Choosing an Outboard Motor For Your Dinghy
30 years ago American manufacturers dominated the outboard motor market.Names such as Mercury, Johnson, Evinrude and Chrysler, led the field competing with each other to produce bigger and better outboard engines. However, while this was going on they Suzuki outboard motors were neglecting the smallest of the outboards. These are the outboard motors that sell in the greatest of numbers and are often the first outboard many of us, buy. This being the case many of us stick to the same brand (brand loyalty) as we buy other bigger outboards over the years. The Japanese seized on this fact and gradually Honda, Yamaha, Suzuki and Tohatsu concentrating on small outboards began to take over as market leaders. They achieved this domination by improving efficiency and reliability. As well as adding features to these small outboards previously only found on larger engines.
Having achieved success in the small outboard market, these Japanese manufacturers expanded up the power range. They again came to dominate the outboard engine market up to at least 20 hp. The American manufacturers instead of competing with the Japanese, gave up and decided to buy these engines from the Japanese and badge them as their own. Now the Chinese have entered the market. Basically doing what the Japanese did previously, copying the best features of the present engines and at the same time keeping costs down.
So let us compare the outboards that are on offer for those looking for an outboard motor for their dinghy. If we take a fairly larger dinghy say, a Pioner 12, so that each outboard has to push a reasonably heavy weight through the water. If we then take the following outboard motors :
Mercury 2.5hp; Mercury 3.5hp; Mariner 2.5hp; Tohatsu 3.5hp; Yamaha 2.5hp; Suzuki 2.5hp; Honda 2.3hp; and a Parsun 2.6hp. All these outboards are 4 stroke engines. This is due to an E.U. Directive that prevents 2 strokes from being sold in the E.U. These outboards will provide a fairly wide range of engines available on the market, for powering dinghies.
To judge one engine against the another several tests were completed. A Bollard pull test showed that the Mercury 3.5hp and Tohatsu 3.5hp were the most powerful at 90lbs of thrust (These two engines along with the Mariner are virtually identical). The least effective was the Honda 2.3hp at 66lbs of thrust. In between were the Suzuki 2.5hp at 83lbs of thrust, the Yamaha 2.5hp at 78lbs of thrust and the Parsun 2.6hp at 70 lbs of thrust.
Next test was Fuel Consumption. At full speed – 5.75 knots, the best outboards were the Yamaha 2.5hp and the Suzuki 2.5hp by at least 20%. The worst was the Parsun 2.6hp. When the throttles were eased and the dinghy was cruising the Fuel Consumption comparison was less evident, only about 10% difference. All these figures are for 4 stroke engines. However, based on figures previously recorded for 2 strokes under similar circumstances, the older engines were up to 50% less fuel efficient at full speed. Very thirsty! Remember 2 stroke outboards are still available second hand.
Then the weight of each outboard motor was compared. Four stroke engines are heavier than older 2 strokes because of the powerhead etc. The Mercury, Mariner, Tohatsu, Yamaha and Parsun all weighed approx. 38 – 41 lbs (18 kg.). However, the Honda 2.3hp and Suzuki 2.5hp weighed a lot less at 28 lbs (12.5 kg.).