The first time I went aboard the Marlow Explorer 70E Mark II, she was tied up next to the Rod and Reel Club on Miami’s posh Hibiscus Island. It was late, with a boat-show party going on, and the feeling under the live oaks was pure nautical romance. Lanterns on the dock sent a soft, mandarin-orange glow into the dark, warming the 70’s glossy blue flanks and cream-colored superstructure.
Nautical romance is a tad distracting, I guess. One way or another, I failed to notice (until Marlow Marine founder and honcho David Marlow made mention of the fact) that this particular 70 was subtly unlike any other launched since the model’s debut some seven years ago. “We’ve made a few modifications I think you’ll find interesting,” Marlow said with a grin, touching the brim of his signature straw hat.
He lead the way topside to a spot just below the trailing edge of a redesigned hardtop with fixed windshield panels forward and removable enclosure curtains on either side. Then, displaying an agility common to seafarers the world over, he jumped up onto a thigh-high, molded-fiberglass deck box and invited me to do the same. We gazed for a moment at an enormous 140-square-foot solar array I’d not seen from the dock. He explained that it consisted of eight, mono-crystalline Suntech panels (made with a type of sand specific to the Gobi Desert), each integrated into a long, rectangular whole. “The world’s changin’ fast, Bill,” Marlow said, once we’d both jumped back down, “and folks who don’t change with it are gonna fade away like the dinosaurs.”
We then talked solar power for a bit, a flavor of alternative energy that’s evolving at an arguably explosive rate today. The 70 beneath our deck shoes, Marlow enthused, was the first in a series of Marlow Explorer Mark IIs (from 53 to 86 feet) that will use solar and other green technologies to bolster efficiency and environmental friendliness. Toward the end of the confab, I suggested (with characteristic impulsivity) that we check out the real-world capabilities of the first avowedly green Marlow Explorer by giving her a conventional sea trial and then spending a fully refrigerated, fully entertained, amply lit night onboard, in some quiet anchorage some place, without cranking either of her two Northern Lights gensets.
Marlow agreed. And just a month or so later we again met onboard the 70, but this time near Marlow Marine’s facility on Snead Island, a sequestered slice of Old Florida bordering the Manatee River, south of the mouth of Tampa Bay. While speeds, running attitudes, fuel-burn rates, and other aspects of performance are available elsewhere (see “How Does A Solar Boat Perform?” this story), Marlow and I spent a lot of time focused on exactly what makes the 70 swifter, more fuel-efficient, and greener than her predecessors.
Weight came up first. At his plant in Xiamen, China, Marlow continues to develop one of the most sophisticated resin-infusion processes in use today: RIVAT (Resin Infusion Vacuum Assisted Transfer). But while RIVAT has been applied exclusively to hull construction since its inception, Marlow’s now using the technique for both the Mark II 70’s hull (including skin coat, coring, and all laminate layers) and her stringers. Moreover, Marlow expects that future Mark IIs will add major bulkheads to the mix. “Not only does one-shot infusion simplify lamination and prevent secondary bonding failures,” he explained, “but it removes substantial weight and improves efficiency and performance.” Squeezing excess modified-epoxy resin from the 70’s hull and stringers with RIVAT, he added, cuts her weight by approximately 1,700 pounds, a hefty number, considering all the other weight-saving measures employed like cabinetry cored with Plascore and granite countertops backed with aluminum honeycomb.
Hull form was the next subject. From the start, Explorers have had beam-to-length ratios that differed only modestly from gunwale to waterline. But the Mark II series is subtly changing all this; the waterline beam of the 70 has been reduced from the original by 1'3". The point, Marlow told me, is to boost operating speeds and efficiencies by narrowing the running surface, thereby cutting skin friction-related drag. “And the weight we save with infusion and coring materials,” he added, “nullifies the loss of buoyancy we get from slightly shrinking the underwater hull form.”
Solar power was the final subject we talked about during the sea trial. And we continued discussing it, off and on, well into the evening once we’d dropped the hook east of Emerson Point. “While this system’s simple compared to what we’ll have in the future,” said Marlow, “it’s still got three rather complicated parts.”
The most critical (and at $15,000, the most expensive) is the solar array itself, an optional addendum rendered almost invisible by its low-profile location on the hardtop. Each beefy aluminum-frame panel in the eight-panel array is roughly 3'x5', mechanically interlinked with the others, and capable of an approximate 175-watt maximum output (35 volts x 5 amps). Adding the eight separate outputs together pushes the array’s total oomph to roughly 1,500 watts (1.5 kW), well over the 1,400 watts the 70 typically consumes while underway, according to Marlow.
This article originally appeared in the June 2009 issue of Power & Motoryacht magazine.