How Much Fuel Does A Sailboat Consume?

Before setting off for your next sailing journey, you probably want to know how much fuel your boat actually burn. To give you a calculated answer, I have gone through some serious data analysis and wrote this helpful article for you.

So, How much fuel does a sailboat consume? On Average, a 20 – 30 Horsepower sailboat uses about 1.5 – 2.5 gallons of fuel per hour. Bigger engines (40 -50 Hp) uses about 2.5 – 3.5 gals/h.

These figures do not take the weather condition, the drag and size of the boat into account. However, they provide a close estimate that help us understand fuel consumption.

The estimate figures above are just examples of sailboats’ fuel consumption. There is actually a lot to calculating the exact usage which I will shed more light on in the sections to come.

How To Calculate Your Boat’s Fuel Consumption

Through my research, I have come across a few formulas on the boating magazine which allows us to calculate fuel consumption and it is a pretty close estimate. You can use the same formula to calculate both Diesel engine and Gasoline engine usage.

However, you will need to be sure to use the correct fuel consumption rate and fuel specific weight for your specific needs. I will give you these figures in this section.

The formula provides you with an estimate of maximum engine fuel you will be using on your journeys. It is calculated in fuel usage (gallon) per every hour. The actual formula looks like this:

Gallon per Hour = ( Specific Fuel Consumption rate x Horsepower) / Fuel Specific Weight

Here are the components of the above formula broken down to pieces:

Fuel Consumption rate:
A well-maintained four-stroke gasoline engine consumes about 0.5 pounds of fuel per hour per every unit of horsepower. Similarly, a well-looked after diesel engine consumes about 0.4 pounds of fuel per hour per unit of horsepower.

In short:
Diesel Engines Consumes 0.40 lb per Unit of Horsepower.
Gasoline Engines Consumes 0.50 lb per Unit of Horsepower.

Fuel Specific Weight:

These numbers are constants for any type of engine.
Diesel weighs = 7.2 lb/gal
Gasoline weighs = 6.1 lb/gal

To find out your engine’s fuel consumption, just plug in its horsepower figure and multiply it by fuel consumption rating, then divide the outcome by the diesel or Gas fuel specific weight constants.

This formula will give you an estimate and vary 10 to 20 percent, however, it will guide you to the right direction to plan a long distance sailing journey without fear of running out of gas.

Examples Of Sailboat Gas And Fuel Usage

Let us now bring some examples and apply the above formulas and constants to estimate maximum fuel consumption.

Example 1:

Maine Cat 38 has 19.8 Horsepower diesel engine. How much diesel does it consume per hour?

Gallon per Hour = ( Specific Fuel Consumption rate x Horsepower) / Fuel Specific Weight

We now know that The Specific Fuel Consumption Rate (SFCR) for this boat is 0.40 and the Fuel Specific Weight of diesel is 7.2 lb per gallon. Here is how we calculate the maximum consumption:

GPH = (0.40 x 19.8)/ 7.2 => 1.1 Gallon per hour.

Examples Of Sailboat Gas And Fuel Usage

Example 2

ClubSwan 50 has 75 hp gasoline engine. How much diesel does it consume per hour? 

Gallon per Hour = ( Specific Fuel Consumption rate x Horsepower) / Fuel Specific Weight

We now know that The Specific Fuel Consumption Rate (SFCR) for this boat is 0.50 and the  Fuel Specific Weight of gasoline is 6.1 lb per gallon. Here is how we calculate the maximum consumption:

GPH = (0.50 x 75)/ 6.1 => 6.14 Gallon per hour.

Examples Of Sailboat Gas And Fuel Usage

How Much Fuel Do You Need?

If you have a planning hull vessel, you will need more fuel than a displacement hull vessel. Let’s look at some examples of sailboats and their fuel usage.

Real life Example 1:

An 82-gallon tank of diesel powering a 20 hp engine, burning 1.10 gals/h will power the Maine Cat 38 for about 74.5 hours. If we assume that on average sailboats cruise anywhere between 6 – 8 nautical miles per hour. A full tank will give you approximately 450 – 600 nautical miles.

74.5 X 6 = 450

74.5 X 8 = 600

Real life Example 2:

A 27-gallon tank of diesel, powering a 30 hp engine, burning 1.7 gals/hr will power the J/121 for about 16 hours. This translates to around 100 -130 nautical miles of cruising distance.

Real life Example 3:

An 80-gallon tank of diesel, powering a 75 hp engine, burning 4.16 gal/hr will power the ClubSwan 50 for about 19.2 hours. This translates to around 120 -150 nautical miles of cruising distance for a full tank.

This calculation shows that it could get very expensive very quickly if you cruise under engine. However, most sailboat sailors can confirm that their boats sail a lot of time. I estimate that to be as high as 70-80 percent of the time.

Technically you only need the fuel for docking and getting in and out of the port. Once on the ocean, sailboats use little to no fuel. The boat is run primarily on wind power which is free of charge. Only on instances when there is no wind to push us forward that we use the motor to power the boat.

However, if you live or sail for a couple of days or more, you may need to run a generator to recharge your battery banks, cool the refrigerator, light the cabin, and use the laptops, etc.

From my research, I have found that on average, sailors run the generators between 3-6 hours each day when they are out on the ocean. So, this is an extra fuel consumption that you need to bear in mind.

For some sailors as soon as the boat’s speed drops to 4 knots, they reach the ignition key. As for me when I am out on the boat, I am in no hurry. I take my time and enjoy every moment that I am out there. Because it is the very place I want to be at the time.

11 Ways To Make Your Boat Fuel Efficient

Now that you know how to calculate the average fuel consumption on your vessel, you will probably want to know what are the ways to save fuel.

My research shows the amount of fuel you use on your sailboat is directly related to the way you handle the throttle and how much you load your vessel, but there are more.

I have found 11 contributing factors that affect your fuel consumption greatly while you are cruising, and we will discuss all of them one by one in this section.

By knowing and making these minor adjustments you will ensure you get much better fuel economy out of your sailboat.

1. Remove Excess Weight

Excess weight causes the engine to work harder to power your vessel, therefore, it will use more fuel. If you are sailing for a while you can easily confirm that boats collect stuff very quickly.

Unimportant items not only take up your storage space, but they also cause your vessel to consume more fuel. So, remove everything that is unnecessary and not used. Make sure that you are only carrying the cargo, supplies, and tools you are really in need of.

2. Use The Wind To Your Advantage

Just like sailing under the wind, use the wind in your favor. Avoid heading directly to the wind as this will force your engine to work much harder to push you ahead and therefore use more fuel. You need to find a balance and you don’t need to go overboard with this.

3. Avoid Carrying Excess Fuel And Water

Unless you have good reason to do so, it is not smart to sail with reserve fuel, excess water, and wastewater on board. These all add up to the weight of your vessel.

If you sail for a day or so there is no point running your boat with a full fuel tank. Fill up as much as you need plus a bit of reserve for the rainy day.

4. Tune up Your Engine

Your boat’s engine should ideally be serviced at least once or twice a year, depending on how much you use it. A tuned up engine will not only run better and it also uses less fuel.

If you haven’t used the engine for one year or more, give it a proper service to make it ready for the sailing season.

5. Pick A Good Prop Size

The right prop size is very important to attain fuel economy on your boat. It is worthwhile to beg or borrow a few props to try out on your boat and see which one gives you the best fuel economy.

6. Keep Your Hull Clean

A clean hull contributes significantly to the fuel economy. Make sure you keep the hull clean by washing it regularly.

7. Avoid Drag

Objects (hanging) on your boat may create excessive air drag and thereby increase your fuel consumption. To avoid drag remove objects that cause drag such as cockpit cover, canvas enclosed T-tops, hardtops, towers and things hanging on the lines of your boat.

8. Reduce Your Speed

Avoid cruising at maximum hull speed. Most motors are most efficient when they are run at about 75% of maximum hull speed.

Unless you intend to make it to a bridge opening or any other legitimate reason, slow down your boat’s speed. The lower your speed is, the less fuel your boat will consume.

9. Avoid Idling

Most of us are guilty of idling when we are on the water from time to time. However, you will be saving a lot on fuel if you just switch off the engine in most cases.

10. Balance The Load

Distribute the weight inside the boat to impove fuel economy.

11. Upgrade The Engine

If you have an older model engine, it is advisable to upgrade it now. As newer engines are designed to run efficiently.

Related Question:

How Much Does Your Fuel Weigh?

In order to calculate your overall weight, you might want to know how much your reserve fuel that your carry on board weigh.

So, How Much Does Your Fuel Weigh? Generally, gasoline weight about 6.1 pounds per gallon and diesel weighs about 7.2 pounds per gallon.

So, If you carry a 10-gallon reserve diesel can with you on the boat, it will make you 72 pounds heavier.

10 x 7.2 = 72 pounds


I am the owner of sailoradvice. I live in Birmingham, UK and love to sail with my wife and three boys throughout the year.

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