"For me, it was always wanting to be on the water," says Bob Dunn, captain and owner of Moonshadow, a 29-foot Ocean he charters out of Penna’s Marina in Beach Haven, New Jersey. "And as long as I was making that decision, I decided I was going to do it right and within my means."

Dunn is a charter fisherman who along with his son Bob, Jr., operates his boat from spring to late fall. While most of his business comes from half-day family charters, he looks forward to canyon runs for white marlin and tuna during the summer months.

He says he first saw Moonshadow in 1998 and decided she was the perfect vessel for his needs. "She had a pair of 350-hp [gasoline] Crusaders with very low hours on them," he recalls. "The boat cost me $65,000, and I fished her all that season and was getting killed on fuel costs. When I put her up on the hard after my second year, I knew I needed a pair of diesels if I was going to make things work."

Dunn came to his decision with engine-swapping experience already in his wake. He’d replaced the 85-hp diesel in his previous boat, a 29-foot Prairie trawler–which he had for 20 years before buying Moonshadow–with a 200-hp Perkins diesel. He did his homework all winter, attending most of the boat shows and finally decided on a pair of 300-hp Yanmar 6LPSTEs. "Price, weight-to-horsepower ratio, engine size, range and fuel consumption, application, trade-in for my engines, resale value, and finally reputation were key factors for me," he says.

Dunn says the price tag for the Yanmars came to $38,751 (with Crusader trade in), including Hurth 630A1 2:1 ratio down-angle gears (unlike the Crusaders, these diesels would be installed flat), engine mounts, 80-amp alternators, couplers, wiring harnesses, L-type mixing elbows, and freight.

With that decision out of the way, Dunn sought out a yard to do the installation. "It’s crucial to get the right team for the job," he warns. "Time is money, and when you’re a working stiff like me, $75 per hour for a decent mechanic takes on more meaning. The last thing you want is someone without a plan." For him, the decision was easy. Steve Westberg, Penna’s yard foreman and head mechanic, had done the Perkins exchange on the Prairie, and Dunn had been pleased with the way that job came out.

To keep costs down, Dunn did most of the grunt work, unhooking the old engines, readying the wiring harnesses, hoses, and Racors, draining the tanks, and doing some minor fiberglass and duct work. Once the Crusaders were removed, Westberg fashioned new beds, boxes, and engine vents.