DC Power

A current affair

About 15 years ago, Bill Clinton pushed a button that gave GPS reception to the world's public. General aviation, 4WD and boating were among the many recreation groups to benefit from this unique technology.  For the boating public and boat manufacturers, new technology brings immense opportunities from lowering production costs to miniaturisation, subsequent space and weight savings, and new ways of doing things.

Take, for example, the humble marine generator of yesteryear, say a 6kVa model probably manufactured around 1980 and found in many of the older Riviera cruisers, Mariners and trawler-style boats. These gensets were probably based on a two or three-cylinder Kubota-type engine which did a good job of providing power for AC systems and battery charging.

But these older-style generators took up a good amount of space in the hold, their position often made them difficult to service, and they weighed about 180kg on a good day. They were also relatively noisy, as modern sound-insulation materials had not been developed.

A NEWER WAY
Today's gensets are far quieter and more compact but they still weigh about the same. And if you want 240V power on tap while you are swinging on the anchor or underway, a modern generator will set you back about $12,000 to $15,000. So, is there an alternative when the old faithful gennie fails? Do you replace it with the same kind of beast or is there new technology waiting in the wings?

Rightfully, many owners are investigating the installation of inverters, larger battery banks using 6V deep cycle batteries, converting from 12 to 24V house banks, as well as solar panels and smaller DC generators. This brings me to my 1982 model Mariner 43 equipped with the original 6kVa Onan genset which simply keeps on going. It's always serviced and has done 2600 hours to date and seemingly without burning a drop of oil.

And my gennie can be a godsend. During a winter week with my family to Broken Bay, it was so cold and wet that to keep warm we used the genset for eight hours a day to power a domestic fan-type radiator. This probably cost us $100 in diesel, not to mention the constant engine rumble throughout the boat. The genset also replenished our house batteries and heated the 50lt hot-water tank. During summer weekends, the genset is run to top-up the house batteries, for hot water, the BBQ and stove/oven, and to run the dishwasher twice daily.

So my Onan gets a good workout and is testimony to the longevity and popularity of this brand. While I am probably an AC junkie at heart, being in the marine game allows me to test all the products my business sells. I've also been able to assess new power systems. To this end, I am the beholder of some good news: a large boat does not necessarily have to rely on an AC generator for hours on end.

Here are some pointers and tips on how to reconfigure your older cruiser from a generator-reliant home-away-from-home to a smarter boat aboard which you need to start your gennie just a couple of times a day. If nothing else, your neighbours will love you for it.
 

CONVERT TO 24V
Convert all pumps and lighting to 24 volts. Cost? Let's say $500 for pumps and $40 for incandescent globes and $200 for halogen globes. White light LED interior lighting is becoming available in cool new styles. Keep a look out for these energy efficient beauties as they hit the market.

TRY SOLAR
Install a 160W 24V solar panel on your flybridge roof or front deck. Connected to an intelligent solar regulator, this system can theoretically add 40 amps to your 24V house bank during sunny days afloat. That's enough to run a fridge on a low setting 24/7 through a Sydney winter. I kept steaks in the freezer for one month to prove the point... and I ate them, too. Cost? No more than $1800 for a system that won't let you or your barbie down.

THE SMART MONITOR
Install an intelligent battery monitor, which shows you amps used, volts and the remaining power in your batteries. This little device will tell you when your batteries are full and, thus, you know when you do not need to run the generator. It also shows the effectiveness of the solar panel, your new engine 24V alternator or wind generator, but more on them below. Cost? Say $350 for a good battery monitor.

PURE SINE-WAVE
Look at quality pure sine-wave inverters that have a reasonably high continuous output. A kettle requires 2200W of power to operate, which equates to near 9amp. The continuous rating is important, as the transistors inside that convert from DC to AC, have reduced output as their temperature rises. Cost? Jaycar has 2000W inverters for $700 or so, whereas an industrial/factory-type 2000W inverter will set you back about $2400.

DC POCKET DYNAMOS
Look at DC generators as an alternative to the ubiquitous AC models. Such units are tiny by comparison, they might weigh 40kg or less, and they might have an output of up to 50amp at 24V to charge your batteries. When combined with a larger battery bank and decent high-output pure sine-wave inverter, there are significant space and weight advantages, especially for cruising yachts that traditionally have never had a genset. Modern boatbuilders who regularly install twin gensets in larger boats could now install one AC genset and one DC genset saving space and cost. A DC generator costs about $5000. (Ed: Stay tuned for more on DC generators).

Last but not least, consider the conundrum faced by Sydney-based Halverson boat fanatic, Tony Mackay. His magnificent 56ft flybridge Sinana (circa 1975) came from its original owners with 12, 24 and 32V systems. The 32V side is for the engine starter motors and the circular spinning windscreen wipers also found on ships of the day.

Eventually, when Tony's handpicked sparkie is finished with his beautiful Halvorsen renovation, the boat will be entirely 24V with just the simplest of 12V systems for the radios, must-have iPod and, I'll let you in the on the secret, his mini wine chiller. Cheers, without the usual the chugga chugga chugga...

* Scott Fuller is a boating enthusiast and principal of a Sydney-based marine distribution business.