Why Do Boats Burn So Much Gas? (Explained for Beginners)

Have you ever wondered why your boat consumes more fuel than your car for the same distance?

Why do boats burn so much gas?

The main reason why boats will always burn more gas than cars is they run on water. Aerodynamics, wind resistance, waves, and drag affect the fuel consumption of a boat. Basically, a boat needs to use more fuel to cover the same distance a car will cover.

Why Do Boats Burn More Gas Than Cars?

Boats are one of the least fuel-efficient vessels on the planet.

Boats will measure their fuel consumption in gallons per hour (GPH), while cars use miles per gallon (MPH).

This means that boating manufacturers use different tactics when making their products as fuel-efficient as possible, usually over a distance, rather than with speed.

Because of this, you are less likely going to save on fuel-efficiency with a boat than you are with a car.

Let us look at some commonly asked questions before we look at these fuel-saving tips:

How Much Gas Do Boats Actually Burn?

Many small, private boats will use about 3-8 gallons of gas per hour at cruising speeds. Faster watercraft at breakneck speeds can use 20-30 gallons in one trip.

Depending on your boat’s weight, size, and style, you can consume or save much more fuel.

A poorly maintained engine also will burn more fuel than one that is properly maintained.

In areas such as the hull or transom, a boat in overall bad maintenance will also contribute to poor gas mileage.

You can check out our article on How Much Gas Do Boats Use? 5 Boat Types Explained for more information on the amount of fuel that boats burn.

Why Do Boats Burn Much More Gas Than Cars?

The simple answer is cars run on solid ground with less resistance, while boats run on water, which has more resistance than wheels on solid ground.

If you take something like marble and roll it along with a table, you will use minimal effort.

However, if you move the same marble across a water container, you will need more effort to maintain the same speed.

Water-resistance is a huge factor in fuel consumption – the harder your engine is working on getting your boat across choppy waves, the more fuel you will be burning in the long run.

How Do You Save On Gas For Your Boat?

Saving money on gas for your boat comes down to how you operate your boat, the kind of gas you are using, and the engine you bought to go with your boat.

Here are a few main points to remember as you go:

1. If you are using a smaller engine and working too hard for your big boat, you will lose a lot of money on gas.
2. If you are using the wrong gas for your type of engine, you will end up burning way more of it as you go.
3. A need for speed will kill your fuel reserves way faster than you anticipate. Slow down!

We list nine ways to keep your boat more fuel-efficient here! Check it out!

9 Ways To Make A Boat More Fuel-Efficient:

Speed should not be the biggest factor in buying a boat for someone on a budget.

Rather, they should be focusing on saving themselves money and fuel every time they go out on the water.

The following are nine guaranteed ways to improve your boat fuel consumption:

1. Minimize Miles Travelled

If you try to sail or motor from one point to the other, try to take the shortest route.

Usually, on a body of water, that means going in a straight line. This will save you time and fuel in the long run as you navigate your way as fast as possible from point A to point B.

If you take a lot of detours, you may run out of fuel faster than you thought.

2. Make Sure Your Engine Size is Right

Having the wrong engine size is the surefire way to mismanage your fuel and your speed.

If your boat is large, getting a smaller engine than it needs only makes it that much harder to save on fuel and get you where you need to go.

Make sure you are using the right engine provided or recommended by the manufacturer, and try not to overwork a smaller engine.

3. Pack Light

Another fuel-saving tip is trimming the fat. What can you leave at home, and what do you need to carry?

Packing light can help you solve this problem!

The less weight that an engine has to resist when on the water, the easier it will be to get up to speed and keep your fuel consumption light.

If you can leave it at home, do so!

4. Don’t Go So Fast

Everyone wants to travel fast on their boat, but this can usually cause you problems and cost you a lot of fuel in the long run.  Not only is it going faster, much harder on your engine, but it will burn a lot of gas over a shorter period of time.

The most efficient running speed averages 25 mph in most powerboats, but it really depends on the boat’s design.  The average speed of 25 mph is good for a boat that planes on the surface of the water.  But a displacement hull (like on a trawler yacht) will not plane, and the faster you go, the more resistance it has and the lower the efficiency.

This means that your boat will either run out of fuel faster than you anticipated, or the strain on the engine will potentially shorten its lifespan, and you’ll have to get a new one.

If you can slow down, try to. It may help you later.

5. Work With Your Engine’s Needs

The most efficient running speed is usually called the cruising speed.  On a planing hull, the boat is up on the water surface, and the engine can still go faster, but not as efficiently.  On a displacement hull, at cruising speed, the boat is moving through the water with a good balance of water resistance and speed, so the engine is not over-working.

Gasoline outboards find their sweet spot between 3000 – 4000 rpm, while diesel engines find it somewhere beyond 2000 rpm.

If you know what your engine needs, make sure that you are operating at that speed. It will help keep your fuel more efficient in the long run!

6. Choose The Correct Propeller

The propeller is an essential component for running a boat at topmost efficiency despite the engine you choose.

Boats should be propped to work in the required top rpm band with a full load of people, fuel, and gear. The wrong prop may cause your engine to dog it a bit, over-revving or under-revving.

It all depends if it is over or under-propped. You may need a professional to assess the propeller performance to make sure it is the best it can be.

7. Clean your Boat’s Hull

Engine operation aside, one of the best ways to boost efficiency is to run with a clean bottom.

Algae and barnacle growth can aggravate drag, depriving you of miles per gallon. Running a bare fiberglass hull is the best thing to do to save fuel.

Applying wax may make the bottom smooth, but it holds air bubbles near the hull, which causes more friction than you’d expect.

8. Update your Fuel Gauge

Most fuel gauges on boats are a little difficult to trust.  If it is working accurately, you can monitor your boat’s fuel use more accurately.

Often, especially on old boats, fuel gauges can be inaccurate or outdated.

If your fuel gauge is not working properly, or you think you have less or more fuel than it is telling you, update your gauge and get it checked by a professional.

9. Fuel Additives

You may try to avoid it, but it may be impossible to find gasoline that does not have some form of ethanol content.

Apart from being a potential hazard to your engine, ethanol harms fuel efficiency.

There are fuel additives available you can use to ensure the gasoline in your boat burns more cleanly and efficiently.

Final Thoughts

Increasing fuel efficiency on your boat should not be a daunting task.

With the right knowledge of your boat and its needs, you can save a lot of time, effort, and money on getting fuel for your boat.

When in doubt, remember that a boat is supposed to burn more gas than a car, so try to bring extra and don’t go too fast!

References:

https://www.passagemaker.com/technical/feel-the-burn

https://www.bellperformance.com/blog/tips-for-increasing-the-fuel-efficiency-of-your-boat

https://www.beautifullife.info/automotive-design/fastest-speed-boats-in-the-world/