Bryan Tuvell 33ZX
11-06-2001, 05:33 PM
You're in your friend's new tender, a Donzi Classic 16, running toward shore from his anchored yacht at a comfortable 33 mph, when he casually mentions that the boat is out of gasoline. Before you have time to panic, he explains that that's because this boat doesn't run on gasoline. She's diesel-powered, which, he points out, means he doesn't have to carry gasoline onboard his yacht; he can fuel the Classic 16 right from his yacht's main diesel tanks.
This boat is real, and so is her performance. In fact, she cruises at 33 mph and tops out well over 40 mph. She's proof that it's possible to get exciting performance in a sportboat without resorting to a gasoline engine. For in her engine compartment, where you'd normally find a five-liter V-8 taking up most of the space, there's a two-liter Yanmar four-cylinder diesel so narrow it looks lost. Two people could sit here, one on each side of the engine, and play cards on the valve cover. Obviously, service access is superb.
There are other striking differences, not the least of which is weight. Of course, everyone knows diesel boats are heavier that gasoline-powered ones, right? Not here. In fact, at 2,580 pounds, the Yanmar-powered version is 259 pounds lighter than its gasoline cousin. The V-8 weighs 938 pounds, compared to the Yanmar's 679 pounds, both with MerCruiser Alpha One stern drives. That translates into 4.26 pounds/hp for the gasoline engine versus 5.43 pounds/hp for the diesel. The V-8 produces 220 hp or 44 hp/liter; the diesel, 125 hp or 62.5 hp/liter, thanks to turbocharging and aftercooling.
Despite its modest size, however, the Yanmar isn't completely superior. A deficit of 95 hp takes a toll on performance. The V-8's top speed is 58.5 mph at 3950 rpm. However, fuel consumption favors the diesel. The V-8 burns 21.8 gph at WOT, delivering 2.7 mpg, while the diesel uses just 6.3 gph at WOT, generating 6.98 mpg. theoretically such outstanding fuel economy means the boat would have to carry less fuel-and therefore less weight- to achieve the same range, which might help narrow the difference in top speed. More important, at a typical cruising speed of 33 mph, the V-8, turning 3000 rpm, burns 9.9 gph and gets 3.4 mpg, while the Yanmar turns 3200 rpm, burns 3.2 gph, and generates 10.3 mpg. Put another way, the diesel Donzi can run at 33 mph for almost nine hours (294 miles) while the gasoline boat could manage only 2.9 hours and 96 miles. Since the diesel Donzi would make an ideal yacht tender, such range might be particularly useful if the yacht were in difficulty.
Among other benefits of the diesel-powered version, its reduced weight makes it less sensitive to outdrive trim and its sound level is lower, in large part due to the intake silencing provided by the turbocharger. The diesel Donzi is also somewhat quicker out of the hole due to the Yanmar's prodigious low-end torque. Against this is the increased cost of going diesel - a bit under $7,000 more than the V-8. Clearly, the cheaper cost of diesel and the Yanmar's superior fuel efficiency and resale could go a long way toward ameliorating that difference.
In the end, the choice of gasoline versus diesel power in a tender probably comes down as much to a particular owner's preference as practicality. But for a lot of yacht owners, the response to the pronouncement “out of gas” just might be, "Who cares?"
Donzi Marine (941) 727-0622. Fax :(941) 756-5638.
Yanmar (847) 541-1900. Fax :(847) 808-6968.
Chuck Husk is a former president of Chris-Craft. He holds a master's license.
DONZI CLASSIC 16 Specifications:
LOA: 16'6"
Beam: 6'11"
Draft: 1'0" (drive up); 1'11" (drive down)
Deadrise: 24 degrees
Fuel capacity: 30 gal.
Weight w/diesel (on certified scale): 2,580 lbs. w/ full fuel and gear
Engine: Yanmar 4JH3-DTE
Displacement: 121.7 cu in. (1995 cc)
Continuous output: 116hp (85.3 kW)
Maximum output: 125 hp (91.9 kW)
Specific fuel consumption: 6.34 gph @ 3700 rpm
Torque peak: 191.7 foot-pounds @ 3300 rpm
This boat is real, and so is her performance. In fact, she cruises at 33 mph and tops out well over 40 mph. She's proof that it's possible to get exciting performance in a sportboat without resorting to a gasoline engine. For in her engine compartment, where you'd normally find a five-liter V-8 taking up most of the space, there's a two-liter Yanmar four-cylinder diesel so narrow it looks lost. Two people could sit here, one on each side of the engine, and play cards on the valve cover. Obviously, service access is superb.
There are other striking differences, not the least of which is weight. Of course, everyone knows diesel boats are heavier that gasoline-powered ones, right? Not here. In fact, at 2,580 pounds, the Yanmar-powered version is 259 pounds lighter than its gasoline cousin. The V-8 weighs 938 pounds, compared to the Yanmar's 679 pounds, both with MerCruiser Alpha One stern drives. That translates into 4.26 pounds/hp for the gasoline engine versus 5.43 pounds/hp for the diesel. The V-8 produces 220 hp or 44 hp/liter; the diesel, 125 hp or 62.5 hp/liter, thanks to turbocharging and aftercooling.
Despite its modest size, however, the Yanmar isn't completely superior. A deficit of 95 hp takes a toll on performance. The V-8's top speed is 58.5 mph at 3950 rpm. However, fuel consumption favors the diesel. The V-8 burns 21.8 gph at WOT, delivering 2.7 mpg, while the diesel uses just 6.3 gph at WOT, generating 6.98 mpg. theoretically such outstanding fuel economy means the boat would have to carry less fuel-and therefore less weight- to achieve the same range, which might help narrow the difference in top speed. More important, at a typical cruising speed of 33 mph, the V-8, turning 3000 rpm, burns 9.9 gph and gets 3.4 mpg, while the Yanmar turns 3200 rpm, burns 3.2 gph, and generates 10.3 mpg. Put another way, the diesel Donzi can run at 33 mph for almost nine hours (294 miles) while the gasoline boat could manage only 2.9 hours and 96 miles. Since the diesel Donzi would make an ideal yacht tender, such range might be particularly useful if the yacht were in difficulty.
Among other benefits of the diesel-powered version, its reduced weight makes it less sensitive to outdrive trim and its sound level is lower, in large part due to the intake silencing provided by the turbocharger. The diesel Donzi is also somewhat quicker out of the hole due to the Yanmar's prodigious low-end torque. Against this is the increased cost of going diesel - a bit under $7,000 more than the V-8. Clearly, the cheaper cost of diesel and the Yanmar's superior fuel efficiency and resale could go a long way toward ameliorating that difference.
In the end, the choice of gasoline versus diesel power in a tender probably comes down as much to a particular owner's preference as practicality. But for a lot of yacht owners, the response to the pronouncement “out of gas” just might be, "Who cares?"
Donzi Marine (941) 727-0622. Fax :(941) 756-5638.
Yanmar (847) 541-1900. Fax :(847) 808-6968.
Chuck Husk is a former president of Chris-Craft. He holds a master's license.
DONZI CLASSIC 16 Specifications:
LOA: 16'6"
Beam: 6'11"
Draft: 1'0" (drive up); 1'11" (drive down)
Deadrise: 24 degrees
Fuel capacity: 30 gal.
Weight w/diesel (on certified scale): 2,580 lbs. w/ full fuel and gear
Engine: Yanmar 4JH3-DTE
Displacement: 121.7 cu in. (1995 cc)
Continuous output: 116hp (85.3 kW)
Maximum output: 125 hp (91.9 kW)
Specific fuel consumption: 6.34 gph @ 3700 rpm
Torque peak: 191.7 foot-pounds @ 3300 rpm