The hum of a diesel engine is a sweet sound to a fisherman’s ears. Recently, the owners of the 48-foot Mack Attack emptied the fuel tank of its petroleum diesel and filled it with RD99, a biodiesel refined from cooking oil and animal fats.
From idle to wide open throttle, the biodiesel performed on par with petroleum-based fuel.
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“We were really excited to see that there was no fall off on power anywhere, acceleration, maneuverability with the boat,” Dennis Glynn, the Mack Attack’s captain, told Straight Arrow News.
The sea trial team from Viking Yachts and Mack Boring & Parts Co. purchased the RD99 for $5.57 a gallon. Petroleum diesel’s nationwide average is $3.74. The marine industry is exploring the use of biodiesel as its primary fuel and hopes the nearly $2-dollar gap will narrow to 20 cents.
What is RD99?
RD99 is a plant-based fuel, which adds less carbon-dioxide to the environment than other options.
“When you’re burning fossil fuels, you’re digging up fuel that’s basically been sequestered for thousands of years, and when you’re burning it you’re releasing new CO2 into the environment,” said Patrick McGovern, president of Mack Boring, a marine and industrial engine distributor. “So you’re basically adding to the problem with traditional diesel fossil fuels.”
With hydrotreated vegetable oil like RD99, McGovern said, “you’re basically recycling the CO2.”
The biodiesel is physically and chemically similar to fossil-based diesel. It can reduce greenhouse gas emissions by 70% to 80% compared with petroleum.
“They’re actually a much cleaner burning product, less particulate,” John DePersenaire, Viking Marine Group’s director of government affairs and sustainability, told SAN. “So in theory a lot of the preventive maintenance, things like filters and injectors and things like that, they actually should be better under these products than under traditional ultra low-sulfur diesel.”
What are the challenges associated with biodiesel?
The problem, in addition to cost, is supply.
In 2024, the United States had a production capacity of about 2.1 billion gallons of biodiesel a year. That’s for everyone — not just boats. The marine industry alone uses about 87 billion gallons of fuel annually.
Viking Yachts, the top producer of sport fishing vessels, is working to help marinas and boat owners adopt this fuel. The industry is hoping for funding and subsidies from the federal government to increase production and bring down the price.
“With there being greater scrutiny and concern about emissions and things like that, we’ve been trying to find ways we can address those issues but also accommodate our operational needs,” DePersenaire told SAN. “We need to go far, we need to go fast, that is just a basic principle of recreational boating.”
Marinas have the added challenge of making space and getting permits for the holding tanks.
The Department of Energy sees these types of fuels as the predominant energy source for commercial fishing boats, ferries and high-use, non-commercial vessels by 2050.
“We would love to see the Department of Energy, Transportation, collaboratively work together and find ways of ramping up refinery capacity, working on distribution, getting these fuel products out into areas like this,” DePersenaire said.
They also hope there will be incentives for diesel-burning truck fleets.
“Because once we start getting fleets like the UPSs, the Amazons, the FedExes of the world starting to use these products as well in their gas and diesel trucks, we will start to get the benefits of that distribution network,” DePersenaire said.
Biodiesel as an easy solution for clean power
Sportfishing yachts are massive and require extraordinary power. For instance, the 90-foot Viking weighs 192,000 pounds and commands twin-engines with a total horsepower of about 5,200. The boat has a 3,800 gallon fuel capacity, and burns more than 150 gallons of fuel per hour at cruising speeds.
Because of the sheer size of these vessels and the distance they travel, they require combustion engines for propulsion.
“The battery applications that would be needed to be used to power a source like this to go 100 miles offshore would basically be the size of the engines at this point in time,” Glynn said.
The weight and size make batteries prohibitive.
The RD99 is what’s called a drop-in: It requires no new parts or special maintenance; a boat captain only has to open the gas cap and fill the tank to make the boat more environmentally friendly.
“What we love about these drop-in sustainable marine fuels is that you can have an immediate effect on not only new boats, but the legacy fleet as well,” DePersenaire said. “So you can have a 30-year-old, diesel-powered boat that’s in a marina, that’s a smoker, you start to bring in sustainable marine fuels and that boat is almost instantly retrofitted.”
Viking owners can spend $5 to $10 million or more to buy their boat and the yearly maintenance is usually about 10% of the purchase price. The owners have some of the biggest pocketbooks in the world. Even still, DePersenaire said he believes government subsidies for environmentally friendly fuel could offer a key solution.
“We all want to do our part to minimize our impact on that environment. Because if that environment is degraded, if the resources aren’t there, if the fish aren’t well managed and sustainable, then we’re not going to be selling boats for people to go fishing,” he told SAN. “So I think inherently, our industry has a very keen interest on working towards this.”
