Test day dawned hotter than hell, as if to underscore the gloom of global warming. The National Weather Service heat index for our testing venue—Beaufort, South Carolina—was predicted to peak near 112F. At eight o’clock in the morning, Abraham pulled into the sweltering parking lot of Lady’s Island Marina in a CMD pickup truck with tank of B20 in the back. Chris Butler of Butler Marine, Glacier Bay’s local dealership, arrived almost simultaneously, and so did PMY photographer Martin Simon and me.
We set to work immediately, offloading B20 into five-gallon jugs and lugging them to our 3470, Smooth Ice. As the morning wore on, folks hanging around at the marina began exercising their curiosity. I explained that PMY had purchased a drum of soy-based B100 for $4.13 per gallon from West Central, a bulk distributor in Ralston, Iowa; that CMD had converted the stuff into B20 in Charleston; that B20 was obtainable at many gas stations in South Carolina and indeed across much of the country; and that “the warranty thing” and other issues should be investigated well before pumping B20 into a diesel-powered vehicle.
We did the wring out on the Beaufort River over a period of three hours. During that time a slowly ebbing tidal current remained unchanged, and the wind stayed variable and light. There were four of us onboard for the first, regular-diesel-fueled portion of the test but just three stayed onboard for the second, B20 portion. Fuel load for the B20 portion was also a bit lighter due to the consumption during the earlier regular-diesel runs. Taking into account the hefty 18,700-pound dry displacement of the 3470, however, we calculated the difference in test-boat weights—regular vs. biodiesel—at just 250 pounds, giving only a slight advantage to the latter fuel.
Results were intriguing. Performance differences between the two fuels were so small (see test data, this story) as to be immeasurable with PMY’s test equipment. Basically, we got the same speeds, the same fuel burns, and the same acceleration curves, disregarding operator-error-generated differences in starting speed. Butler and I drove the 3470 with both fuels coursing through her mains, and neither of us could quantify any handling differences whatsoever. B20’s only distinction was its total lack of smoke and smell! We were all big-time impressed.
Sure, biodiesel’s got its drawbacks at present, things like a reported six-month shelf life; the tendency of high concentrations to break down rubber fuel hoses and gaskets on older engines; availability problems; and the aforementioned warranty issues. But engineers are developing shelf-life-extending additives; modern engines from Cummins and others typically have synthetic gaskets and hoses that won’t break down; availability’s on the rise; and the marine industry’s stance on warranties may change as standardization solidifies and the cost of regular diesel skyrockets.
More testing is needed, of course. A one-day wring out of one boat is not definitive, especially when shelf life and other stumbling blocks may surface only after lengthier periods. Nevertheless, right now, I’d say B20 works! In the real world. On real boats.
We proved it.
This article originally appeared in the October 2006 issue of Power & Motoryacht magazine.