Say goodbye to the most popular re-powering engine in history. The Yanmar LH series four-cylinder engine has earned a reputation for quiet running, but it’s making its exit with a bang. The last ones off the assembly line are expected to sell briskly—as you might expect for a motor often described as “the sweetest,” “bulletproof,” “dynamite” or just plain “unbelieveable.”

The four-cylinder LH was first introduced in 1988 and comes in 160, 200 and 240 horsepower packages, but the marine engine fraternity refers to them all as “the 240.”
The 240 (and its six-cylinder sibling, known as “the 315”) caught the wave of sportfish conversions from gasoline to diesel power as marine diesel engines began improving dramatically in the 1980s. In repowering, size matters but so does shape. Yanmar accounts for more than half of all diesel re-power projects in North America in part because Yanmar diesels simply fit better than Caterpillars or Cummins in some machinery spaces designed to house prevalent gasoline engines.

“Higher torque diesel engines mean that a 240 or 315 can replace gasoline engines of nominally higher horsepower with an increase in efficiency and performance,” said Richard Mastry, vice president for sales at Mastry Engine Center of St. Petersburg, Florida, Yanmar’s distributor for the Southeaster U.S. “They’re inline fours and sixes and fit easily into the footprint of the gasoline driven V-8s that dominated the medium sportfish market.”

With the optimum gear ratios and propeller dimensions, vessels owners were often able to get their old boats to go 20 percent faster burning half the fuel. That meant, for example, that a vessel that once cruised 18 to 20 knots with gasoline engines was now thundering along at up to 25 knots with diesels.

Mastry and Mack Boring of Union, New Jersey, distribute all the Yanmar marine engines on the East Coast. Both are marking the demise of the 240 by ensuring an ample supply of these LHs for customers right up until the end.

New federal emissions rules have set lower limits on the emissions from marine diesels, and these are being enacted in stages over the next three years. The 240 and 315 are what mechanics call “mechanicals,” meaning that fuel is pushed to the cylinders by a gear-driven injection pump.

Yanmar’s replacement for the 240 is a collaboration between the Japanese engine-maker and BMW of Germany. The new BY engines are beautiful to look at, but more importantly they are not mechanicals; they are fed fuel through an electronically controlled “common rail” delivery system that measures out diesel more precisely for a cleaner burn.

Four-cylinder BY engines are available in 150- and 180-horsepower packages. The six-cylinder BY will also offer two packages, either 220 or 260 horsepower. They cost about $3,000 more than a comparable 240.

The two generations will briefly overlap. The BY and 240 are both for sale at this writing, and production of the mechanical 240 will cease at the end of this year with availability expected through spring 2007.

The 240s were fast turning motors in their day, at a maximum rating of 3300 rpm’s, but the BY revs even higher, up to 4000, which optimizes its performance when coupled to a stern drive. Yanmar hopes that these new and ever lighter weight engines will extend the re-power market to include smaller vessels such as ski boats.

“A lot of people are going to want the BYs, too,” Pat McGovern of Mack Boring said. “But initially there’s going to be a surge in sales of mechanical engines. A lot of people in the marine industry don’t like change, and the LH has a proven track record. It’s a dynamite engine.”

Eddie Johnson of Johnson’s Boat Works in Cranston, Rhode Island, has re-powered about 300 boats since he got into the business six years ago. Johnson said the cost of re-powering with diesel engines usually ranges between $65,000 and $120,000 depending on engine horsepower and the complexity of the conversion. Johnson has no doubt that the new electronic motors will prove every bit as popular as their predecessors. Even the added cost is unlikely to affect the trend toward diesel conversion, in his opinion.

At this writing Johnson is in the midst of two Yanmar re-power projects—a 1989 Black Watch diesel-to-diesel job and a 1986 Blackfin gasoline-to-diesel conversion. Surely many owners faced with the expense of installing new engines will seriously consider buying a new vessel instead, but that was not the case with the owners of these vessels, both of whom are from Massachusetts and both of whom have boating in their blood.
David Curtis of Marblehead said he “hates to fish.” Ever since he bought his Black Watch six years ago, he’s been upgrading the 29-footer for service as a fast trawler for cruising the Maine coast. The old diesels were too loud, smoked too much and vibrated to beat the band. Curtis didn’t want a stinkpot.

“The boat looks so good the only thing that would make it perfect would be to have new smooth running engines that don’t pollute,” Curtis said. He’s getting twin 315s.
For Peter Sheer of Norwell, who does like to fish, converting to diesel would mean more offshore runs to hunt tuna with his family. He’d fished the boat for 18 years when it belonged to his father-in-law, and now the Blackfin 29 is his. He is as happy as a man can be that his boat is getting Yanmar 370s.

Even though neither boat’s conversion involves the soon-to-be-gone 240, both illustrate the fact that though re-powering adds value, it rarely adds enough value to “pay for itself.” Although with today’s higher gas prices, there are some fiscal considerations. In a world where money and love are two great motivators, re-powering projects likely belong to the latter, it being a provable fact that people do love their boats. Plus, a re-power also increases the reliability and peace of mind factor.

Which is why those faithful ticking hearts, known as the 240s, have earned the affection of a generation of powerboaters. Contact: Mack Boring, (800) 709-0672; www.mackboring.com; Mastry, (800) 545-4574; www.mastry.com.