Talking Torque: Houseboat Power

Andrew Norton — 11 June 2020
The Westerbeke 8.0 SBEG, with its quiet, low vibration output and good price, is a convincing petrol alternative for a houseboat.

For larger houseboats powered by four-stroke outboards, this petrol genset makes good sense. Why have the weight and expense of a diesel genset and different fuel aboard when there's a petrol alternative? Or have to deal with mechanical engine control when you can have plug-in diagnostics just like an EFI outboard?

With its under-stressed engine spinning at a lazy 1500rpm, the 8.0 is quiet enough not to need a bulky soundproof enclosure, but will still power the onboard electric galley, air conditioner and a hot water system. Yet the dry weight is 210kg, only four per cent heavier than Westerbeke's 5.0kW diesel genset.


Power comes from a 1.5 litre four cylinder OHC engine with an iron cylinder block, aluminium head and five main bearings. Combined with an electronic engine governor, the multipoint EFI reduces bog down when compressor-based loads such as fridges and air conditioner units are switched on, while the EFI with its electronic control unit has a full diagnostic facility for quick analysis of any operating faults. The engine also has provision for full-torque power take-off and for running equipment such as mechanical winches.

The engine has heat exchanger cooling with expansion tank and raw water cooled exhaust. The cooling system capacity of 5.7 litres is large for a 1.5 litre engine and should handle hot climates, such as on the Murray River, with ease. The fresh water circulating pump has its own dedicated belt drive with idler pulley tensioner. 

The 3.3 litre oil sump is also large for the engine displacement. Sensibly the canister oil filter is angled downwards so that when it's replaced oil won't run all over the cylinder block. Westerbeke doesn't recommend a suitable oil viscosity, but for temperate climates I suggest an FCW SAE 10W30 oil, the same as many four-stroke outboards use, eliminating the need to keep separate oils on board. Once started the engine revs immediately to 1500, about the same as an EFI petrol car engine when cold, and the 10-weight base oil will ensure the bearings are fully lubricated before load is applied. I also suggest changing the oil and filter every 200 running hours or annually.

The air-cooled brushless 34A alternator has excellent voltage regulation of +/- 2 per cent and +/- 1 per cent frequency regulation, enabling frequency-sensitive appliances, such as laptops and TVs, to be charged and operated without fear of damage. Unusually, it can be switched from 50 to 60 Hz for a higher output, but only for non-frequency-sensitive appliances such as halogen lights. Back in the days of incandescent lights many portable gensets had this feature but this is not so useful now that most lights are LED, which require specific frequencies. 

A separate alternator with its own dedicated drive belt provides up to 50A for charging the starter battery. A minimum 150CCA (Cold Cranking Amps) battery is needed for starting the engine, although a 40Ah car battery with 330CCA would be more than adequate. A shroud encases both the alternator and freshwater circulating belts.

The 8.0 SBEG measures 859mm long by 554mm wide by 638mm high and would need to be fitted in a compartment with adequate venting for the hot alternator air. A cooling water intake seacock with strainer would also be needed with a topsides exhaust outlet to direct gases away from living areas, but obviously, being petrol, exhaust fumes would be way less than a diesel genset. And, of course, you’d need a RACOR water separating fuel filter if feeding from a separate dedicated fuel tank. Fortunately, as the EFI is non-returning like EFI outboards, complex return lines to the tank are eliminated.

The 8.0 SBEG meets all current CARB (California Air Resources Board) and US EPA requirements for petrol genset exhaust emissions and complies with US Coast Guard 33 CFR — 183 specifications for onboard petrol gensets.

The unit has engine warning alarms and automatic shutdown for engine over-speed, high exhaust temperature and low oil pressure. 

The factory warranty is five years for recreational usage.


It's a sad fact of life that it's easier for petrol gensets to achieve strict exhaust emissions compliance than diesels. I think there's a real future for petrol gensets especially when powered by LPG and, with the trend for high-power petrol outboards to replace diesel stern drives, having one fuel aboard is just common sense. Modern four-stroke outboards are relatively frugal when not run at or near Wide Open Throttle, even under high load applications such as pushing large houseboats at displacement speeds, and are quiet too. So why ruin a quiet riverside anchorage with the noise of a diesel genset?

As of March 2020 the 8.0 SBEG retailed for $18,700 including GST.

For more on the 8.0 SBEG visit Marine Energy Systems at or call +61 (07) 5502 7771. 


Genset Westerbeke 8.0 SBEG

Engine Four cylinder OHC EFI petrol

Max output 19.0 brake horsepower at 1500rpm

Displacement 1466 cc

Bore x stroke 75.4 x 82.0 mm

Alternator Brushless

Voltage 230 +/- 2%

Frequency 50 Hz +/- 1%

Engine and alternator dry weight 210kg

*Brake horsepower/metric horsepower or PS


Talking Torque Westerbeke 8.0 SBEG Low vibration Houseboat alternative