmental benefit is the low cost of operation. The spread between diesel and electric depends on fuel cost and grid cost in the respective region, but in a place like India this could be factor of ten.
History
Early
An early electric boat was developed by the German inventor Moritz von Jacobi in 1839 in St Petersburg, Russia. It was a boat which carried 14 passengers at. It was successfully demonstrated to Emperor Nicholas I of Russia on the Neva River.Golden Age
It took more than 30 years of battery and motor development before the electric boat became a practical proposition. This method of propulsion enjoyed something of a golden age from about 1880 to 1920, when gasoline-powered outboard motors became the dominant method. Gustave Trouvé, a French electrical engineer, patented a small electric motor in 1880. He initially suggested that the motor could power a set of paddle wheels to propel boats on the water, and later argued for the use of a propeller.An Austrian émigré to Britain, Anthony Reckenzaun, was instrumental in the development of the first practical electric boats. While working as an engineer for the Electrical Power Storage Company, he undertook much original and pioneering work on various forms of electric traction. In 1882 he designed the first significant electric launch driven by storage batteries, and named the boat Electricity. The boat had a steel hull. It was about long, with a beam of about and a draught of about. It was fitted with a diameter propeller. The batteries and electric equipment were hidden from view beneath the seating area, increasing the space available for the accommodation of passengers. The boats were used for leisure excursions up and down the River Thames and provided a very smooth, clean and quiet trip. The boat could run for six hours and operate at an average speed of 8 miles per hour.
Moritz Immisch established his company in 1882 in partnership with William Keppel, 7th Earl of Albemarle, specializing in the application of electric motors to transportation. The company employed Magnus Volk as a manager in the development of their electric launch department. After 12 months of experimental work starting in 1888 with a randan skiff, the firm commissioned the construction of hulls which they equipped with electrical apparatus. The world's first fleet of electric launches for hire, with a chain of electrical charging stations, was established along the River Thames in the 1880s. An 1893 pleasure map of the Thames shows eight "charging stations for electric launches" between Kew and Reading. The company built its headquarters on the island called Platt's Eyot.
From 1889 until just before the First World War the boating season and regattas saw the silent electric boats plying their way up and downstream.
The company's electric launches were widely used by the rich as a conveyance along the river. Grand ships were constructed of teak or mahogany and furnished luxuriously, with stained glass windows, silk curtains and velvet cushions. William Sargeant was commissioned by Immisch's company to build the Mary Gordon in 1898 for Leeds City Council for use on the Roundhay Park Lake – the boat still survives and is currently being restored. This 70-foot long luxury pleasure craft could carry up to 75 passengers in comfort. Launches were exported elsewhere – they were used in the Lake District and all over the world.
In the 1893 Chicago World Fair 55 launches developed from Anthony Reckenzaun's work carried more than a million passengers. Electric boats had an early period of popularity between around 1890 and 1920, before the emergence of the internal combustion engine drove them out of most applications.
Most of the electric boats of this era were small passenger boats on non-tidal waters at a time when the only power alternative was steam.
Decline
With the advent of the gasoline-powered outboard motor, the use of electric power on boats declined from the 1920s. However, in a few situations, the use of electric boats has persisted from the early 20th century to the present day. One of these is on the Königssee lake, near Berchtesgaden in south-eastern Germany. Here the lake is considered so environmentally sensitive that steam and motor boats have been prohibited since 1909. Instead the Bayerische Seenschifffahrt company and its predecessors have operated a fleet of electric launches to provide a public passenger service on the lake.The first electrically powered submarines were built in the 1890s, such as the Spanish Peral submarine, launched in 1888. Since then, electric power has been used almost exclusively for the powering of submarines underwater, although diesel was used for directly powering the propeller while on the surface until the development of diesel–electric transmission by the US Navy in 1928, in which the propeller was always powered by an electric motor, energy coming from batteries while submerged or diesel generator while surfaced.
The use of combined fuel and electric propulsion has gradually been extended over the years to the extent that some modern liners such as the Queen Mary 2 use only electric motors for the actual propulsion, powered by diesel and gas turbine engines. The advantages include being able to run the fuel engines at an optimal speed at all times and being able to mount the electric motor in a pod which may be rotated by 360° for increased manoeuvrability. Note that this is not actually an electric boat, but rather a variant of diesel–electric or turbine–electric propulsion, similar to the diesel or electric propulsion used on submarines since WWI.
Renaissance
The use of electricity alone to power boats stagnated apart from their outboard use as trolling motors until the Duffy Electric Boat Company of California started mass-producing small electric craft in 1968. It was not until 1982 that the Electric Boat Association was formed and solar powered boats started to emerge. To reduce friction and increase range, some boats use hydrofoils. The eWolf tugboat that launched in March 2024 has a 6.2 megawatt-hour main propulsion battery and two electric drives and is more powerful than the diesel tugboats at the port.Ferries
In 2023, electric-powered hybrid boats began to be widely adopted in India as a mode of urban transport, supplementing metro rail systems by utilizing rivers and other waterways. The Kochi Water Metro was the first project to be deployed with electric ferries. Its fleet consists of 78 electric boats, all built by Cochin Shipyard. Each vessel has a passenger capacity of around 100 and is capable of cruising at speeds of up to 10 knots. It uses 300 kW chargers which can charge the boat within 15 minutes.File:KWM Boat.jpg|thumb|right|Kochi water metro is an electric powered hybrid ferry in india build by Cochin Shipyard
Following the successful operation of the Kochi Water Metro, the model was replicated in other Indian cities. As of 2025, similar electric ferry services are operational in Patna and Ayodhya, with projects under implementation in a total of 21 Indian cities.
Incat Tasmania's China Zorrilla ferry is slated for use as a ferry in South America, carrying 2,100 people and 225 cars/trip. It offers a 40 megawatt-hour battery, in 12 battery arrays with 418 modules apiece, weighing 250 tonnes. The battery is air cooled with fans for each module. The batteries power eight axial-flow water jets driven by permanent magnet electric motors. The ship can operate 90 minutes between charges. Charging is planned to take 40 minutes.
Components
The main components of the drive system of any electrically powered boat are similar in all cases, and similar to the options available for any electric vehicle.Charger
Electric energy has to be obtained for the battery bank from some source like the sun.- A mains charger allows the boat to be charged from shore-side power when available. Shore-based power stations are subject to much stricter environmental controls than the average marine diesel or outboard motor. By purchasing green electricity it is possible to operate electric boats using sustainable or renewable energy. For large vessels, an onshore battery may be necessary to provide more short-term power than the grid can supply.
- Solar panels can be built into the boat in reasonable areas in the deck, cabin roof or as awnings. Some solar panels, or photovoltaic arrays, can be flexible enough to fit to slightly curved surfaces and can be ordered in unusual shapes and sizes. Nonetheless, the heavier, rigid mono-crystalline types are more efficient in terms of energy output per square meter. The efficiency of solar panels rapidly decreases when they are not pointed directly at the sun, so some way of tilting the arrays while under way is very advantageous.
- Towed generators are common on long-distance cruising yachts and can generate a lot of power when travelling under sail. If an electric boat has sails as well, and will be used in deep water, then a towed generator can help build up battery charge while sailing. Some electric power systems use the free-wheeling drive propeller to generate charge through the drive motor when sailing, but this system, including the design of the propeller and any gearing, cannot be optimised for both functions. It may be better locked off or feathered while the towed generator's more efficient turbine gathers energy.
- Wind turbines are common on cruising yachts and can be very well suited to electric boats. There are safety considerations regarding the spinning blades, especially in a strong wind. It is important that the boat is big enough that the turbine can be mounted out of the way of all passengers and crew under all circumstances, including when alongside a dock, a bank or a pier. It is also important that the boat is big enough and stable enough that the top hamper created by the turbine on its pole or mast does not compromise its stability in a strong wind or gale. Large enough wind generators could produce a completely wind-powered electric boat. No such boats are yet known although a few mechanical wind turbine powered boats exist.
- In hybrid electric boats, if a boat has an internal combustion engine anyway, then its alternator will provide significant charge when it is running. Two schemes are in use: the combustion engine and the electric motor are both coupled to the drive, or the combustion engine drives a generator only for charging the storage batteries.
An alternative to charging is changing batteries while in port. It offers the benefit of removing the need to wait for the recharging to complete before sailing. This approach has the potential to allow ships and ferries with tight schedules to be electrified as charging can be done in port with no time limitations.