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May 04, 2007

Fuel-Efficient Fishing

Keep gas costs down, and keep your boat on the water

As I write, gasoline prices have jumped more than 30 cents a gallon in three weeks. Despite the news media's efforts to ferret answers from a reluctant oil industry, most of us consumers really don't understand these pricing dynamics. However, as boating anglers, we certainly understand how much more it costs to fill up our vessels' fuel tanks.

To better understand how our engines work and find ways to improve fuel efficiency while fishing, I talked with knowledgeable outboard techs and fishing captains who must constantly address bottom-line costs such as fuel. Their primary response: Get to know your boat and engine, and plan ahead to maximize your fun.

What's on Your Transom?
If your decade-old, carbureted two-stroke outboard coughs and wheezes, and you've considered re-powering in the past, make that re-powering choice now as a primary way to improve fuel efficiency. Today's outboards, both four-strokes and direct-injected two-strokes, use much less fuel and produce fewer emissions.

Long Island, New York, captain John Raguso (631-499-8140, has logged almost 30 years as a guide, running 13 outboard-powered boats. During his transition from 200 hp carbureted two-strokes to direct-injected two-strokes, then to his current 225 four-stroke Suzukis, Raguso kept records of his fuel burn at various rpm and speeds. Here is his performance comparison of the three types of engines. (While this isn't a scientific comparison of all brands of engines, it demonstrates one captain's real-life experience on the water.)

  • The carbureted 200s weighed 404 pounds each and featured 2.5-liter blocks. At 4,000 rpm, they produced 27 knots at 22 gph.
  • The direct-injected 200s weighed 507 pounds each and featured 3-liter blocks. At 4,000 rpm, they produced 29 knots at 18 gph.
  • The four-stroke 225s weigh 580 pounds each and feature 3.6-liter blocks. At 4,000 rpm, they produce 27 knots at 18 gph.

But the comparison doesn't end with just the numbers. When Raguso switched from carbureted two-strokes to DI two-strokes, his Phoenix went from serving as a marginal canyon vessel to a more reliable blue-water boat. A canyon trip that originally cost him 175 of his 200 gallons now consumed a mere 125 gallons. Because of the increased weight and displacement of the motor, he was also able to plane the boat on one engine.

When Raguso switched to four-strokes, he opted for the 225s to approximate the push at the prop of the 200 two-cycle engines. He theorizes that a four-stroke needs at least 25 hp and 300 rpm more to equal a two-stroke.

So, while transitioning from the DI two-stroke to the four-stroke initially required Raguso to rev his engines to 4,400 rpm to gain near 30 knots of speed, he found he could go up 1 1/2 inches in prop pitch because of the four-stroke gearing. With the increased pitch, he attained 27 knots at 4,000 rpm, burning the 18 gph reported.

In addition, while his DI two-strokes appeared to take the edge in fuel economy at speed, Raguso points out that they required oil, which, at an average of $20 a gallon, adds significantly to the overall fuel price. On the other hand, four-strokes do require periodic valve adjustment and change of oil.

Whether you choose two-strokes or four-strokes, improve your fuel efficiency by using a prop or props geared for the middle of your boat's rpm range rather than the top end, Raguso says. While that may create a little more load on the engine - one reason engine manufacturers often suggest propping for the top end - it will provide more headway at midrange cruising rpm.

What's at Your Console?
Regardless of your outboard choice, you can use your engine gauges - which now include vastly improved fuel-measuring systems - and your boat's electronics to improve fuel efficiency. But here's the rub: This takes time, patience and attention to detail - not strong suits for today's be-there-now American.

"SmartCraft gauges will give you exactly how much fuel you're burning at a given rpm for one or multiple engines," Litjens says. "It also gives you an mpg number. Our competitors also have fuel-management systems; that's almost a necessity these days. But you still have to have basic knowledge of what rpm gets you the best economy."

Between 3,500 and 4,500 rpm tends to be the best range for a boat on plane, he says. "The worst speed is when you're mushing - the bow is up and the boat is plowing with too much hull in the water. The motors are straining."

While on plane, changing engine trim can dramatically affect your engine's performance. While monitoring speed, rpm and fuel consumption on your gauge console, trim the engine up and down methodically and slowly to find an optimum height for the current conditions. Anglers often neglect to trim their engines high enough to find the upper rpm range.

Use the trim, throttle and tabs to select the most comfortable and efficient cruising speed for your vessel. Log your various speed/rpm combinations, and note the general attitude of the engine and tabs to locate your boat's sweet spot.

When rough conditions prevail, you'll need to use the trim and tabs to smooth out the ride; however, you can still use electronics such as chart plotters and autopilots so you won't sacrifice too much fuel economy.

"I use my plotter and autopilot to stay on a straight line," says Capt. George Mitchell, a south Florida guide who also fishes tournaments from his triple-Yamaha-F250-powered 33 Contender (305-257-4665, "When we ran from Destin [Florida] to the East Delta [Mississippi/Louisiana], I used my computer to chart our course and built myself the shortest route I could. I burned that onto a chip and uploaded it to my Furuno NavNet. Then I used my TR-1 autopilot. As good as I think I am, my autopilot is better. The quarter mile you save might make a difference."

When Mitchell fishes tournaments, plotting courses in advance - which includes stops at bait locations as well as fishing hot spots - becomes a fact of life. Not only is he trying to save fuel, he also has to maximize fishing time.

Mitchell also uses his radar to help him determine if boats may already be fishing his plotted locations. If he sees too many boats at a Gulf oil rig on his radar, for instance, he may pass by that location and run to the next.