Greener outboards

Post by: TheYachtMarket News
03 July 2009

More fuel efficient and environmentally friendly outboards are coming on to the market all the time.

Honda has taken a very successful engine, the BF50, and put it through an environmental make-over. They wanted a lighter unit, better mid-range efficiency and a throttle second to none when opened at the top end.

BLAST

Honda’s research and development experts took the proven 3-cylinder 808cc (49.3cu in) block, and tweaked it with a combination of lighter components and sophisticated software. The Boosted Low Speed Torque (BLAST) software programmed is designed to eke out the fuel without compromising performance. It uses an oxygen sensor to enrich the fuel mixture to get the boat on the plane, and then makes it leaner again when you’re settled at cruising speed – which is where these types of engines spend most of their time. Combining with BLAST is EcoMo, an engine management system using complex electronics with which Honda hopes to save 22% of fuel compared to the earlier BF50 model.

Streamlining

The lower gear assembly is much thinner so as to minimise drag, although the gear ratios and the prop size remain unchanged. There is a modified anti-cavitation plate, designed to ease the flow of water past the leg, and lightweight plastic manifolds have been used to help make the BF50 the lightest in its class. It ranges from 205lb through to 215lb depending on the configuration.

Sitting on top of the machine is a beast of an alternator, mainly as a response to American demands. Fishfinders and beer chillers are very popular with American fishermen, and with 44 million boat-anglers in the United States manufacturers want to supply enough electrical power to keep them happy. Using a bi-polar system has a larger-coil, the alternator pumps out 17A, getting on for twice as many and its predecessor.

On the water

The BF50, and its detuned sister the BF40 (same engine, lower spec for European tax reasons) can be supplied either tiller-or wheel steered. On the tiller version the handles are centred, and have been made longer, with all the control falling easily to the fingers. Friction locks prevent throttle slippage, and there are two shaft lengths available on the BF50 of 20 or 25 inches.

Weight savings

The engine is slightly noisier than other similar 4-strokes when opened up. This may be as a result of making weight savings in some components. Density does dampen noise, but it’s a small price to pay for a potential saving of a fifth of your fuel bill every season. The offset crankshaft leading to compact size allows the engine to suit most powerboats in the 14 to 20 foot size range, and is especially suited to open dories and small RIBs. Being a 4-stroke, it can happily idle away all day, so would also be well suited to larger rivercraft.

The future of outboards

Honda seem to be keen to address environmental issues, with an engine that easily meets the California Air Resources Board 2008 emissions regulations (the world’s strictest). And should you wish to dispose of your BF50, it’s 93.6% recyclable.