How to Find Out Your Boat Gas Tank Size

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Updated on April 2, 2022

Locating your boat’s tank size should be among the first things you do after its delivered to you. The gas tank size of your boat determines its range when you turn on its engine. 

You can locate a boat gas tank size by checking its service manual, checking its pasted placard or by gauging. It’s also possible to find the boat gas tank size by taking measurements and making some conversions. 

In this article, you’ll find every relevant detail required to find your boat’s gas tank size.  

How Much Gas Can a Boat Hold?

A small boat could hold around 5 – 40+ gallons of gas in its tank (based on its capacity). Some big boats and luxury yachts can hold as much as 250,000 gallons in their tank. 

However, it is easy for boaters to customize their boat tank size to best suit their needs. Since boats don’t have strong fuel efficiency, many boaters prefer to increase the size of their fuel tank if needed. 

How to Know the Size of Your Boat Gas Tank

First way to know the size of your boat gas tank: Check the owner’s manual of your boat

Step 1: Open Contents page of your boat’s service manual

The Contents page of your boat’s service manual shows information required to locate relevant details.  

Step 2: Check for fuel/fuel efficiency

Check for the ‘Fuel’ or ‘Fuel efficiency’ pages in the service manual (from the Contents page). 

At this section, you’ll get information to spot the exact gas capacity of your boat.  

Second way to know the size of your boat gas tank: Fill up the tank after it gets empty

Step 1: Use the boat to its minimal gas level 

Run your boat’s engine until its fuel gauge is at its lowest level. Don’t use up the gas in your boat when you’re too far off at sea to avoid getting stranded. 

If you don’t want to use up gas in your boat’s tank, draining out fuel could be a safer option. 

Step 2: Add gas from a measured container

Get gas in a container with accurate measurements (in gallons). Fill up the gas tank until it gets to the highest point of its filter. 

Step 3: Check container for remaining fuel after filling

Take note of the volume of gas your boat’s tank can contain. You’ll be able to determine the gas capacity of your boat.  

Third way to know the size of your boat gas tank: Taking dimensions of the tank

Step 1: Get a measuring rule/tape and take tank dimensions

A measuring tape with measures in feet, inches, or meters will work to get the dimensions of your boat’s tank. Next, measure the tank’s length, width, and height.

Step 2: Convert into cubic feet, inches, or meters

Multiply the length, width, and height of your tank to get its measurement in cubic feet, inches, or meters. Note that your first reading determines whether you’ll get the tank measurements in cubic feet, inches, or meters. 

Step 3: Convert into gallons

Convert your measurement from cubic feet, inches, or meters into gallons. 

There is approximately 7.48 cubic feet in each gallon. If your measurement is in cubic feet, multiply it by 7.48 to get your boat tank volume in gallons. 

There’s 0.0043 cubic inch in a gallon. You need to multiply your tank measurement in cubic inches by 0.0043 to get its volume in gallons. 

You’ll also need to multiply your tank dimensions by 264.17 to get its estimated volume in gallons. 

Fourth way to know the size of your boat gas tank: Checking the pasted placard on your boat’s tank

Step 1: Inspect your boat’s tank

Most boat models have a metal plate or sticker with basic information about its performance, mileage, and gas capacity. 

Step 2: Check for its gallon size

Find the information about your boat’s gas capacity from the attached placard. Most times, this information should be available in liters or gallons. 

How to Find Out the Gas Range of a Boat

The gas range of a boat is its one-way distance on a single, full tank of fuel.

Step 1: Get relevant parameters

Three parameters must be found before getting the gas range of any boat. You need to find the gallons per hour rating, nautical miles per gallon and gas tank capacity. 

A gallon per hour is equal to your boat’s horsepower divided by 10. You can get the nautical miles per gallon when you divide the boat speed by gallons per hour.

Step 2: Calculate the range

Next, you need to multiply nautical miles per gallon by the boat tank capacity. Then, multiply your result by 0.9 (safety margin estimating usable gas in your boat’s fuel tank)

How Far Can a Boat Go on a Tank of Gas?

A boat can go over 5 miles on average on a single tank of gas. Other factors like the tank size, speed traveled, and more can determine how far a boat can go on one tank of gas.