Advantages of electric boating

Electric boating was not designed to replace boating with a fuel engine, but to offer a premium boating experience . Electric boating is clean, quiet and requires less maintenance.

Why electric boating?

Maintenance-free : Electric boating saves you dozens of hours of maintenance, making it easy in practice. You never have to do expensive annual maintenance, transport fuel or re-winterize your engine. This saves you time and money.

Surprisingly quiet: Fancy a relaxing trip? That's exactly what electric boating offers. It's the perfect choice for when you want to go fishing, for example, they can barely hear you coming. It's also ideal for a family trip without the loud engine interrupting your conversations.

Environmentally friendly : Zero greenhouse gas emissions and the engines will not leak oil or fuel.
Carefree transport: no stains or odors in your car when transporting fuel or engine.

No harmful exhaust fumes: A boat trip with family and friends without the dirty exhaust fumes. Choosing an electric motor means that no harmful substances are inhaled by you and your passengers.

Money saving: see the bottom of this article.

Is electric boating an option?

Yes, for most boats in the Netherlands it is even the best and most cost-effective option.

We explain that with most boats up to 7 meters you can sail a day at 7 kilometers per hour with only 3 kW of engine power and 4 kWh battery power . The range is then at least 30 kilometers, which is sufficient for most sailors. If you want to sail a heavy boat at high speed for a long time, electric sailing is only an option as a hybrid or in foil form. Hybrid sailing is done by placing an electric hybrid inboard engine with the existing engine, a second electric outboard engine next to a fuel outboard engine or by placing a pod engine . Hybrid is also possible by placing a generator so you can charge while sailing.

Electric motor sailing speed

Do you have a planing boat (that can 'skim' the water instead of just through it)? Then you can go faster than the hull speed. Otherwise, the maximum speed is the hull speed . You calculate the hull speed by multiplying the square root of the waterline of the ship in meters by 4.5. Waterline = the part of the boat length that touches the water. If you don't know the water length, take the length of the boat and subtract half a meter for convenience.
So at a waterline of:

8 meters you reach 13 kilometers per hour;

7 meters you reach 12 kilometers per hour;

6 meters you reach 11 kilometers per hour;

5 meters you reach 10 kilometers per hour;

4 meters you reach 9 kilometers per hour;

3 meters you reach 8 kilometers per hour.

Cruising speed is the economic speed at which a boat can move as efficiently as possible. This speed is always a trade-off between speed and fuel consumption. The economic speed is 70% of the hull speed, so at:

8 meters = 9 kilometers per hour;

7 meters = 8 kilometers per hour;

6 meters = 8 kilometers per hour;

5 meters = 7 kilometers per hour;

4 meters = 6 kilometers per hour;

3 meters = 6 kilometers per hour.

For the hull speed you need as much as 3 times as much power as the economic speed. Then the battery is quickly empty and you only reach a 30% higher speed.
So in almost all cases you will sail between 6 and 9 kilometers per hour with a (non-planing) boat of 4 to 8 meters. The top speed is usually 30% higher but the consumption is then 300% higher.
It may be wise to get a motor that can reach the hull speed because you may have to deal with headwind or river current of 5 kilometers per hour. Or when you have battery capacity left and just want to sail faster.
More power often has no effect. We therefore recommend 2 to 3 times the power required for the economic cruising speed for the engine power.

Electric fast sailing

Then an optimized hull shape is important. Like the Pure 585 from Pure Boating one of the striking features of this innovative hull shape is the efficiency in the speed range of 12 to 20 kilometers per hour, ideal for moments when you don't want to sail too fast, but still want to move forward. Or the Marinaut 540 sloop reaches a speed of up to 15 kilometers per hour with a 6kW Electric outboard motor .

Depending on the length of the waterline, the boat will barely exceed hull speed no matter how much power is added.

Fast boats can climb over it, and from about 25 kilometers per hour they start sailing nicely and efficiently again, because they start planing. Fast boats are sometimes not nice boats when sailing slower, especially in the area between hull speed and planing.

A very efficient hull shape needs little power, and goes almost unnoticed over the hull speed. No stern wave, with annoying wave action, no noise and before you know it you are gliding smoothly past everyone, electrically! A very satisfying feeling, which you really have to experience yourself to really understand.

"Cheat hull speed source: PureBoating.nl, edited".

Required engine and battery power

The amount of engine and battery power required depends on the total weight.

Take the weight of the boat (many sloops weigh between 400 and 1,000 kilograms) and add 450 kilograms for the engine, battery and 4 adults.

Multiply the total weight by 1.1 and you have the required power. So with a total weight of 850 kilograms you need 935 Watts (0.94 kW) of power for economical speed . For hull speed you need 3 times as much power, for this you multiply the total weight by 3.3. For a total weight of 850 kilograms you need 2.8 kW of power. For salt water you need 25% extra power so in the example of 2.8 kW it becomes 3.5 kW.
For the power of your boat, you can usually suffice with 2 x the power for economic speed . If you want to occasionally reach the hull speed or if you sail in areas with a lot of current, you can take 3x the power, for example. In a calm lake and short sailing distance, 1x the power for economic speed can also be sufficient. If you take more than 3x the power, it has no effect. The boat will not sail any faster.
Even if you use too little power you will still move forward, see this video ; a 12.5 ton sailing boat sails 5 kilometers per hour with a 1 kW engine.
In practice, you usually only sail at 20 to 30 percent of the power (source: Epco Ongering Vaartesten.nl).

Electric motors have 4 times as much thrust as petrol engines, so a 1 hp electric motor is equivalent to a 4 hp petrol engine. 1 LBS of thrust can propel 10 to 20 kilograms.

To determine the correct power of an electric motor for a boat, it is not enough to convert the horsepower into kW (factor 1.7). An important reason is that the powers are measured in different ways. The effect of the engine on a boat is not so much determined by the absorbed power in kW or the shaft power in hp, but by the thrust . So what power does the propeller that rotates in the water deliver to the boat? An electric motor has less loss, partly due to the higher torque over the entire speed range. This allows a larger, more efficient propeller to be used with more thrust. This makes towing or moving objects and people child's play.
For example, a 6 hp (4.5 kW) combustion engine is comparable to a 3 kW electric motor from Torqeedo (factor 2.5). Of the gross input power, the net power on the shaft is equal to the net thrust on the propeller. More details .

If you want to convert the power of an electric motor to hp, you can calculate with a factor of 1.7 to 2.5. A 6kW electric boat motor is then comparable to a 10 hp (propulsion power) to 15 hp (thrust) fuel engine.

Another reason that many boats are equipped with larger combustion engines than necessary to get them to maximum speed. One reason is because it then “runs more quietly” at lower speeds. An electric motor will always run more quietly.

How long and how far can I sail?

That depends on the weight, speed and battery capacity. The consumption per hour is equal to the number of kW needed for the desired speed . With a total weight of 850 kilograms and economic sailing speed that is 0.94 kW per hour.

Do you want to sail 6 hours non-stop at economical speed, with a total weight of 850 kilograms? Then you need a battery of 850 * 1.1 * 6 = 5,610 kWh.

What distances and sailing time do you cover in a day?

- Assume a sailing time of 2 to 3 hours for short trips within a lake area or in the city with a distance of up to 20 km.
- Assume a sailing time of 3 to 4 hours for day trips within a region with a distance of up to 40 km. The average water sports enthusiast sails for three to four hours a day (source: Epco Ongering Vaartesten.nl).
- Assume a sailing time of 5 to 6 hours for longer distance holiday trips, up to 60 km per day.
- Assume a sailing time of 7 to 8 hours for long sailing days with a distance of up to 80 km (Aquatec, 2019).

In the calculation we assume a distance of 30 kilometers at a speed of 8 kilometers per hour = 4 hours of non-stop sailing . In practice you sail longer because you do not always sail at full speed and sometimes you also stand still.

How much battery capacity do I need for different total weights?

450 kilograms: 2.0 kWh battery capacity

850 kilograms: 3.7 kWh battery capacity

1000 kilograms: 4.4 kWh battery capacity

1200 kilograms: 5.2 kWh battery capacity

1500 kilograms: 6.5 kWh battery capacity

2000 kilograms: 8.7 kWh battery capacity

3000 kilograms: 13.1 kWh battery capacity

A Lithium lifepo4 battery is the best battery, it is also 2 to 3 times lighter and smaller than a Lead AGM battery. The price is 2 to 3 times as high, the lifespan is also 3 times as long. As for the lifespan, you can also discharge 400 times with Lead AGM , so that is more than enough for a boat. Preferably connect Lead AGM battery continuously to the (trickle) battery charger.

In summary

For many boats, approximately 5 metres long and with a total weight of 850 kilograms, a 3kW engine and a 4kWh battery are sufficient for a sailing day of 30 kilometres at a speed of 7 kilometres per hour.

To reach the hull speed of 10 kilometers per hour you need 2.8 kW. So a 3 kW engine and a 4 kWh battery will be sufficient. If you sail slower or with fewer adults, you can sail longer and further on a sailing day. The investment including battery is already equivalent to a fuel outboard engine. Without maintenance costs and lower fuel costs, the investment for an electric engine is already lower.

Calculate it in detail yourself for your boat. Based on the length of your boat and the weight you will immediately see your:

Economic speed;

Hull speed;

Power for hull speed;

Power for economic speed;

Required battery power for desired range at economical speed;

and the Non-stop sailing time at the desired sailing range.

Realize that every boat is different. A slim, light boat, for example, sails more efficiently than a wide and heavy one. The sailing area is also important. When sailing on sheltered water and for shorter distances, a lighter engine can be used than when sailing on open water.

We are also happy to provide advice on this, preferably via chat!

Product advice

For boats

0.7 kW electric outboard motor
ePropulsion Spirit 1 kW Plus Tiller Electric outboard motor ePropulsion Spirit 1 kW Evo (Plus) with 1.3 kWh battery Electric outboard motor 48V.
up to 950 kilograms: ePropulsion Navy 3.0 Evo 3 kW Electric outboard motor 48V
ePropulsion Navy 6.0 Evo 6kW Electric Outboard Motor 48VePropulsion Pod Drive 6.0 Evo Electric Pod Motor 6 kW 48V
Waterworld 4.0 i 7.5 i 10.0 i 20.0 i electric inboard motor 4 - 20 kW 48V or a pod motor as a (hybrid) alternative: ePropulsion Pod Drive 3.0 Evo electric Pod motor 3 kW 48V or ePropulsion Pod Drive 6.0 Evo electric pod motor 6 kW 48V

For heavier boats please contact us.

Money saving

The total investment is currently barely higher than a 10 to 20 hp fuel engine. Based on a consumption of 2 liters per hour, the consumption costs for the fuel engine are at 2 euros per liter; 4 euros per hour and rounded 15 euros per day. Save 150 euros per year when sailing 10 days a year.
With the electric motor, the electricity costs are only 2.2 kW and 0.55 euros based on 0.25 KwH.
A whole day of sailing for less than a euro! Save on maintenance costs too. A fuel engine needs an annual minor service (110 euros) and sometimes a major service (200 euros). This also saves you around 150 euros per year. So you save 300 euros in the first year.

Charging with solar panels

Ideal if you don't have a power outlet on the boat. We can supply foldable solar panels that you can put on the boat. While sailing, you put the solar panels in the boat.

1). 100 Wp: 100*70 centimeters for 12 volt motor. In a maximum of 3 days (in the sailing season) you can charge 1 kWh.

2). 200 Wp: 200 * 140 centimeters for 12 or 24 volt motor. In a maximum of 3 days you can charge 2 kWh or 4 kWh in 6 days.

3). 400 Wp: 400*140 centimeters for 12, 24 or 48 volt motor. In a maximum of 3 days you can charge 4 kWh or 8 kWh in 6 days.

Charging at home

We can also supply portable 1 kWh batteries that you can charge at home if you cannot charge at the boat.

Subsidy

The electric boat engines and lithium batteries are eligible for Environmental Investment Deduction and Arbitrary Depreciation of Environmental Investments for vessels that are used commercially. That saves up to 36%!