Good fuel economy for a fishing boat

Good fuel economy for a fishing boat

Grady White 281 running shots
Efficiency at idle is very different from efficiency at cruise, which is again different from efficiency when the throttle is wide open.
Courtesy Grady White Boats

What is good fuel economy for a fishing boat? This is an inspiring question, because what constitutes “good” is open to debate. If you’re talking about a 65-foot-long, 100,000-pound sporting fish blasting across the ocean at 30 knots with 4,000 diesel horsepower moving through the engine room, a third of a mile to the gallon isn’t bad. At the opposite end of the spectrum, a jon boat with a 15-hp four-stroke outboard motor and a light load can get up to 10 mpg. Or you can go further and note that there are a lot of kayaks that qualify as fishing kayaks and get three or four miles per hour while only burning calories.

Comparison standards

When judging a boat’s fuel economy, the best way to do so is to compare boats of the same size. This is not easy. Boats are not standardized. For example, if two models have the same length, they may have different shafts and different horsepower with different brand engines. Then, there are environmental factors to consider. Has the boat’s fuel efficiency been measured in flat, calm waters, choppy seas, or in turbulence? How strong is the current, and was the boat moving with it, against it, or across it? The difference in fuel economy for the same boat can vary greatly from one day to the next.

Usage factors

350 HP Yamaha outboard motor
What is good fuel economy for a fishing boat? This is an inspiring question, because what constitutes “good” is open to debate.
Courtesy Yamaha

Now let’s talk about what all these boats do. Efficiency at idle is very different from efficiency at cruise, which is again different from efficiency when the throttle is wide open. Some boats provide great economy when going slow, but poor economy when going fast. Others are quite the opposite. So, where do you plan to compare it in the rpm range and speed range? This depends on how you use and operate your boat most of the time.

Given all these factors, it’s clear that we have to realize from the start that evaluating fuel efficiency on a boat is often an apples-to-oranges comparison with a few bananas and maybe a plum or two in the mix. However, we can look at a wide range of boats and make some basic assertions.

Category examples

Comparing five 18-foot center consoles with 115-hp outboards and running at about 30 mph is illuminating. At the top of the cruising efficiency range, one gets 5.7 mpg, and at the bottom, the other gets 4.2 mpg. The average for all of these rigs is 5.0 mph. However, does this gas hog get 0.8 mpg below average? Not necessarily, because it also has the most efficient slow speed, getting 8.8 mpg at around five mph while the other boats averaged 7.7 mpg. So, which of these boats has good fuel economy? Well, are you roaming or hunting?

Now let’s jump up the scale to a 25-footer running at 30 mph on a 300 hp outboard. The range narrows, with best economy recorded at 3.5 mpg and lowest at 3.0; The average sits at 3.2. Again, for whatever reason, the boat with the lowest mpg in cruising scores the highest efficiency at slow speed, but by a much smaller margin (4.6 mpg vs. average of 4.5).

Running with big dogs

Competitor boats
The larger the boat, the less difference you will notice in fuel economy between different platforms.
Competing boats courtesy

We go up again, this time onto 30-foot twin-engine platforms with pairs of 300-hp outboards. The spread shrinks further at 30 mph, from 1.5 to 1.8 mpg with an average of 1.7. When idling at trolling speed, fuel economy is no more than 0.3 miles per gallon. In wide open mode, they get no more than 0.2 miles per gallon.

So what can we say from these results? The larger the boat, the less difference you will notice in fuel economy between different platforms. If you’re shopping for an 18-footer, fuel economy deserves some consideration, but if you’re shopping for a 30-footer, less so.

Notable exceptions

However, there are exceptions. What happens when we introduce a multihull boat (aka Power Cat) to a 30-foot mix? The Cat takes the win on the top of the V body, with 1.9 mpg. How about adding a double-step hull to the mix? Best efficiency at 30 mph jumps to 2.1 mpg.

Of course, powerful cats and step structures have their own quirks and characteristics. Remember: apples, oranges, bananas and peaches. When it comes to fishing boats, it can be very difficult to define exactly what “good fuel economy” means. Which brings us back to those fishing boats. Because considering how bad boating’s fuel economy is in general, we don’t think you can beat five miles to get a turkey and cheese sandwich.

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