Gen Z boaters may never cross paths with a genset. That prediction, of course, assumes that those just coming of age will go boating at all, but technology is quickly emerging to replace the marine generator with pollution-reducing, experience-enhancing options that attract post-millennials.
Advances in battery technology during the past decade have made it possible to daisy-chain a bank of cells that can store enough power to run a boat’s electrical systems — televisions, the microwave, A/C and more — for at least eight hours. No noise, no vibration, no fuel burned. When the day at the sandbar is done, the system recharges using the engine alternator.
“An awful lot of people want to hang on the hook and run the A/C overnight without running a generator,” says Nigel Calder, an author and consultant for Ocean Planet Energy in Bath, Maine. “That requires a large pack of deep-cycle batteries, but it’s possible. People are deciding that it’s better to have a larger alternator than a generator.”
Phil Gutowski, the owner of BoatRx, a North Miami Beach company that designs and installs custom battery-bank systems, says the future is about larger boats having more options and smaller boats having options to use equipment they previously couldn’t. “Those midsize cruiser-type boats — say 45 to 70 feet — can run everything without having a generator,” Gutowski says. “And boats in the 20s and 30s can get systems that they haven’t really had before, like air conditioning.”
Generators limit those options because they need to be sized for a theoretical maximum load. A boat with a lot of electronics on board would need a big generator, which adds weight, takes up space and makes noise while burning fuel. And regardless of the energy load, the generator operates at full power. Plugging in a few phone chargers while listening to the radio requires the generator to run as if someone were blow drying their hair while cooking a turkey in the microwave.
“With stored energy, we can draw only the power we need at any time,” Gutowski says. “Battery banks are almost eight to 10 times lighter per amp hour, smaller overall and modular, so even a system sized for max output can fit in smaller spaces.”
Calder adds that, in the past 10 years, the energy density of lithium-ion batteries has increased 30 percent. Gutowski says many battery-bank installations are using a lithium-iron-phosphate (LiFePo4) combination because it’s “stable, tested and has a good safety record.”
But improved batteries are not the only technology driving change. Variable-speed A/C systems that use 50 percent as much power as traditional setups have spread far and wide on RVs but are just finding their way into the marine world. These high-efficiency units come in 24- and 12-volt versions that run up to 12,000 Btu, making them a great mix of size and efficiency for smaller installations.
Good systems, Gutowski says, not only include a series of high-efficiency components, but also manage energy use and integration. “This whole thing is driven by battery technology and innovative thinking,” he says. “Our job is to understand a boat’s needs and figure out how to store enough energy and move it around the boat.”
With that in mind, Wakespeed Offshore in Anacortes, Wash., has built an alternator-regulator system that prioritizes integration. The WS500 can detect battery voltage, amp flow, and alternator and battery temperature, even as it communicates with the engine and battery management system. It automatically identifies system voltage and adjusts to support 12-, 24- and 48-volt arrangements, and it works with eight battery types, from lead-acid to absorbent glass mat.
“There’s so much energy going around a boat that you have to control it well,” says Al Thomason, a co-founder and partner at Wakespeed, which has a large presence in the RV market. “Our goal is to allow the deployment of an efficient system while protecting the batteries and alternator.”
When subtracting a generator from a boat, adding a bank of batteries is only half the solution to the equation. The other half is adding a high-output alternator. BoatRx often uses an alternator that’s the equivalent of a 7kW to 9kW generator, and that runs off the main engine, even at low rpm.
Thomason says he’s worked with installations in which a 5kW or 6kW alternator combined with a battery pack allows a boater to run systems for the better part of a day, then recharge during a few hours of cruising. “Boats in the upper 20s to 30s are similar to RVs,” he says. “They can run the A/C all night, then idle the engine for 30 minutes in the morning and be set for the day.”
Most systems are set up with a separate battery connected to the starter, so even if the bank runs down, there’s power on board to fire up the engine and recharge.
The need for a larger alternator means battery-bank systems currently work better off an inboard, since outboards don’t have the space or ventilation to bolt on a bigger piece of equipment. In some applications, installers leave the main alternator in place and add a second alternator to feed the battery bank, a setup that allows for variable loads. “These systems are perfect for inboard-powered boats that spend time at anchor,” Gutowski says.
That’s not to say that outboard boats are excluded from having these types of systems. When Sea Ray set out to design its SLX-R 400e, it wanted to build the boat around cutting-edge technology that improved the boating experience. Brunswick Corp.’s 2018 acquisition of Power Products included Mastervolt, a company that had already developed a battery-pack system, giving Sea Ray an in-house option.
The company also had access to the new Mercury Racing 450R, which comes with a 115-amp alternator, a decent jump up from the more typical 70 amperes available on most large outboards. The resulting system, with four lithium-ion batteries, generates 22kW and can run everything on board — air conditioning, grill, hot water heater and more — for eight hours on a single charge. Sea Ray worked with Simrad to integrate a bar graphic that shows unused power remaining and the time until full battery discharge.
The system is scalable up or down for other boat models, and Sea Ray plans to make it available to OEMs. Still, when it comes to outboards, someone will have to solve the problem of alternator size. “We continue to work with Mercury to find more charging power,” says Sea Ray director of North American sales Ritch Ragle. “If the demand is there, it will be worth their effort to figure out a way.”
Generators remain useful equipment and won’t disappear anytime soon, but considering what battery-bank technology has to offer, demand for new systems shouldn’t be a problem. “We’ve long known we were only using about 50 percent of the theoretical power batteries offer, but it’s about to take off,” Calder says. “Watch this space over the next 10 years.”
This article originally appeared in the May 2020 issue.