Outboard motors for dinghy, does traditional or electric win?


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For some time now, the question facing those who need to buy or change their tender engine has been this: do I go for the electric model or stay with the reliable internal combustion engine? Without examining ecological issues, we decided to cut our heads off and stick only to objective data. We compared four 4-stroke outboard models ranging from 2.3 to 3.5 hp and two electric ones that the manufacturer compares to conventional 4 hp. The result of our test can be found in a maxi comparison table.

THE WEIGHT. For boaters, the weight of the tender outboard is very important. How many times do you take it off the boat and lower it onto the tender? The less weight, the less effort. Here, the winners are the engines with the lowest power, the 2.3-hp Honda and the 2.5-hp Suzuki that weigh only 13.5 kg. But, surprise, the electric Torquedo weighs only 1.4 kg more, despite carrying the burden of a 915 kW lithium battery. Result: even

PERFORMANCE. As we have told you in order to compare the models with a minimum of homogeneity, we have chosen two electric models assimilated to traditional 4 hp. As for top speed performance, using a 3.30 dinghy in an inflatable nonrigid version with one person on board, there is no history. The more powerful 3.5-kilogram Tohatsu reaches nearly 8 knots of speed, while the Torquedo stops at 4.7 knots. But other models such as the Honda 2.3 also stops at the maximum speed’ of 4.6 knots, as does the 2.5 Suzuki. The surprise-but it was known, given the different power delivery between electric and internal combustion-is that with two people on board, electric models maintain virtually unchanged top speeds (just over 4 knots) while those of conventional models drop to virtually the same level. Moral: electric is less affected by loaded weight. Result: traditional wins

AUTONOMY. This is the key test of whether electric can compete with traditional. The result still gives an advantage to the 4-stroke engine, which, with only one liter of fuel (the full tank integrated), at a speed of about 4 knots has a range of at least an hour and a half or more than six miles. Fully charged electrics with an installed battery of about 1 kW (the standard one) hold out for an hour and then after 4 miles stop, completely discharged. The highest-powered 4-stroke model, the Tohatsu 3.5 hp manages to run at lower revolutions and with one liter of gasoline has a record range of more than two hours, about 8 miles. It should also be mentioned that if you reduce the power of the electric, decreasing the speed to two knots, the electric has a range of about 5 hours. So: just go slow and the electric makes up for the range deficit it has at full power. Result: traditional wins, but…

RECHARGE. Another important point of the test. If for a conventional outboard it is a matter of pouring fuel into the outboard tank for electrics you have to wait until you have recharged the battery. With a battery of about 1 kW (minimum recommended), full recharging occurs in 12 hours with a 220 volts and 12 times (at 45 watts) cigar lighter socket in about 20 hours. Of course, the battery disengages from the motor body to be recharged. As a reminder: electric obviously does not need engine oil, which in traditional needs to be checked and replaced every year. Result: even

The traditional has to do annual maintenance and winterization if you want to keep it in efficiency, the electric theoretically has no maintenance. Result: the electric wins

THE NOISE. An electric at most produces a “noise pollution” of 60/65 decibels, a noise that is not annoying at all. It is different when a traditional one rattles at 85 db like the Honda. Result: electric wins

COSTS. An electric outboard costs about twice as much as a conventional model. But there are no fuel costs. Doing the math and exaggerating, for a two-week cruise with several roadstead stops you can consume about 10 liters of gasoline that is a cost of 17 euros. Result: traditional wins

THE FINAL MORAL If you look only at cost, a conventional engine for the same performance is significantly cheaper. If you also look at pollution and have an ecological conscience then the choice today is not so obvious.


The first question people ask when they decide to buy or change their tender engine is: is it time to choose an electric model or is it better to buy a new combustion engine? Without considering environmental matters, we’ve decided to settle things once and for all and focus only on objective data. We’ve therefore compared four 4-stroke outboard models from 2.3 to 3.5 horsepower and two electric models that the manufacturer compares to traditional 4hp engines. You can find the result of our test in a large comparative table. Let’s discuss data.

WEIGHT For yachtsmen, the weight of a tender outboard is a very important factor. How many times is it taken down or installed on the tender? Less weight means less effort. In this respect, the winners are less powerful engines: the Honda 2.3 hp and the Suzuki 2.5hp engine that weight just 13.5 kg. But, surprise, the electric Torquedo model weights just 1.4 kg more, despite a lithium battery of 915 kW. Result: a tie.

PERFORMANCES As mentioned above, we’ve compared two electric models similar to traditional 4hp models. In terms of top speed, a 3.30-meter rib with inflatable keel and one passenger on board is certainly unrivalled. The most powerful engine, the Tohatsu (3.5 kg) delivers almost 8 knots while the Torquedo reaches just 4.7 knots. The Honda 2.3, too, delivers a top speed of 4.6 knots, like the Suzuki 2.5. The surprise–given the different power supply between electric and combustion engines–is that, with two passengers on board, electric models keep their top speed unchanged (little more than 4 knots) while the traditional engines’ ones go down to the same level. In conclusion, electric outboards are less affected by their load than traditional engines. As a result, traditional engines win.

RANGE This is the key test to see whether electric outboards can really compete with traditional counterparts. With just one liter of fuel and at a speed of 4 knots, 4-stroke engines have a range of at least one hour and a half (more than 6 nautical miles). With a 1 kW battery at full charge, electric outboards, instead, have a range of just one hour (4 nautical miles). The most powerful 4-stroke model – the Tohatsu 3.5 hp – features a lower rpm range and, with one liter of fuel, has a range of more than 2 hours ( about 8 miles). Moreover, at 2 knots, the electric model has a range of about 5 hours! So, a reduction in speed results into greater range. In conclusion, traditional outboards are better but ….

CHARGE This is another important aspect of our test. While traditional outboards need fuel to work, electric models depend on battery charge. With a battery of about 1 kW (recommended minimum power), full charge takes 12 hours with a 220 Volts charger and about 20 hours with a 12-Volt (45 W) cigarette lighter socket. Please remember that electric outboards, of course, don’t need engine oil. In traditional models, instead, the latter should be checked and replaced every year. Result: a tie.

MAINTENANCE While traditional engines require annual maintenance and winterizing, electric outboards need no maintenance. In this respect, the winner is the electric model

NOISE An electric outboard can produce a noise pollution of 60/65 decibels. This means that it is silent enough. Traditional engines, instead, can reach even 85 db (Honda, for example). So, electric models are better.

COSTS An electric outboard is about twice the price than a traditional model. Fuel costs are, however, not required. For a 2-week cruise with many stops, you can use about 10 liters of fuel for a cost of 17 euros. Result: the traditional engines win.

In conclusion: in terms of costs, a traditional engine (with the same performances) is certainly better than an electric outboard. But, if you consider pollution and you have an environmental awareness, the choice is not simple today.



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