Reinventing the wheel

The scale of the event was the first clue. Almost 70 marine journalists and editors from publications across the globe and their distributor hosts, Volvo Penta's heaviest of corporate heavyweights, a test fleet of boats complete with requisite manufacturers' representatives... even a television crew.

And all flown or shipped at great expense to a five-star (and then some) resort on the Spanish island resort of Mallorca. Hell, Volvo Penta even had the corporate jet on hand.

Though nothing had been officially stated or even unofficially leaked, Trade-A-Boat was on the ball and knew a little of what to expect. In fact, we'd first heard of the marine pioneer's 'next big thing' as far back as mid 1998. That said, more than three quarters of the writers on hand were in the dark... totally!

What was unveiled after thousands of hours and kilometres of testing in the not-so-sleepy Balerican seaside village of Palmanova rocked their world - a totally new, deeply innovative and literally mould-breaking big-boat drive system that looked more like it had escaped from the set of Thunderbirds than Volvo's R&D headquarters in Gothenberg, Germany.

WHAT VIPS?
Put in simplest terms, Volvo Penta's Inboard Performance System (IPS) is a close-coupled integrated propulsion system.

Providing more than just a drive, IPS incorporates everything from wheel, gear and throttle controls and instruments through to the engine, cooling system including intakes, exhaust, drive and steering gear in one integrated unit. Plug in and play on a grand scale!

Designed to be used in twin installations only (at least initially), IPS features the latest-generation turbo and supercharged electronically controlled diesel engines directly mated to steerable through-hull drives that feature forward-facing duoprop propellers. Yep, that's right: forward facing.

At launch, two models will be offered: IPS 400 and IPS500, which Volvo Penta says will cater to planing craft ranging from 37–50ft and upward.

The nomenclature gives a clue to the step forward in efficiency Volvo Penta is claiming for IPS. The models are named according to the relative on-water performance they generate, says the company.

Featuring Volvo Penta's latest D6 310hp powerplant, IPS 400 delivers performance comparable to conventional twin 400hp shaftdrive installations. With twin D6-370s, IPS 500 yields - you guessed it - the sort of oomph the boating world has come to expect from twin 500s. 

PERFORMANCE GAINS
Indeed, Volvo's not shy in making claims for IPS. According to Lars Ljungqvist, Volvo Penta's Senior VP Product Development, the drives deliver improved efficiency of around 35 per cent compared to conventional shaft installations, 20 per cent higher top speed, 15 per cent better acceleration, 30 per cent more cruising range and 50 per cent improvement in NVH (noise vibration and harshness).

Such performance gain is a hefty claim; however, Volvo Penta says it can back it up thanks to the IPS's blend of drive, drag and mechanical efficiencies.

The key to the units' drive efficiency is multifaceted. A look at the diagrams and photos hereabouts should give you a clue as to the factor that generates the lion's share - efficient horizontal thrust.

As any boat designer worth his or her salt will attest, the bugbear of inboard boat designers is shaft angle. The very fact that propellers drive at an angle means that losses are generated. Though acceptable in some applications, as speed becomes more important to boat buyers, flatter shaft angles are sought to maximise the efficiency of bigger and bigger engines.

The very nature of conventional shaftdrive installations limits the ability of designers to accommodate the changes required. Though prop tunnels can be used successfully to reduce shaft angles, such measures don't address the relative inefficiencies of dragging increasingly larger shafts and attendant hardware through the water. Volvo contends that the real solution was a change in thinking.

According to Lennart Arvidsson, technical project leader for the IPS system: "Conventional inboard installations were beginning to seem like a dead end - it simply was not possible to squeeze much more out of the technology." Enter IPS.

Arguably the biggest shock in the unveiling of IPS was the forward-facing props. Mounted at the forward end of the propulsion unit, facing in the boat's direction of travel, the contra-rotating duoprops 'pull' (aircraft-like) rather than 'push' as conventional boat propellers do.

"Forward-facing propellers are logical," said Arvidsson. "It's just that no one has taken this approach before in our industry. Because the propellers are mounted at the forward end of the propulsion unit, they work in undisturbed water for maximum efficiency."

Further, because of the configuration of the drive, the special nickel-aluminium-bronze alloy propellers' thrust is parallel with the bottom of the boat, meaning propulsion losses are further minimised.

Drag is significantly reduced due to the design of the IPS underwater gear case. It's further optimised by water pickups, exhaust outlets and so on being designed as part of the IPS module.

FLY-BY-WIRE MANOEUVRABILITY
And it's not just more efficient in a straight line, says the company. Each propulsion unit is steerable (through 26 degrees) meaning the entire propeller thrust is aimed in the desired direction.

This makes IPS-equipped boats more manoeuvrable than those with a conventional installation with a fixed propeller and rudder. More akin to a jet drive, in fact.

Alone with practical demonstrations of standing-start acceleration and top-speed comparisons (see box story p74) Volvo graphically illustrated the extra manoeuvrability of IPS-equipped craft when its Cranchi 41 Mediterranée 'mule' equipped with an IPS 500 equipped literally turned through two complete loops in the time (and half the space) it took its conventional-configured twin to do one top-speed revolution.

After holding on white-knuckled through several Continental colleagues' attempts to turn the Cranchi sportscruiser and Fairline flybridge test craft inside out, I needed no more convincing. In fact, Volvo may be well served to tone down the abilities on production versions.

The entire system - from steering wheel to propulsion units - is electronically controlled and integrated with Volvo Penta's EVC (Electronic Vessel Control) electronic platform. Each propulsion unit is linked to steering gear powered by an electric motor. The system processes the driver's steering-wheel movements and converts them into steering movements of the propulsion units.

The computer-controlled setup takes into account boat speed and is progressive, making it easier to turn the wheel at low speeds. This is similar to the latest multi-ratio automotive power-steering systems from makers such as BMW.

"During development of the steering system, safety was a high priority - the primary consideration being that it should be possible to reach harbour safely under any circumstances," says Arvidsson. "All functions are duplicated, and in the worst case scenario it is possible to turn the propulsion units manually."

On-water testing revealed that the one-engine operation is also extremely efficient, with a significant proportion of manoeuvrability retained.

Aimed at making berthing a boat as easy as parking your car, especially for newcomers to boating, it's my belief that the system will, conversely, require old salts to go through a little 're-tuning' - especially when manoeuvring in close quarters. For example, the IPS boats we tested were reluctant to spin on throttles alone, and berthing was best achieved using a mix of wheel and judicious throttle application.

Different, and a little challenging at first - especially in windy conditions. 

AND IF THE WORST HAPPENS...
As the story goes, there are two types of skippers: those that have, and those that will. Running aground a shaftdrive boat is never pretty. Bricking an IPS-equipped boat won't be either, but Volvo maintains that a key safety feature of the IPS system is that it is designed to reduce the damage caused by running aground.

The company says the propulsion unit is robust and is built to withstand low-speed groundings - at low speeds in marinas or soft grounds such as sand or mud.

Under more severe collisions - if the boat runs aground or strikes an object in the water at planing speed - the propulsion unit is designed to break loose at predetermined break points, thereby protecting the hull from damage and reducing the risk of flooding.

This degree of sacrificial design also simplifies repair work, since the entire propulsion unit can be replaced with a new one. The extent of 'salvageability' of the broken unit will probably be a discussion point as IPS gains market penetration.

One senior Volvo Penta engineer stated that it took repeated attempts to actually 'de-drive' a boat in testing. The graphic footage of the trial the company showed during the launch presentation made every regular boater in attendance wince.

By the way, Volvo states that IPS has excellent corrosion resistance. All components that come into contact with the water are made from either bronze or stainless steel, and the propellers consist of a special nickel-aluminum-bronze alloy.

The propulsion unit itself does not require antifouling. Our only concern was the potential for growth in the cooling-water inlets and on, or adjacent to, the hull/drive join.

BUILDERS' LABOURS
Simplified installation for boatbuilders is touted as one of the key benefits of IPS. The units tap into the trend Volvo Penta kicked off with its EDC range of engines, which arrive complete with controls, instruments and so on.

The IPS systems are close to turnkey with (as stated in the intro) everything a boatbuilder needs to make the boat move, from steering wheel to propeller. Volvo is even developing a bespoke autopilot.

The aperture through which the drive and engine are coupled is moulded into the hull using a blank to Volvo's design. Minimum and maximum distances from the drive to the transom are specified with 500mm deemed ideal.

Volvo says sportscruisers and the like, which would have used stern or V-drive propulsion in the past, can be reconfigured to use a close-coupled IPS system. For conventional flybridge installations that require a low cockpit floor and forward mounting of engines, a 1.7m jackshaft kit will be offered.

Each propulsion unit is placed from beneath the hull using two large O-rings for sealing and vibration damping. A clamping ring completes the installation. No drilling or through-hulls are required.

The clamping system is such that all the propulsion forces are absorbed by the hull and not transferred to the engine beds.

This in turn allows 'softer' engine mounts to be used for even better isolation of engine noise and vibration. No shaft alignment is required.

The propulsion unit also performs exhaust functions. Already 'clean' diesels, the D6's emissions are expelled into wash beneath the boat, reducing the levels of fumes and noise onboard.

As the drive units also effectively control the distance of the propellers from the hull, there's no risk of prop-clearance-related hammer - a key source of noise on some craft.

WILL IT CHANGE THE FACE OF BOATING?
In short, very probably. As it stands, IPS offers users enhanced manoeuvrability, higher performance and better amenity thanks to lower noise and vibration levels.

For boatbuilders it delivers streamlined installation, in some markets the ability to shed the baggage of sterndrives, and the pluses (and minuses) of dealing with one supplier from steering wheel to propeller.

Price, as yet unannounced, will be a factor. More expensive than conventional technology, consumer acceptance of IPS will require boatbuilders to re-evaluate their costing structures and pass on the infrastructure and construction savings that Volvo claims exist.

That said, the real key to the success or otherwise of IPS will be the enthusiasm of boatbuilders to capitalise on the physical efficiencies the system can deliver - performance for sure, but particularly the packaging efficiencies.

Just as it took the iconic BMC Mini to bring front-wheel-drive cars into the mainstream (and in the process unilaterally change the way small and medium cars were designed and built), the real benefits of IPS will be seen in the next generation of boats designed to capitalise on the drive system's smaller footprint, performance and fuel efficiency.

Set for debut at the London Boat Show as this issue of Trade-A-Boat hit the press, several key manufacturers were expected to debut IPS-equipped boats concurrently with Volvo's public unveiling.

With some of the world's top boatbuilders already onboard (brands such as Fairline, Princess and Sealine in the UK and Tiara and at least two Genmar marques in the USA) the wait to sample these boats fitted with Volvo Penta's latest technology is not going to be a long one.

As they so prophetically say in the classics: watch this space.

When the flag drops How noticeable is the difference in performance between the IPS system and a conventional shaft installation?

Volvo Penta installed IPS and a conventional straight shaftdrive in two identical boats. The craft (two Cranchi 41 Mediterranée sportscruisers) were fitted with twin IPS 500s (D6-370) and twin TAMD63P engines respectively. The engine output was the same in both boats: 2 x 370hp.

TOP SPEED
The boats travelled the same course in both directions and the speed was measured by GPS aboard each boat. The results were:
IPS 500: 37kt
Straight shaft: 31kt

In the test, the IPS boat's top speed was approx 20 per cent higher than that of the same boat with a conventional installation. To achieve the same top speed as the IPS boat, the boat with the straight shaft would need an additional 150hp per engine, according to Volvo Penta's calculations.

ACCELERATION
Both boats began the test at the same time at full throttle from a standing start. The acceleration time needed to reach 25kt was measured with a stopwatch. The results were:
IPS 500: 13.3 seconds
Straight shaft: 15.3 seconds

The IPS boat achieved planing significantly faster and immediately established a considerable lead. The difference in acceleration times was approximately 15 per cent.

FUEL ECONOMY
During the test, the boats were driven at a cruising speed of 30kt and fuel consumption was registered electronically.
IPS 500: 95lt/hr
Straight shaft: 135lt/hr

It should be noted, however, that the TAMD63P engines fitted to the Cranchi 41 do not represent the latest in Volvo Penta's high-speed diesel technology. We'd expect a D6-370 powered shaftdrive craft to perform better.

How much so? That's the $64,000 question. That said, the exercise serves to illustrate the advantages of IPS - advantages that were repeatable across a range of boats sampled.