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Yes, I attended the 2018 International Boatbuilder’s Exhibition, in Tampa, Florida. And yes, I found plenty of innovative technology to tell you about. However, it’s probably not what you expect.

I’m not going to tell you about the latest trends in fender clips, or the newest, baddest LED underwater lighting array, or any of the items that won awards for innovation this year. Instead, I want to go deeper and tell you about a group of distinct technology waves coming together in a synergistic swell that will change the way you generate and manage onboard electrical power.

A Chilling Revelation

Traditionally, the single most significant factor in a yacht’s total electrical loading has been the current demand produced by its air conditioning system. That’s because starting a traditional a/c compressor motor draws five to seven times its normal running current. Moreover, these traditional single-speed, induction-type a/c compressor motors have only two running states: on and off. The level of cooling action in a system using such compressors is modulated by turning them on for a length of time, then off for a length of time (not necessarily the same length), then on again, then off again, and so on and so forth, ad infinitum.

Webasto’s BlueCool V-Series chiller systems employ variable-speed digital inverter type A/C compressors. Draw is 10 percent less than that of more traditional systems. 

Webasto’s BlueCool V-Series chiller systems employ variable-speed digital inverter type A/C compressors. Draw is 10 percent less than that of more traditional systems. 

If demand for electrical current spikes significantly every time a traditional compressor starts, imagine what happens on those yachts that have half a dozen or more compressors in their a/c system. In a multicompressor system, if several compressors happen to start at the same time, the current spike can be enormous—so high, in fact, that it becomes necessary to size the yacht’s generator at twice or more the output that would otherwise be adequate to carry the yacht’s full electrical load.

Enter the variable-speed digital inverter a/c compressor, which has come to the forefront of the market of late. Rather than stopping completely, these compressors merely slow down as demand on the a/c system for cooling drops. As demand for cooling rises, these compressors ramp up their speed in proportion to that rising demand. Most importantly, the current draw of variable-speed digital inverter compressors doesn’t spike because these compressors are not tasked with going from a completely inert state to full run in an instant.

At IBEX, at least two exhibiting manufacturers of a/c systems were using these variable-speed digital inverter compressors: Webasto, with its BlueCool V-Series chiller-based system, and Termodinamica, with a highly efficient direct-expansion system approach. Both systems exhibit exceptionally low current demands, whether starting or running; in fact, they require less starting current per ton of cooling capacity than traditional single-speed compressors, with an average ratio of 1:14. Make no mistake, that’s a game-changing difference when it comes to supplying electrical needs on board. Hold that thought.

An Electrifying Idea

Holland, Michigan–based firm Volta Power Systems has introduced to the marine market electrical generation and storage technology from the automotive and recreational vehicle sectors. Key elements of these systems are an automotive-type high-capacity lithium nickel manganese cobalt oxide (NMC) electrical storage pack (battery) in capacities up to 96 kWh; a line of high-output propulsion-engine-mounted alternators in three models with output from 6 kW to 11 kW at 58 VAC; and a continuous-rated pure sine-wave inverter with a continuous output of 3.6 kW and surge capacity of 6 kW at 120 VAC.


You don’t need to wrestle with all these numbers to understand their basic significance. Let’s just say that it’s now both possible and practical to run one of the new variable-speed inverter compressor a/c systems, in a 5-ton configuration, for more than 300 hours (13 days) on battery power. Also, the amount of electrical energy required could be generated and stored while running a yacht’s main propulsion engines in less than 5 hours—roughly the time it takes to cruise from Bimini to Nassau.

What It All Means

Combining the two technologies makes it possible to bring true hybrid power to ordinary cruising yachts. With the right off-the-shelf equipment, running your genset overnight could become a relic of the past (or in any case a rare occurrence as opposed to a nightly ritual). At the very least, I imagine we’ll see a trend to downsize gensets in a major way. Understand, we’re talking about proven technologies that already exist. It’s surprising that we’ve not yet seen these two technological threads melded on a regular basis. I wanted to highlight this potential advancement for cruising yachts, since it didn’t seem to get the hype I thought it deserved last year at IBEX.