Issue: September 2005
Like anything that is totally new and definitely outside the square of thinking, it takes a little time for an industry to accept it. Such is the case with Volvo Penta’s revolutionary Inboard Performance System (IPS) drive units.
Many of the major European manufacturers have readily installed the new system in their models with huge success and now Mustang Cruisers, the second largest boat builder in the country, has been quick to realise the potential of the new system. The Gold Coastbased company is the first boat builder in Australia to install the revolutionary system and has done so in a Mustang 46.
Volvo Penta’s IPS is a complete package that includes everything from the steering wheel, controls and instrumentation, to the engine propulsion unit and propellers.
Forward Facing Props
The engines are coupled to steerable propulsion units that are mounted on the underside of the boat’s hull, forward of the transom, in specially designed cutouts that are integrated in the hull structure.
The propellers face forward and pull instead of push. This sends the propeller backwash parallel to the underside of the hull, so that all the power drives forward, while the twin-prop concept with counterrotating propellers cancels out rotation losses. It is the same principle used on propeller-driven aircraft , which normally have propellers facing forward in the direction of the aircraft ‘s travel.
The steerable propulsion units provide an entirely different steering control to a conventional twin shaft -drive with rudders. When the units are turned the entire propeller backwash and all the thrust is directed straight back behind the boat. As a result the boat turns rapidly, even at low speeds, and is as easy as a motorcar to manoeuvre.
Dick Johnson At The Helm
V8 Supercar legend and now team boss, Dick Johnson, bought the first Mustang 46 fitted with the system, replacing a conventional shaft drive Mustang 46 he previously owned.
Dick won’t take delivery of the boat for about four weeks and so far he hasn’t driven it. But when he does he will certainly notice a difference in the performance between the two boats. Late last year I drove a European boat of similar size with the system fitted and came away impressed by the performance. Recently, I got to drive the Mustang 46 and if ever a propulsion system was suited to a boat, it’s this one.
The 46 jumps onto the plane in just eight seconds, which is quick for a boat of this size and weight, and it stays there happily at 13 knots. At this speed the engine management system shows each engine using only 32lt per hour.
Push the electronic controls all the way forward and the speed jumps to 31.5 knots at 3500rpm, with the readout showing a fuel burn of 75lt a side per hour.
This is about 20 to 30lt less than a shaft drive 46. The old 46 was driven by 480hp diesels, while the new system allows the smaller Volvo Penta 370hp D6s to be fitted and this gives better fuel economy and a far better performance.
During the time we were onboard, the 46 was still in test mode. The cabin furnishings still needed to be finished off and there was no sound insulation in the engine bay whatsoever.
Despite this the D6s were super quiet. At 3000rpm the sound-level meter recorded 82dB in the cockpit and just 78dB in the cabin, which is lower than normal sound level standards.
Performance & Handling
The power comes on smoothly with not a hint of vibration and the ride has also improved dramatically. Instead of falling off the back of a wave in a seaway, the 46 now rises over the swell.
The IPS has also made a big difference to the handling of the boat. The original 46 needed a degree of expertise to handle, especially in a crosswind when coming into a berth. With the IPS the boat can now be parked in a marina berth as simply as backing a car into a supermarket parking space (and that’s without a bow thruster). You can have one if you want, but you won’t use it very oft en, although admittedly, it could come in handy on a very windy day. The system will make a driver with limited experience look like he has been doing it for years.
Those brave enough to throw the boat into a tight turn at speed will see that not much happens. It just sits in nicely without a hint of cavitation or tail slippage. The more the fly-by-wire steering is wound on the more the boat turns.
Sure it will wash off a few knots as the turn tightens, but straighten up and it just accelerates away.
Even hard-bitten skippers like Charles Koole, who does much of Mustang’s test driving, is impressed. According to Mustang’s Garry Garoni, once people drive a boat with the Volvo Penta IPS they won’t want a shaft drive ever again. ‘We are now considering fitting the system to our 38 and 42 models,’ he said.
Perhaps Dick Johnson best sums up the whole thing when he says that the simple things are always the best.
Mustang Cruisers was established in 1974. Now, with 28 years of boat building excellence and a stable of quality sportcruisers under its belt, it has earned an enviable worldwide reputation.
According to the Mustang team, from initial design concepts to pre-delivery detailing, and all manufacturing processes in between, the Mustang Cruisers team takes great pride in delivering vessels worthy of wearing the Silver Stallion. It has developed rapidly in recent years to become Australia’s second largest boat builder and can boast North America, Japan, Singapore, China, Denmark, France and The Bahamas among its current export markets.
At present the Mustang production facility employs more than 200 people, as well as the many local businesses that work for under contract.
The first Mustang 46 was driven by 480hp diesels, while the new system allows the smaller Volvo Penta 370hp D6s to be fi tted, which gives better fuel economy and a far better performance.
This new Mustang 46 fitted with the new Volvo Penta IPS and powered by a D6 370hp diesel hit 31.5 knots at 3500rpm with the readout showing a fuel burn of 75lt a side per hour. This is about 20 to 30lt less than the shaftdrive 46.
LOA: 48′ 5′
BEAM: 14′ 2′
DEADRISE: 18 degrees
ENGINES: Twin Volvo, Penta D6 370hp diesel
DRIVE UNITS: Volvo Penta IPS
SLEEPS: Four adults
+ Superb maneouvrability
More speed from less power
– Nothing to report
Words by Kevan Wolfe