These motors are part of the test:
(click to see the detailed individual ratings)
Whether as a drive for the dinghy or as a lull pusher - outboards are used on many sailing boats. Depending on the purpose and sailing area, there is a choice between different sizes. As dinghy engines, small 2 hp outboards can be found all over the Mediterranean, on charter and owner yachts. The size is completely sufficient to take a fully loaded dinghy from the anchorage to the nearby harbour promenade in calm weather. And the drive is so light that it can easily be lifted on board over the railing with one hand.
However, whenever there is a little wind or the distance to be travelled is a little longer, it helps if the dinghy motor has a few power reserves. The same applies for use as a pusher motor on a small cruiser: in calm weather, 2 hp would be enough to manoeuvre the boat out of the box and through the harbour. However, it is often a good idea to have a safety reserve so that it can return safely to the harbour when the wind picks up.
The right size for dinghies and small cruisers
Outboards with an output of 5 hp are the ideal size for all weather conditions and requirements - both as a small cruiser propulsion system and as a dinghy engine - because their weight (25 to 29 kilograms) means that they can be hoisted on board from the dinghy without the need for a motor crane or major effort and, as a lull pusher, do not make the ship too stern-heavy.
From the next size upwards of 6 or even 8 hp (depending on the manufacturer), the engines are often designed as twin cylinders, which adds weight and makes the drives increasingly unattractive for use on sailing boats. At least if the dinghy is not driven on davits, but has to be constantly freed from the engine and lifted on deck for each leg.
We tested these motors in the 5 hp outboard class
For this reason, we took a close look at four of the most common outboards and tested them uniformly on an average dinghy (Talamex Comfortline TLA 250), measuring fuel consumption and range on one tank of fuel. The engines all have an internal tank with a capacity of between 1.2 and 1.5 litres, which often makes carrying the bulky but optional additional tank unnecessary. The internal tank of all the test candidates is large enough to run at full throttle for up to three quarters of an hour.
The only difference between the Tohatsu and Mercury engines is the second handle at the rear end of the powerhead, which makes it much easier to carry and attach the drive. The cover has a slightly different shape: Tohatsu has a slightly more pointed and narrower aft end, while Mercury's is somewhat rounder. The Yamaha and Honda models are larger and heavier.
All of the engines are very well made and of high quality, although the Honda gives the impression in many details that they have gone the extra mile in production. Both in the finish and in detailed solutions, such as the small hose that can be attached to the carburettor if required to drain the fuel from the float chamber so that it does not spill.
Important labelling missing on the Tohatsu MFS5DD
While when using an external tank, the fuel is sucked into the line via a pump ball and pumped into the carburettor, when using the internal tank, it is usually necessary to make a few attempts to start the pull starter after the tank has run completely empty until the carburettor is completely full. Yamaha therefore has a small pump ball under the cap to pre-pump the fuel from the internal tank. However, the fuel tap itself is not located on the side of the powerhead, but underneath the front, so you have to search a little for the first time. Good: A sticker indicates the correct switch position so that it is clear that it must at least be nearby.
Only the Mercury and the Honda have labelling for correct storage, for example when transporting in the boot. Such labelling is very important because the engine oil can leak or enter the combustion chamber if stored incorrectly. With Tohatsu, you have to leaf through the manual to find out that the engine can be stored on the right, left or front side. Despite being identical to the Mercury, it may only be placed on the left-hand side. Yamaha does not require such a sticker because, according to the manufacturer, it does not matter how it is stored - as long as it is not upside down.
Outboard motor test: good performance for all models
Both the Tohatsu and the almost identical Mercury have the gearstick located at the front. This makes it easier to reach at the stern of a sailing boat without having to lean far over the railing.
When testing the motors, we made do with the original propellers supplied, which are optimally designed for testing on inflatable boats. For use as an auxiliary drive on a sailing boat, many manufacturers offer alternative thrust propellers that have a larger blade surface and flatter pitch in order to improve the properties when accelerating and stopping. However, thrusters are only compromises in this engine class because the small single-cylinder engines with their 5 hp are only suitable for this to a limited extent. Tohatsu, for example, supplies a 7.8 x 8 propeller with the tested engine, with the first number indicating the diameter in inches and the second the pitch. This propeller is ideal for a rowing boat or dinghy, but for a sailing boat Tohatsu recommends a 7.9 x 6 type, which has a slightly larger diameter and less pitch.
Bollard pull measurement shows the true strength of the motors
Only models from 6 hp (Yamaha) or 8 hp are really powerful enough with their two cylinders to be able to use effective thrust propellers with corresponding blade surfaces. What is an advantage with engines can also be a disadvantage when sailing if the outboard cannot be folded out of the water. The large blade surfaces then generate considerable resistance. In practice, many sailors do not realise the differences and therefore use a standard propeller.
In the bollard pull measurement, in which the engines have to pull at full power on an electronic scale, the Tohatsu proved to be the strongest candidate with a pull of 0.61 kilonewtons (kN). At 0.58 kN, the Yamaha generated only slightly less force, closely followed by the almost identical Tohatsu Mercury with 0.57 kN and the Honda with 0.55 kN.
In order to determine realistic fuel consumption during the test drive, we decided on three speeds: a slow drive of five kilometres per hour, a fast displacement drive of nine kilometres per hour, in which the inflatable boat remains just below the planing speed, and a drive at full power.
Speeds, ranges and fuel consumption of the test candidates
As we carried out the test with a dinghy that starts to planing at ten kilometres per hour, the outboard engine consumes less fuel per kilometre at full load because the boat is planing and has overcome the resistance of its own wave. At full load on a displacing sailing boat, however, consumption will be exponentially higher. All drives are very favourable in terms of fuel consumption. In terms of the range of an engine, we differentiate between the range with one litre of petrol (to enable a direct comparison) and the practical range with the different sized tanks.
In purely mathematical terms, the Yamaha is the most economical drive. With a consumption of just 0.14 litres per kilometre in fast displacement mode, it can cover 7.0 kilometres on one litre of Super, making it the furthest. However, it is closely followed by the Mercury and Tohatsu, which have a fuel consumption of 0.15 litres per kilometre and a range of around 6.5 kilometres (on one litre of fuel). The Honda is a little thirstier than its colleagues and requires 0.18 litres with a range of only 5.5 kilometres. At full throttle and when gliding, the Tohatsu comes out on top, which is the fastest at 27 kilometres per hour and therefore has a range of 16.6 kilometres with a full throttle consumption of 0.06 litres per kilometre at higher speeds. In practice, with its built-in 1.2-litre tank, it could even travel up to 20 kilometres. The Yamaha, on the other hand, only reaches a top speed of 24.5 kilometres per hour with a fuel consumption of 0.07 litres, giving it a range of 13.7 kilometres. In practice, it would manage 15.1 kilometres with its small 1.1-litre tank. Although the Honda requires a little more fuel, it also has the largest tank at 1.5 litres, which gives it a range of 15.3 kilometres.
This means that almost all engines achieve a practical range at full throttle of 15 kilometres or a travel time of between 36 (Yamaha) and 44 minutes (Tohatsu), which should be sufficient for most purposes.
