For most commercial fishermen, the choice of propulsion might be inboard or outboard, depending on the size of the vessel and other considerations, but there are those who choose another option: the outdrive—or stern drive.
“Early on the Konrad 520 stern drive was designed and brought to the commercial fishing market due to the need for a durable and reliable propulsion system. With the 520 stern drive customers were able to see longer service intervals and longer life out of the unit compared to others,” says Josh Schroetter, assistant general manager at Konrad. “As time went on, diesel engines moved into electronic fuel control and higher horsepower driven by consumer demand. To meet the market standards, in 2015, the company introduced the 680B dual propeller, which can handle higher horsepower and heavy vessels.” Schroetter notes that the 680B is often paired with the Cummins QSB 6.7 engine, and is approved up to the 550 hp at 3,300 RPM rating. “With dual propeller technology a single 680B application can efficiently carry 18,000 lbs” he says.
The Konrad sterndrives are usually connected to the engine using marine gear / transmission with a 1.00:1 ratio and reduction is generated within the unit. “We can make it anywhere from 1.2:1 to 2:1,” says Schroetter. “Our application engineers work directly with the OEM’s or vessel owners to determine the best drive ratio for the application. This data is collected by filling out our marine analysis form online which gives us the overall profile of the vessel which would include hull type, loaded weight, type of usage, annual hours, engine rating, and many other aspects of the vessel, propeller size, and gear ratio. We pride ourselves in helping the customer optimize their performance.”
According to Schroetter, the advantage of getting the right fit and eliminating slippage is fuel efficiency. “Our dual prop stern drives deliver 15 percent more fuel efficiency than a single propeller unit,” Schroetter adds that fishermen appreciate the maneuverability that the stern drive provides, especially when gaffing pot buoys or hauling longlines. He reports that most of the units Konrad has sold to commercial fishermen in the Pacific Northwest are going on salmon and Dungeness crab boats up to the 50-foot range. “We’ve also sold some to geoduck divers, halibut fishermen, and local shellfish companies,” he says. “Taylor Shellfish has a displacement vessel capable of moving 100,000-pounds to transport product, but only going around 6 knots.”
In addition to standard applications, Konrad has begun promoting the use of its stern drives with fully electric and hybrid propulsion systems. “We’ve worked with several OEM builders installing fully electric applications over the last 8 years and see a bright future for this option once they can get the battery life increased,” says Schroetter. “Konrad drives have been a great fit for the electric market due to the simplicity of motor integration. Our drives do not have forward, neutral, and reverse shifting in the units, which allows the electric motor to control direction.”
Schroetter brought the Konrad stern drives to the 2024 Pacific Marine Expo in Seattle and plans to attend next year. He invites those interested to check the Konrad website for more updates on when and where to see them.
