More than torque

As mentioned in the review of MAN's V12 1500, competition in the 1500hp market is currently very stiff. In Australia the hull everyone's chasing is the Riviera 58, which performs best with twin installations in the 1400-1600hp range.

There's no doubt that at two tonnes bobtail weight (minus gearbox) the MAN V12 is the lightest diesel in its horsepower class, even lighter than MTU's Series 2000 V12. But as I've stated in the past, the more important factor to consider is not the power-to-weight ratio but the torque-to-weight ratio. And this is where the electronically managed 30lt V12 Cat C30 really scores.

The motor complies with IMO requirements for exhaust emission control.

INCREDIBLE TORQUE OUTPUT
Displacing 30lt with a bore of 145mm and stroke of 152.4mm, the C30 is a fairly imposing engine for its output. But although at 2547kg bobtail it's 29% heavier than the 21.9lt MAN V12, it produces 32% more torque, or an incredible 6203 Newton metres at 1500-1800rpm without requiring four turbos to do so.

However, the torque rise is not as rapid as the MAN V12. At 600rpm the C30 produces 2700Nm, at 800rpm 3000Nm and at 1000rpm 3500Nm. From there the torque rise is steeper, 4500Nm at 1200rpm and 5500Nm at 1400rpm, while on the upper side of the torque "plateau" at 2000rpm the figure is 5700Nm, at 2200rpm 5000Nm and at 2300rpm 4700Nm.

These revs are also the maximum, where the C30 develops 1156kW or 1550hp according to 1.0hp = 746W, the measurement used by Cat Marine in accordance with the US National Marine Manufacturers Association and ISO8665 requirements.

Caterpillar says it maintains ISO9000-approved engine test facilities to assure accurate calibration of test equipment. The C30, for example, is rated at 52° of ambient air temperature and the same fuel temperature, whereas some diesel manufacturers rate their engines at cooler temperatures where the air is denser. Propshaft horsepower is only 3% less than the crankshaft figure quoted.

European and Japanese diesel manufacturers use the PS measurement where 1.0hp = 735.5W, leading consumers to believe they are getting more power for their money when the converse is true!

As with all electronically managed diesels, the fuel usage rate is very reasonable for output. Based on a standard propeller power curve, at 600rpm the consumption is 7.6lt/h, at 1000rpm 26.9lt/h, at 1200rpm 43.4lt/h, at 1400rpm 67.2 lt/h and at 1500-1800rpm 82.1-138.7lt/h. At the maximum continuous cruising revs of 1900rpm the usage is 161.9lt/h, at the maximum cruise of 2100rpm 220.5lt/h and at Wide Open Throttle 317.3lt/h.

Cat Marine supplies the C30 with an "E" rating suitable for planing hull vessels such as pleasure craft and some fishing and pilot boats. The annual duty cycle rating is up to 1000 hours with one hour of WOT operation in every 12.

For its massive displacement, the C30 is not a bulky engine. It is 1997mm long, 1413mm wide and 1378mm high, more than 100mm lower than the MAN V12 while just over 50mm wider. And surprisingly the C30 is more than 20mm shorter!

As with all Cat Marine engines, the C30 has an impressive list of standard features including an aircleaner with positive crankcase ventilation, gear-driven salt and freshwater cooling pumps, an engine-block heater on each bank of cylinders and a titanium plate heat exchanger.

The hydraulically actuated electronically controlled unit fuel injectors automatically alter the fuel spray timing not only according to revs but also engine load, ambient temperature and barometric pressure, allowing the timing to retard under heavy loads and advance once the load has dropped. This prevents engine overloading in heavy weather, while allowing the engine to take full advantage of relatively light load conditions such as when the hull is fully planing.

The instrument panel has a start/stop switch, emergency button, maintenance-due lamp, diagnostic lamp, electronic service meter, warning lamp and 15amp breakers. A digital tachometer, oil and fuel pressure gauges, and water and oil temperature gauges are provided. Accessories include a transmission oil pressure and temperature alarm system, 24V 60amp alternator (the standard electrical system is 24V), heat exchanger fuel cooler for tropical climates, a GPS interface module, hydraulic pump drives, fuel and water separators and a full spare parts kit.

Cat Marine recommends changing the oil and filters at 200 operating hours and using Caterpillar DEO SAE10W30 or 15W40 oil in the 85lt sump. Twin engine installations have handed engine service access points where the port engine is serviced from its starboard side and the starboard engine from its port side, simplifying C30 maintenance.

COMPLETE CAT SERVICE
Garry Dann of Energy Power Systems, the Australian distributor for Cat Marine, told me that the company fully sea-trials every engine before it is delivered to the customer. Testing includes exhaust gas temperature and engine loading analysis across the entire rev range to ensure the engine is propped correctly for the hull, a problem faced by most engine distributors in this country through the ignorance of some boatbuilders.

But Garry stressed that the engines are trialled under light load conditions, which don't include a full fuel load, an over-abundance of passengers and owners' personal effects, and which, combined, can significantly blow out the laden displacement. The boatbuilders should take these additional weights into account when choosing props, as it is always better to slightly underprop an engine than overprop it.

Caterpillar has been long regarded as having one of best logistics networks in the world, allowing it to rapidly supply service or spares to most regions.

For more information on the C30, contact Garry Dann at Energy Power Systems, tel (07) 3272 1677 or email at garry.dann@energypower.com.au.