HJB launches 'Rainbow'...
She’s the first J-Class yacht to get a hybrid propulsion system. Read all about the system in our exclusive report.
Zaandam-based Holland Jachtbouw (HJB) has launched the ‘new-J’ Rainbow. She is the first J-Class yacht to feature a hybrid propulsion system, which was designed and engineered by WhisperPower/HybridPower. The installation was approved not only by the J-Class Association, but also by Lloyd’s and the MCA.
Beyond efficiency and being able to limit noise and exhaust pollution, the key benefits of this system relate to space and weight savings. Overall the volume savings of this hybrid installation are estimated at around 35 per cent. And the total weight savings over a comparable conventional installation are probably around the 15 per cent mark!
“A conventional power-generation solution for a yacht like this would probably include a couple of generators in the engine-room. But because of the 39.5m (131ft) all-aluminium Rainbow’s 1930s’ race-boat geometry, there simply isn’t room aboard for that sort of installation and all the space and system requirements of a modern super-sailer, which is was she is,” says yard director Tako van Ineveld.
“Initially we looked at a full diesel-electric installation for her, but that would have consisted of two relatively large generators, but that was deemed a little too extreme for Rainbow’s owner... What she’s got instead is a half-way house between conventional and full-diesel electric.”
SY Rainbow has just one generator in the engine-room, an extremely quiet variable-speed 50kVA unit from WhisperPower that’s based on a Steyr diesel and two ultra-compact 512VDC/80Ah lithium-ion (LiFeYP04) battery banks, which are secured in separate compartments. Centre stage is a conventional auxiliary diesel, a 400hp (294kW) Scania DI12 59M. That main engine is hooked up to a conventional shaft and prop. However, a WhisperPower water-cooled 50kW permanent-magnet motor has been added to the Scania’s flywheel that not only delivers ‘quiet-ship’ electric propulsion up to five knots as and when required, which means there’s an extra 50kW back-up for the main propulsion line, but also can serve as a shaft-generator when the yacht is not racing. This later re-generation capability should prove particularly useful when sailing on trans-ocean delivery trips. That shaft generator provides up to 14kW of power. Moreover, the Scania can also be used as a second 50kW auxiliary generator.
One of the big advantages of this installation is the generator only works when it is really needed. If the battery banks are sufficiently full, the generator won’t switch on or will automatically switch itself off. This means the generator only operates at its most efficient loading, which for a diesel engine means around 80-85 per cent. Under-loaded generators are a common problem aboard yachts, because they lead to excessive smoking and reduced service life.
All the DC voltages aboard Rainbow are fed into a fully isolated copper bus-bar (640V) or grid. The generator’s AC output ‒ something around 400-500Hz ‒ is at too high a frequency to be used directly, so it is turned back into DC via water-cooled WhisperPower Hy-Invert inverters and then, where required, inverted again into a usable frequency.
And that DC grid is ultimately flexible. The whole system is essentially plug-and-play. All sorts of things can be hooked up to it. For instance, at some point it could take an extra power input from fuel cells or solar panels; and while the latter may not be particularly practical aboard a ‘J’, a solar component to a motoryacht installation could make a lot of sense.
Obviously there are various system requirements aboard that won’t run on DC supply, so there is also a small AC provision board for cooker, washing machine and drier, as well as the air-conditioning compressor... And actually the hydraulic pump aboard will also run on AC, simply because that was the cheapest way to do it.
Most of the time the on board 230/400 VAC consumers, including the air conditioning system, will operate through via one 35kVA Vacon inverter.
Indeed, the system has been designed to deliver up to eight hours of ‘quiet ship’ overnight, which would probably mean programming for something like 23.30-07.30. But such things will depend on the power demands; with unusual demands it would be more or less.
And there is considerable scope for quiet sailing. Not only does the all-electric capability extend to leaving a berth or anchorage and hoisting sail without firing up either the main engine or generator, but also to general sail handling. It is quite conceivable that she could cope with a day-race without firing up any diesel. In all she has up to 70kW of hydraulic power available off the batteries, which is a lot, but then there is a lot of hydraulic work to be done aboard a modern J, albeit usually in short bursts.
The downsides to this type of hybrid installation are really cost and safety.
Overall, battery banks included, the HybridPower installation aboard Rainbow was perhaps 15 per cent more expensive than a conventional engine and generator set-up, suggests Arjen Zijlmans, HJB’s engineering director, but it will prove cheaper to run. He suggests the break-even point will be around 2,000 hours when marine diesel reaches €3.00 per litre, although that calculation doesn’t account for the extra quiet-time sailing that can be done without engines running.
The safety issue is all about training those aboard to be very mindful of the precautions associated with high voltage DC power; but then shore-power systems these days work this way too – converting from AC to DC and back to AC, so most captains and engineers are familiar with the issues.
Actually maintenance couldn’t be much simpler with the Rainbow system. And, providing everything is looked after properly, her battery banks are covered by a seven-year warranty. Mistakes can be costly. Running those batteries flat, for instance, would effectively destroy them.
Initially this HybridPower system was to be developed under a joint-venture arrangement between HJB and WhisperPower, but down the line the latter specialist took over the initiative completely, although there was necessarily plenty of input from the yard’s technical team and some of the key component suppliers on this first installation.
WhisperPower maybe a relative newcomer, having only been founded two years ago, but its experience is considerable. The man behind the business is Roel ter Heide, who with brother Ferdinand was responsible for building up Mastervolt until they sold out a few years or so ago. WhisperPower has not only put together its own power-product portfolio, but also manufactures various items for the likes of Mastervolt at its impressive purpose-built facility just outside Drachten, Friesland.
Beyond all sorts of interest from the commercial vessel side of the industry, Roel ter Heide says he sees WhisperPower’s core HybridPower yacht market being around 30-60m (98-197ft), power and sail. “But it is early days for this technology,” he says. “It could well be that the sub-30m (98ft) market opens up to be even bigger for these sorts of installations...”
“Looking to the future, I predict there will be hybrid aspects of most new-builds,” says Martijn Favot, project manager for WhisperPower’s HybridPower initiative. “As fossil-fuel supplies diminish, the price of fuel will continue to rise; and fuel efficiency will become ever-more important... So I say it will be goodbye to space consuming, noisy and energy inefficient diesels that run round the clock, pollute the environment and require costly maintenance... The interest in green solutions like those offered by Hybrid Power can only increase...”
SY Rainbow, which carries sail number JH2, is a Dykstra & Partners Naval Architects translation of the original William Starling Burgess designed yacht of the same name. Gerry Dijkstra and team have been involved in the new-builds/re-builds/refits of several other ‘Js’ ‒ including Shamrock V, Endeavour, Velsheda, Ranger and Hanuman.
After her sea-trials and commissioning, the plan is for Rainbow to take part in the various J-Class regatta events that are planned for this summer to coincide with the London 2012 Olympic Games. She will be available for charter almost immediately.