As hybrid gas/electric cars such as Tesla and Prius have grown in popularity and become more practical options for mainstream consumers, boat manufacturers have begun to follow suit. Experienced boaters tend to have an appreciation for the natural aquatic environment and eco-system around them. From following the tides to co-existing with wildlife, being eco-conscious is deeply-ingrained in the boating lifestyle. New technologically-advanced boat models are now making hybrid gas/electric propulsion not only feasible but enjoyable.
In this guide we’ll take a look at some of the boat brands, models, engines, manufacturers and propulsion systems that are beginning to heat up the solar, electric/gas and alternative energy market in 2019 – bringing sustainability to the forefront of the marine industry.
How does a hybrid electric boat work?
A hybrid marine propulsion system is any combination of a combustion engine and an electric motor. Electricity can be produced by one or a combination of the following: a combustion engine generator, a wind generator, a towed water generator or solar panels. A purely electric solution with solar panels is enviable due to its zero carbon footprint and low operating costs and various takes on theses systems have been gaining traction on alternative energy vessels. Advances in both energy storage and solar panel technology have reduced costs and physical footprint making solar power propulsion systems more feasible for use on boats.
What are the benefits associated with hybrid and electric boats?
There are numerous benefits to electric motor propulsion including that it’s quieter, more efficient at lower speeds and less smelly. It’s also expected to lower overall costs of ownership by reducing or eliminating the needs for oil and transmission fluid changes, filter and impeller replacements and starter problems. There’s less to winterize too. Additionally, unlike diesel or gas engines, electric motors provide full torque instantly so boats get up on plane faster. Aftermarket conversions (which currently make up the lion’s share of the market) can use existing drive shafts and components so there is a cost-savings when re-powering.
Hybrid and electric boats and the current marine market
As mentioned, now that hybrid and pure electric propulsion systems have proliferated within the automotive industry, hybrid or electric boats are beginning to gain steam. Still, the marine world is a relatively small niche market that tends to follow rather than lead other industries in terms of innovation. Currently only 1.3% of boats today are integrating electric or hybrid propulsion. This slow adaption is partly due to the unique issues of boating. Boats have a different frequency and variance of use than cars and the market has many segments (ferries, sailboats, small high speed planers, large distance cruising yachts, etc.) where boats are used differently, making it hard to build one solution to fit all applications. However, a few companies are trying to change all that.
Power and auxiliary sailboats are typically propelled by inboard or outboard engines using diesel or gasoline fuel. A growing appeal has been placed on electric motors for these purposes – i.e. pure electric engines powered by large battery banks.
As with any new technology, there’s an adoption curve. The early adopters are the technologists, visionaries and tinkerers and they make up only about 15% of the market. In marine, these are distance sailors that need efficient sustainability and autonomy but they’re also ferries and water taxis that operate on bodies of water where combustion engines aren’t allowed. Then come the trailerable towboats, tenders and fishing boats as well as charter boats to fill the boating sweet spot of the 25-75 foot midrange power market.
What are the problems with marine hybrid and electric boating?
Because e-propulsion is in its infancy in the marine market, available solutions are few and they’re expensive. So far, most electric boats have been slow and small and had very restricted range but that is changing. There’s also the problem of infrastructure, which is the same for automotive: What is the range of these new vessels and where do they recharge? Just like a Tesla that you’d probably not take on a cross-country road trip, a boat needs charging stations that are close together and can “fuel” quickly.
The technology behind electric and hybrid boating
Use of brushless permanent magnet electric motors and advances in lithium ion battery technology have allowed for leaps to be made in the rush to marine electric. Lithium-ion batteries are half as heavy as lead-acid batteries and last three times as long, and advances in their effectiveness and stability have been significant.
German electric motor manufacturer, Torqeedo, teamed with BMW and “marinized” the automaker’s i3 and i8 Series batteries for use in a variety of boats. They added a rugged damping frame to minimize shock, a venting system to channel gasses safely and waterproofing to IP67 standard. The new batteries tout a 31% increase in capacity (energy density) over the previous similarly sized model and their footprint (roughly 5’ x 3’ x 6”) can be fitted into even the most compact engine spaces.
Serial and Parallel Hybrid Boats
Currently, two approaches are battling it out on the water – serial and parallel hybrids. The serial hybrid system integrates a range-extending generator. The engine drives the generator, which powers an electric motor connected to the driveshaft—there is no mechanical connection between the engine and the driveshaft. A parallel system has a direct mechanical connection between the engine and the driveshaft but also drives an additional electric motor that operates as a generator – on the same shaft.
Range-extending power regeneration may be accomplished by a free-spinning propeller, which is easy to do on a moving sailboat and can be accomplished by using only one engine at a time on a powerboat. UK motor manufacturer, Hybrid Marine, is offering a third option: a multimode system that combines the best of serial and parallel approaches with an arrangement of clutches and gears.
Fully Electric Marine Propulsion Systems
Torqeedo’s Deep Blue 100i motor is the first fully integrated inboard electric propulsion system, which is available in two versions – 2400 rpm for faster planing boats and 900 rpm for heavier displacement vessels up to 120 feet. The focus of the entire system, from helm to prop, is on safety and it’s expanded the target market in terms of size, speed and typical use of the vessel.
A comprehensive propulsion system is a complex combination of voltages and that makes things complicated on the water. For example, one inboard motor installation may include all of the following:
400 VDC for propulsion using automotive battery technology
110/240 VAC for hotel loads on AC
24 VDC for onboard electrics
12 VDC to “wake up” the larger batteries and generator/range extender
bi-directional switching between 24 and 400V networks
That’s a lot of technology to pack into space-sensitive hulls. It also adds complexity and cost.
Electric and hybrid marine engine manufacturers
Manufacturers who have focused on this market include Torqeedo based in Germany that subsidizes electric motor research. Another contender is Elco from Athens, New York, which, like Torqueedo, offers both inboard and outboard electric motors. Also, we mustn’t forget the classic Minn Kota trolling motors that have kept anglers emission-free for decades.
Other players in the motor market include the Finnish OceanVolt, Italian Diesel Center, American Electric Yacht, and British Hybrid Marine. California-based Electroprop sells pre-packaged 6 and 21 kW systems that boat builders can drop into their existing engine rooms. Swedish diesel engine giant, Volvo Penta, is promising a 2021 introduction of electric motors installed inline between their diesels and IPS pods, and is working with French catamaran builder, Fountaine Pajot, on a Lucia 40 sailing cat with hybrid power.
There are many players all searching for the killer app in marine alternative energy propulsion. It’s likely a few will survive while others are purchased or disappear in an increasingly competitive market.
Hybrid Solutions for Sailboats
Large sailboats are under auxiliary power often, especially when docking, anchoring or heading out on long windless passages. Distance cruising sailboats have pioneered solar power solutions for onboard energy needs for hotel loads such as refrigeration, A/C and lighting. However, propulsion has been a challenge. In 2010, production catamaran builder Lagoon, experimented with a diesel-electric design but there were challenges, primarily due to insufficient energy storage (battery) capabilities at the time. Lagoon builds the lion’s share of sailing catamarans in charter that are based in exotic locales where fuel is at a premium and a hybrid solution would be a game changer for the charter industry.
Inboard motor maker, OceanVolt, powers all manner of sailboats including JBoats sailing racers, Alerion luxury daysailers, and boats that are often seen in charter like the Dufour 382 and the Voyage 480 multihull. Meanwhile, Torqeedo’s Cruise outboard series includes models with a throttle control and a GPS-based battery-management system that continually reports the remaining range at variable speeds and requires only two 24-volt lithium-ion batteries. These outboards are well suited to smaller, lighter sailboats for close quarter maneuvering and short distance motoring but powerboats have benefited as well.
On the cutting edge, upscale sailing catamaran builder Gunboat launched Moonwave that is testing a hybrid electric power plant with a diesel generator backup. With BMW i8 batteries, Moonwave uses electricity for propulsion as well as their large hotel needs, which makes it hard to stay completely electric for long stretches of time.
Cutting-edge Concept Designs in Solar Boating
Fully-electric boats are making great progress but they’re still a small portion of the boating market. However, highly promoted concept designs are helping raise awareness of alternative energy solutions and one such advocate is Touranor SolarPlanet, a 102-foot catamaran with wave-piercing hulls. The futuristic Swiss SolarPlanet cost 15 million Euros when it was launched in 2010 and circumnavigated the globe in 585 days strictly on electric power generated by the 500 solar panels on her top deck. Although the design’s top speed was 14 knots, the average speed around the globe was 5 knots.
After that impressive feat, the boat was donated for research. Boats like this may be one-offs but they’re helping shine the spotlight on what can be accomplished in alternative energy propulsion and the direction that boating is taking.
Examples of Electric and Hybrid Boats
Due to advances in both motor design and battery technology, electric propulsion is reaching diverse segments of the boating market from small planing boats to large cruising yachts both power and sail. Some well-known boat builders have already dipped their toes into these alternative power waters.
Sleek and stylish, the Hinckley Dasher is a fully electric luxury yacht. Designed by Michael Peters, the 28-foot Hinckely Dasher was built from the ground up for electric propulsion. The resin-infused build mixes epoxy and carbon fiber with a synthetic core so the design weighs only 6,500 pounds. And weight is critical in electric mobility.
The Dasher is propelled by twin 40 kWh BMW i3 lithium ion batteries driving twin 80 hp straight shaft inboard motors. These are the same batteries used in the BMW i3 automobile and should last 9 years or 9,000 cycles. Expect to reach 23 knots of top speed or cruise at 8.5 knots. The maximum range at 20 knots will be 40 miles. Four hours is all that’s needed to charge from zero to full capacity, which is a little faster than a Tesla.
Soel Yachts, a Dutch company, builds solar and hybrid vessels including marine shuttles. The Soel Cat 12 from New Zealand looks like a pontoon boat with a solar array on the hardtop that carries up to16 passengers. Powered by twin 30 kW electric motors, the model can cruise at at eight knots for six hours solely on stored power. In sunshine, the cruising range is extended to 7.5 hours at eight knots. At six knots, the range goes to 24 hours (and approximately 150 nautical miles) so the boat can run at night when no energy is produced or stored. The maxium speed is 14 knots.
The Austrian Frauscher Mirage 740 Air was previously available with a Mercury 350-hp with stern drive but today can come with Torqeedo’s Deep Blue system that combines a high-rpm 100 kW brushless inboard motor with twin BMW i3 Series 40 kW batteries. The high-capacity lithium batteries are stacked one above the other in the engine compartment aft. The Frauscher is ideal for areas where recharging (with ordinary shore power) is available and its system can charge up to 75 percent capacity in less than 1.5 hours. Top speed is 24 mph at 2200 rpm. The range is approximately 20 miles. (Currently, the electric power package adds $120,000 to the Frauscher’s base price.)
Other Solar and Electric Boats
Other electric boats (some with solar arrays) include the Q Yachts Q30 tender and the Secret 33 water taxi. Duffy Boats has been building a line of electric leisure cruisers for the past 50 years. You’ll see many of these in rental service in tourist areas on cocktail cruises along with their main competitor, Lear.
ElectraCraft produces a line of electric pontoon boats, and Greenline Yachts out of Slovenia has a large selection of hybrid or electric drive models from 30 to 65 feet. The Greenline Hybrid 33 cruises up to 6 knots on electric power with six 1.3 kW panels on the hardtop and a lithium-ion battery bank, or at up to 15 knots using a 150 hp diesel.
Fuel Efficiency in Hybrid Boat Engines
Fuel-efficient combustion engines for boats that support hybrid power solutions
In a hybrid solution, there’s still a need for some form of combustion engine (for primary propulsion or as a generator). Increasingly, traditional diesel engine manufacturers have focused on improving the fuel efficiency of their engines in both inboard and outboard applications and they’ve become an ideal partner in hybrid approaches.
Volvo Penta just introduced their D4 and D6 diesel engines that have been reconfigured for a smaller size (for weight savings), lower emissions (for the environment) and better economy (for fuel-sipping efficiency). Meanwhile, outboard manufacturers like Evinrude and Yamaha have been building larger engines with more torque but better mileage. It seems the whole world is trying to ease up on their carbon footprint even if they don’t eliminate it altogether.
The future of hybrid and electric boating
The technology may be complicated and the adoption rate may still be below 2%, but change is happening at an accelerating pace as breakthroughs in battery expertise, motor design and lightweight hull-building materials are introduced. Fast, clean, quiet and price-effective electric, hybrid and solar boats will soon be within reach of boaters everywhere.