Talking Torque: Less Stress

Lower revs mean a longer lifespan

Most three-cylinder diesels in the 30hp range develop maximum power at 3600rpm — fine for racing yachts, not cruising yachts. Being able to run an engine at around 2000rpm is way more comfortable than at 2500rpm, let alone 3600rpm.

Westerbeke's three-cylinder 35E is one such engine. The Mitsubishi-based engine has been marinised to develop maximum power at 3000rpm, giving it a longer lifespan than its higher-revving competition.

Modified and marinised from a 1.6L Ford Cortina car engine, the Watermota Sea Panther developed 27 brake horse power at 2500rpm (fairly high revving for its time), but was cantankerous and didn't suit conversion to a diesel particularly well — odd considering Watermota has been well known for its marinisation of car engines for decades in the UK. As parts became harder to find owners would re-power with engines like the 954 cc Yanmar 3GM 30 but developing 27bhp at 3600rpm this was insufficient power for the 32. This is where the 28bhp 35E scores. It develops 28bhp at only 3000rpm with way more torque and at lower revs.

THE NITTY GRITTY

As with the Mitsubishi-based Westerbeke 12D and 44C, both of which develop maximum power at 3000rpm, the three-cylinder 35E is an overhead valve design with camshaft-driven push rods operating the rockers. Even though the base engine was designed for tractor and industrial usage, Westerbeke has modified it with a deep sump that allows for 30 degrees of heeling for up to 30 minutes, very handy for motor sailing as deep keel yachts like the 32 tend to sail best when well heeled. The maximum static installation angle is 14 degrees and in normal straight gearbox output installations the angle is likely to be around eight degrees, so there's provision for fore and aft hull pitching when under way.

Like its counterparts there's no provision for hand starting, which would need a raised crank handle with freewheeling release (to prevent wrist breakage should the engine kick back) and decompression levers. Of course with a 22:1 compression, even if decompression levers were fitted the cranker would have to be pretty strong to keep the engine spinning when compression came on!

Heat exchanger cooling is standard, to maintain reasonably constant engine temperatures of 80 to 90 degrees and reduce condensation in the lubricating oil sump from the temperature difference between the combustion chambers and the cooling system that often happens in raw (sea) water cooled engines. The combustion chamber condensation passes the piston rings and ends up in the sump where, over time, it dilutes the oil and reduces its lubricating effectiveness. The cooling system has a 4.7 litre capacity, more than adequate for tropical conditions.

A camshaft-driven rubber impeller supplies the raw water to the heat exchanger while a centrifugal pump circulates coolant and is driven by a V-belt that also drives the 50A voltage regulated alternator. As with its counterparts, there's no cover over the belt as Westerbeke obviously thinks no one would be stupid enough to poke their fingers around a rapidly moving belt.

The starter motor is mounted well above the engine mounting feet and the 35E needs a battery of at least 237 cold cranking amps (CCA) capacity so a standard 40Ah starter battery would do the job. I've always used batteries that exceed an engine's minimum CCA requirements to allow for battery output losses as it ages. A 40Ah battery can supply around 350–370 CCA, giving a margin of starting safety, especially as the 35E has glow plugs for cold starting that consume a fair amount of power.

At 3.7 litres, the oil sump capacity is comparable to some 1.8 litre automotive engines and can handle some oil dilution from running the engine under light loads. Westerbeke doesn't mention the recommended oil viscosity but I suggest using a diesel-specific SAE 15W40 oil for temperate climates and a SAE 10W30 oil for cold climates, such as when cruising the Southern Ocean. I also suggest changing the engine and horizontally mounted oil filter every 100 running hours or annually. If you're a yachtie who sails up to a mooring or into marinas and rarely uses the engine, I suggest changing engine oil and filter every 50 running hours or six months. Fresh oil is the key to engine longevity, but frankly if I'd gone to the expense and effort of re-powering a yacht the engine would get a lot of use, including when approaching moorings!

The standard mechanical gearbox has a 2:1 reduction ratio and complete with this, the 35E is 777mm long, 542mm wide and 574mm high, so it's not a bulky engine for its output. 

However, the 35E doesn't come with a tachometer as standard and to me that's essential for matching prop dimensions with the engine revs. I believe all inboard engines should be equipped with a tacho and Westerbeke offers two instrument panels. The lesser ‘Captain’ unit has an analogue tachometer with digital hour meter and warning lights and alarms for low oil pressure, engine over heat and alternator charging failure; the upmarket ‘Admiral’ panel has gauges instead — way better for monitoring engine health.

THE WRAP

Of course the 35E would suit other cruising yachts too, such as the 5.8 tonne Arends 33, but unfortunately these are holding their value way better than the Nicholson 32 and can fetch upwards of $60K, a lot of outlay for a 30-year-old yacht of this size.

The 35E retails for an affordable $11,000 and combined with around $25K for an older 32, even with new stern gear the total outlay should be around $40K. In my opinion that's good value for a yacht capable of ocean crossings. From my experience of testing small three-cylinder diesels the 35E should be unobtrusive when running yet have the torque to enter ports that have strong tidal flows, and while the 35E doesn't have the torque of its slightly heavier four-cylinder 44C counterpart it actually has more usable torque relative to output.

For more on the 35E call Marine Energy Systems on (07) 5502 7771 or contact sales@marineenergy.com.au 

QUICK SPECS

Westerbeke 35E

Engine type Three-cylinder indirect injection diesel

Rated BHP/MHP 28/28.4 at 3000rpm

Maximum torque 69NM at 2000rpm

Piston displacement 1318cc

Bore x stroke 78 x 92mm

Dry weight w/box  175kg