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Power to the people! 

Are yachts too power-hungry, generators too popular, and engine alternator systems simply inefficient? By Jake Kavanagh

The owner of a very large yacht was overheard describing his recent trip across the Atlantic to a friend.

“There wasn’t much wind, so we motored most of the way,” he said. “We watched DVDs on the wide screen plasma television, played computer games on the X-box, ate microwaved meals from the freezer, and even shared a few boisterous moments in the Jacuzzi. The crew pretty much ran the yacht for us. It only took about three weeks to get across.”

His friend was amazed. “If you enjoy all those luxuries afloat, why waste all that money buying a yacht? You could go first class with Cunard for a fraction of the price!” “Ah yes,” said the owner, “but where’s the adventure in that?”

Whilst researching a feature on power generation for the trade magazine International Boat Industry (IBI) this month, I was intrigued by the way electrical technology is advancing.

The AC power generation on a yacht, especially a large one, has become so sophisticated and refined that now the military are beating a path to the leisure market.

One manufacturer told me that the world’s navies are discarding more agricultural and bomb-proof gensets in favour of the semi-custom kit earmarked for superyachts. “It’s designed to run delicate electronically-controlled appliances and the military need that kind of power for their systems,” he explained.

In fact, with generator sales down right across the world, the interest of NATO and other allies has been a saviour for some struggling companies.

Creature comforts

“Generator sales are usually prompted by women,” remarked the sales manager of one well-known generator supplier. Even though the remark was tongue in cheek, we’ll keep his identity a secret until after the boat show. “Whilst men may still enjoy roughing it aboard, the ladies do like their creature comforts,” he added, bravely. Go get him, Dame Ellen.

However, these hi-amperage comforts can sometimes come at an ecological price. Will peaceful anchorages remain peaceful with a dozen gensets burbling away all night to run the aircon? The MD of VTE in Italy said “We all need to get less power hungry, both ashore and afloat. Electrical systems should be designed to draw less power.”

He has a point, and I suppose we’ve made a start with the rise of the LED. Air-conditioning is probably next.

More deep-cycle batteries

Like it or not, the diesel generator will be with us for a long time, and in increasing numbers as the trend is for more and more smaller yachts to fit a small footprint DC set to top up the batteries.

This has outraged Charles Sterling, the MD of Sterling Power Systems. “Boat builders still aren’t making provision for electrical needs,” he said. I’ve paraphrased his full and frank remarks about the general electrical competence of production boat builders, but he is not alone. Several other suppliers would like to grab the average boat builder by the neck and hug him. Tightly.

“They put in space for just two batteries, one for the engine and one for domestics,” Sterling said. “The yacht can run its systems for about 3 hours at anchor before the skipper has to reach for the generator.

"If boat builders put in a lot more deep-cycle batteries and harnessed the output from the alternator more efficiently, generators would be largely unnecessary.”

Sterling suggests that the average motorboat has a 100ah alternator on each engine, but only about 10ah goes into the batteries. The rest is wasted.

The WhisperGen

Whilst I still shy away from fitting a generator, as I love my cruising to be noise free, one bit of kit that might be on my Christmas list is the WhisperGen from New Zealand-based WhisperTech.

This uses a Stirling engine at its core, and unlike the internal combustion engine, the Stirling doesn’t go bang 2,000 times a minute. Instead, air is gently heated by a diesel flame and then cooled, causing rapid expansion and contraction.

This drives an almost silent pair of cylinders as it cycles from hot to cold. Whilst these are busy spinning up a DC generator coupled to an AC inverter, the heat from the flame also provides hot water and heating.

If the brochure is accurate, it’s a sort of Eberspacher meets Shorepower for about as much invasive noise as a pair of bicycle pumps.

The claimed consumption of 0.75lph is also enticing, but the Stirling engine is bigger, heavier and slower to start than the average diesel engine. Still, you can’t have it all.

The tragic earthquake in New Zealand trashed WhisperTech’s R&D department, temporarily halting progress, but I think they’re onto something...

Jake Kavanagh, marine journalist

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