Electric vs. combustion engine boats; (all you need to know)

This piece hopes to shed some light on some of these questions, as well as highlight the progress made over the years, resulting in boats like the Candela C-8.

1. Speed

As of 2022, the most potent outboard electric motor available is the Vision Marine E-Motion 180E 134kw electric motor, while inboard motors can range from small to large commercial sizes. The E-motion 134kw motor is the equivalent of a 180hp combustion outboard like this one from Yamaha. However, many factors can play into the speed of a boat, from the hull shape to the weight of the passengers onboard. Currently, when thinking about powerboats, there are generally more high-power options in combustion, but this trend is now shifting. 

Firstly, electric outboards are becoming more efficient and more powerful yearly, with options like the Evoy Hurricane 300+kw becoming available in the next couple of years. Furthermore, new and innovative boat design has created the need for less power necessary to reach the same speeds. Take for example, the Candela C-8. The C-8 uses a mere 55kw pod motor in order to achieve speeds up to 30 knots, equivalent to combustion boats like the Vanguard VanDutch 40 which uses around 600kw to achieve the same speed. The C-8 reaches this level of efficiency by using a combination of lightweight materials, aerodynamic design, and hydrofoil technology, allowing for less water friction and an overall more energy-efficient design.

2. Emissions

One major benefit of electric boats is the achievement of 0 direct emissions. This means that when operating an electric boat, there are no environmentally harmful gasses released as a result, creating a more enjoyable experience for the user while also being beneficial for the environment. Equivalently, a traditional combustion outboard motor can produce nearly 10,000 lbs of carbon emissions per year given light to moderate use. Though taking more resources to produce the lithium-ion batteries needed to power an electric boat, emissions savings can be seen within 6 months of usage when compared to a standard combustion engine. 

This can be important for conscious boat usage, but also for restrictions. Some lakes and marine areas now put limitations on emissions in order to preserve the immediate environment, thus eliminating many gas-powered options. Electric boats thus provide an opportunity to take advantage of otherwise inaccessible areas on the water.

3. Noise Pollution

A major benefit that comes with electric motors is a less noisy experience. In a combustion engine boat, the motor creates increasingly more sound as more power is demanded from the engine. This not only makes for a less practical experience when trying to have a conversation out on the water, but can also be a difficulty in restricted areas where noise pollution is kept to a minimum. In the Swiss Alps lakes, boats louder than 72 db are often restricted in where they can go, which is difficult when a combustion engine boat will go to 80db at cruising speeds. This is due to various negative effects the noise brings to the immediate natural environment, creating problems for the natural ecosystems and as a result, the surrounding areas.

The benefit that electric motors have is that they require fewer moving parts and, more importantly, no combustion. Electric boats can range from traditional outboard-style motors with a standard crankshaft going to the propeller to inboard motors that use direct drive systems which are generally more efficient and quieter. This results in boats in which you can comfortably have a conversation on with the added benefit of less vibration brought by electric motors. 

In some cases, as in the case of the C-8, hydrofoil technology allows for further reduction of noise pollution as the boat does not plow through the waves in a way a planing boat would, therefore creating an even more comfortable experience in a variety of sea conditions. 

4. Water Pollution

Combustion engine boats are more likely to create detrimental damage to the natural environment as a result of the chemicals they release into the water. Much of the time, this is due to poor maintenance, though even well cared for engines produce significant traces of pollution over time. Unburned fuel from motors are sometimes discharged from boats into the water as a way to prevent flooding in the engine. Though technology has allowed combustion engines to become more efficient at using fuel, discharge still occurs. Furthermore, winterization products such as antifreeze used in engines also contain harsh chemicals which severely damage the immediate environment. 

Electric boats require hull maintenance and regular cleaning just as combustion engine boats do, however, pollution is drastically decreased due to overall less synthetic materials needed that could end up in the water. Since electric motors do not require fuel or oil for propulsion, it is less likely that poor maintenance will cause major damage to environmental systems. 

5. Driving Regulations

In the past, electric-driven boats have been seen as low-speed cruising crafts perfect for lake shores where wake had been restricted. However, with more advanced technology and better performance, electric boats see much of the same wake restrictions as their conventional counterparts. However, in marine protected areas, electric boats are generally less restricted than combustion engine boats given their lower emissions and overall quieter operation. As technology advances, marine associations are re-evaluating restrictions and rules which currently affect the large majority of boats. 

6. Acquisition, Maintenance, And Operation Costs

Currently, the acquisition cost of an electric boat is more than an equivalent conventional powerboat. This is due to the fact that the technology used in electric boat propulsion is still new and thus not as cheap to produce as a current conventional boat. Currently, more electric outboards are becoming available on the market with built-in batteries, however, these often lack the range desired by many customers.
However, it is after the initial acquisition cost that the electric boat begins to shine. Operating an electric boat, in the large majority of cases, is cheaper than a combustion-powered boat. Despite fuel being more energy dense than lithium-ion batteries which are standard in electric boats, a majority of the energy produced is lost to sound, vibration and heat. Electric motors, alternatively, are much more efficient and thus can go a surprisingly long distance even on smaller batteries. Furthermore, the cost of fuel is much higher than the cost of electricity, therefore charging an electric boat to full charge costs a significant amount less than refueling an equivalent combustion engine boat.

Electric boats also have an advantage in maintenance. Every boat must have the body and propeller regularly maintained in order to protect against barnacles, corrosion, rust and more. In combustion engine boats, many service points are available due to the various chemicals and moving parts needed for operation. Given that most boat owners do not use their boat on a regular basis, oftentimes this means that one must check their boat before they leave the marina for bad fuel, clogged systems, good oil levels, rust and corrosion, etc. Regular boat maintenance on a monthly basis can help protect against aging and problems, however this does end in a high number of expenses over time. In the engine alone, one can expect worn spark plugs, clogged air filters, worn drive belts and lubricant replacements in order to maintain proper working order. 

An electric boat in comparison tends to have far fewer service points due to having far fewer moving parts. This is due to the lack of transmission and fuel system. It is still however important to check seals and exposed wire housing ever so often as sea air and sun exposure can sometimes cause wire housings to break down, leaving wires exposed which can rust. In order to care for this, regular washing and cleaning is key, as it is with all watercraft. 

7. Charging And Refuelling Time

Standard marina pumps can refuel at a rate of around 132 liters per minute. In a standard daycraft, such as a Finnmaster t-8, this would translate into a 2-minute refueling time. This requires some care and precaution, however, as fuel leakage can be dangerous for both the boat and the individuals onboard. Thus, a few minutes of preparation are often necessary in order to prevent any potential problems when refueling. 

Alternatively, an electric boat like the Candela C-8 takes around 2 hours to fully charge. Electric boats in general have significantly decreased in charge time over the past few years as faster chargers and more efficient batteries have come on the market. Though taking a lot longer than a combustion engine boat, an electric boat has the benefit of easy access to electricity in most marinas or docks. As most docked boats require electricity for various systems onboard while engines are off, electric boats benefit from being able to charge at the dock without needing to find a refuelling station. This means that after a day of cruising and exploring, one can simply leave the boat to charge at the dock and be at ease the next time they think to use the boat as it will always be fully charged. 

8. Range

Range depends on many factors including weight, engine size, fuel efficiency, sea conditions, etc. When comparing the range of similarly classed boats, speed can be a strong factor. This is because boats can have much longer ranges at slow speeds while higher speeds see a significant decrease in range.

At cruising speed (20-30 knots), a 27-foot-long day craft is likely to do around 125 nautical miles of range. In comparison, electric boats tend to have a much lower range as a result of the heavy batteries needed to power the vessel, resulting typically in a range of around 30 nautical miles. There are exceptions, however, like the Candela C-8 which takes advantage of hydrofoil technology and modern construction in order to achieve cruising speeds with a range of over 50 nautical miles. Though a combustion engine boat has more than double the range, 50 nautical miles is still more than enough for a day out on the water or even an overnight trip.

9. Weight

Electric boats are unsurprisingly much heavier than combustion engine boats of the same size. Though much weight is saved by a reduction in moving parts, the requirement for a battery means that electric boats tend to be heavier than their combustion driven counterparts. This is significant when thinking about towing requirements as well as how the boat is operated in water. In the case of combustion engine boats, as fuel levels decrease, so can the behavior of the boat.  A lighter boat can be easier to maneuver, while also being more difficult to manage in rough sea conditions at high speeds. Alternatively, electric boats have a more consistent weight, however given current technology, this can lead to slower speeds and a shorter range. 

Candela has found a unique solution to this problem. By combining hydrofoiling technology with electrification, Candela’s line of boats are able to overcome the difficulties that standard electric boats face, making them the most efficient power boats to date. 

10. Operation

A major benefit of electric boats is the ease of operations when compared to combustion engine boats. Standard combustion engines require warming up, lubrication, and sometimes even a choke in order to start. This could sometimes be a lengthy process depending on the age and condition of the engine. Electric motors simply need a switch or a button in order to start. Even further, electric boats are more user-friendly to both experienced captains and complete beginners. With a lack of transmission, electric boats can operate on a simple forward-back shifter, as opposed to a traditional transmission that requires more patience, practice, and most significantly, maintenance. In many electric boats, including the Candela C-8, one can even calculate range, power consumption and more which are not so easily accessible in combustion engine boats. 

11. Efficiency And Energy Consumption

For many years, boat engines have become increasingly efficient, resulting in longer range, less vibration and more power. Today’s modern engines have up to 35% efficiency, with 14% of energy driving the propeller itself. The infographic below shows where much of the energy is lost, including friction, heat and sound. Since gasoline is energy dense, this level of efficiency is often not noticed by boat users, though raising fuel prices and new alternatives make this more obvious now than it was in the past. 

Electric boats offer a strong offering in this sector. Since electric boats often have a direct drive system where energy from the battery is converted almost directly to propulsion, energy efficiency is greatly increased up to 90%+, resulting in less energy lost in the propulsion process as well as less cost per nautical mile.

 Candela C-8 takes this one step further. By streamlining and focusing on each component of the vessel, the C-8 sees an 80% reduction in friction, an 79% percent efficiency increase in propulsion, and an overall energy efficiency of 72.3%. As a result, the C-8 is the quietest, smoothest and most efficient powerboat ever. 

12. Stability

Stability is determined by everything from the shape of the hull to the weight of equipment, fuel, stores, and load. These forces can also be adversely affected by the prevailing weather conditions and sea state. One significant factor is the weight distribution, where weight placed in a certain part of the hull can cause the boat to lean to that side. Many sailboats and some powerboats have a keel that extends down from the middle of the hull in order to maintain stability in a variety of conditions. In combustion-driven boats, as the fuel level decreases, so does the level of stability due to fuel having more space to move around in the tank as well as a weaker weight towards the middle of the hull (where fuel tanks are commonly placed) to maintain a strong center of gravity. This results in boats at times being unpredictable in some weather conditions, which can be dangerous for even the most experienced captains. 

A benefit brought by electric boats is the battery pack which is generally placed at the boat’s center of gravity. Though the battery does lose weight as it discharges, it does so at a miniscule rate compared to a common fuel tank. Thus, electric boats tend to be more reliable in performance as compared to a conventional boat. Furthermore, it is no surprise that electric batteries are heavy as compared to equivalent fuel counterparts, but there are benefits to the added weight. In this case, the strong center of gravity provided by the battery can allow some motorboats to forego the need for a keel, thus allowing electric boats to operate in sometimes shallower waters than conventional boats.

Conclusion

To wrap things up, electric boats are currently on their way to become leaders in all areas of interest to boat owners and the marine transport industry. While combustion driven boats are still cheaper, easier to find parts for and still have overall longer range, the paradigm is shifting quickly. Electric boats go beyond the motor, as seen in the C-8. They represent a vision of the future, improving and perfecting the boat as we know it.