Stretch Your Fishing Fuel Budget

When most boating anglers consider fuel economy, they think in terms of miles per gallon (mpg). Yet in this age of $4 or even $5 per gallon fuel, perhaps it’s better to extend that thinking to miles per dollar (mpd). When it comes to your fishing budget, that’s what really matters.

There are a number of ways to maximize this measure of fuel economy. Of course, new more-efficient hulls and marine engines can significantly improve mpd over older designs. But short of buying a new boat or motor, what can you do to boost mpd? Here are 10 tips:

If you have a trailer boat, avoid filling up at the gas dock. Fuel prices in the marina can be a $1 or more higher per gallon than at terrestrial pumps, whether you’re filling up with gasoline or diesel. If your boat averages 2 mpg at cruise, and filling-station fuel is $4 per gallon, you get 0.5 mpd (2 divided by 4). But if you fill up with $5 per gallon fuel at the gas dock, you’re getting only 0.4 — a 20 percent decrease in mpd (0.4 is 80 percent of 0.5).

This is one of the biggest steps you can take to increase your mpd if you're running a gasoline engine, according to David Meeler, Yamaha Outboards marine-product information manager. "For example, if your engine manual calls for 89 octane gas, don't buy 91 thinking it will run even better," Meeler says. "Greater octane costs more, but there's no performance gain. In fact, using too much octane can result in carbon buildup in the cylinders over time." Ultimately, keeping the price per gallon down helps increase the miles per dollar.

Few elements influence fuel economy more than the weight of your boat. The ­lighter the boat, the less fuel it demands to move it through the water. Yet boats experience a phenomenon called “load creep” as owners add more and more gear. To help offset load creep, periodically go through your boat to ­consider what you really need on board, with an eye toward shedding weight. Also, if you don’t need to keep your livewells full — like on the trip home — pull the drains to dump the water (which weighs about 8 pounds per gallon), and lighten the load to help boost mpd.

Adding something heavy like a hardtop, coffin box, generator or bait tank can affect your propeller needs. The prop(s) that pushed the boat just fine before the addition might now leave your engine struggling and burning more fuel than necessary, according to Yamaha's Meeler. To check, make sure the engine(s) revs up to the maximum-rated rpm range at wide-open throttle while underway. If not, step down to a lower pitch and retest. Also, think about a four-blade versus a three-blade prop, Meeler advises. Four-blades often create more lift and less wetted area under the hull. Though boat speed might drop, this also results in less drag and greater efficiency, translating to greater mpd.

Fouling such as algae and other marine growths generates substantial drag that can hurt your mpd. Anti-fouling bottom paint is the first step in controlling marine growth, if you keep your boat in the water. You should also have the bottom cleaned regularly by a dive service.

It's tough to gauge the most efficient cruising speed without a fuel-flow monitor. There are mechanical measuring devices from companies such as Flo-Scan and Lowrance, but ­e­­ngine-company digital instruments such as the Mercury SmartCraft or Yamaha Command Link Plus can also read fuel flow from the motor's electrical brain. "Using one of these lets you determine the 'sweet spot,'" says Meeler, "the rpm at which the engine is getting maximum fuel economy."

One thing a fuel-flow monitor might tell you is that you’re running too fast to achieve the best possible mpd. The most efficient cruising speed for many saltwater fishing boats is at the lowest possible speed at which the boat will stay comfortably on plane. After that, as speed increases, fuel economy usually decreases, although some stepped hulls such as the Contender 30ST or Invincible 33 can attain maximum fuel efficiency at higher speeds.

An engine that’s out of tune and running poorly also runs inefficiently. Have a qualified marine mechanic check out your engine(s) at least once a year, or whenever you sense you are not achieving maximum mpd.

According to Meeler, a dirty fuel filter can cost you mpd because the engine has to struggle to draw fuel through the clogged filter element. Meeler recommends changing the element in the primary fuel filter every 50 hours, or sooner if you notice a loss in performance. Outboard engines need at least a 10-micron filter element for the primary filter, he advises. A micron is one-millionth of a meter. To give you an idea of the size, the strand of spider web is about 2 to 3 microns in diameter.

Adjustable trim tabs, such as those from Bennett or Lenco, not only let you ­a­­djust your running attitude and level the boat side to side, but the lift they impart also lets you run on plane at a lower speed. For instance, if your fishing boat runs nicely on plane at 3,500 rpm without tabs, deploying the tabs ­slightly might allow you to reduce the rpm to 3,000 and still remain comfortably on plane.

Put these tips to use, and you might find you’re saving money on each fishing trip as a result of improved mpd.