Vessel: Thomascraft 4300
Vessel Weight: 17 Tonnes (approx.)
Old Engines: Caterpillar 3208 - 375Hp @ 2800rpm
New Engines: FPT NEF 450s - 450Hp @ 3000rpm
Gearboxes: Twin Disc MG507 - 2.0:1 Ratio
Vessel Cruise Speed: 20 knots @ 2400rpm
Vessel Top Speed: 27 knots @ 3000rpm

The Thomascraft 4300 is an extremely well renowned hull in Western Australia. They have an excellent internal layout and are known for their excellent sea keeping abilities. This 4300 was powered by Caterpillar 3208 Marine Engines, however the increasing unreliability of these old Cats, and the cost of repairing them made re-powering a very attractive option.

With the involvement of THT, we were able to offer a very cost effective re-power because we are flexible and will try to reuse as many components within the engine room as possible to keep the overall re-power costs down.

In this instance, the Cat 3208 engines has Twin Disc MG507 gearboxes in a 2:1 ratio behind them. Both the Cat 3208 and the NEF 450 share the same SAE 3 bellhousing. The only difference is that there is an “ear” on the SAE 3 Cat housing, where the starter motor bolts to. THT are able to cut off that additional “ear” and when it is removed, the Twin Disc gearboxes will bolt straight onto the FPT NEF 450 Marine Engines. Before we bolted them on however, they were sent to Twin Disc for repair and testing, to make sure they were in excellent operating condition.

The exact Cat 3208 marine engines in this Thomas craft 4300 are 375Hp @ 2800rpm each. The client opted for the new FPT NEF 450 Marine Engine, which is an inline 6 cylinder, 6.7 litre common rail fuel injected engine set at 450Hp @ 3000rpm.

Having reused the gearboxes, the rear mounts are connected to the gearbox so therefore they fitted straight back onto the existing mounts. Only the front mounts required modification, and even then the difference was only 20mm forward, and 60mm upward, meaning that no modifications to the engine beds were required in this re-power whatsoever. A great cost saving to the client. We were also able to reuse his exhaust system, fuel lines, sea water intake system, morse cable throttle system and 24V battery cables too.

The new NEF 450s performed exceptionally well at sea trial, achieving 20 knots @ 2400rpm cruise speed, burning 35 litres per hour per engine (approx.) and a top speed of 27 knots @ 3000rpm.

The client is extremely impressed with how quiet the new NEF engines are, as well as their low fuel consumption and excellent performance, the vessel has never performed so well.

A new generator was also supplied at the time of re-power, a Coelmo DML740, producing 7.4kVA @ 1500rpm and powered by a Kubota 3 cylinder diesel engine. This is contained in a soundproof cabinet, and fits very neatly toward the rear of the vessel.

For more information on this re-power, please contact us!