Outboards for tender, traditional or eletric?


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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 the 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 litre of fuel and at a speed of 4 knots, 4-stroke engines have a range of at least one hour and 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 litre 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 decibel. 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 litres 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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