3 Cardinal Rules for Never Running out of Fuel

One of the more common boating emergencies is “out of gas” and small boat fuel gauges are notoriously inaccurate.

If everyone’s in the front of the boat the tank looks low but if they all move to the back you’ve plenty of gas.

What’s going on? Most small boats have a fuel sensor at the back of their tank which is a float on a rod connected to a coil that makes the fuel gauge needle move.

So – if the boat is bow-high, all the fuel runs to the back of the tank where the float is and the fuel gauge looks great. Once you’re up on a plane, the boat levels out, the fuel moves forward in the tank and the fuel gauge goes down.

Unfortunately the dip-tube that draws fuel for the engine is usually near the fuel gauge float so if the gauge shows low there’s probably not much fuel for the engine.

3 cardinal rules for never running out of fuel

1)Fuel flow monitor

fuel flow monitor

The best answer is a fuel flow monitor which keeps track of the amount of fuel you’ve actually burned. Many modern engines have this feature but if yours’ doesn’t here’s a simple, cheap solution.



2) So always leave with a full tank!

tank gauge

First, use the 1/3 rule. One third of your fuel going out, 1/3 coming home and 1/3 for what you didn’t expect.


3) Know your fuel consumption rate!


For example, if your tank holds 60 gallons and you burn 10 gallons/hr at full throttle you have 6 hours total to run around – 2 hours out, 2 hours back home and 2 hours to spare.

The fuel consumption rates for many engine/boat combinations are available online.

If you can’t find your specific case, you can use the following rule-of-thumb: Modern 4-stroke marine gasoline engines in good condition will burn about 0.4 – 0.45 pounds per hour per horsepower at full throttle (0.6 to 0.8 for 2-stroke engines).

This means that if you have a 100 horsepower 4-stroke engine it should burn about 40 to 45 pounds of fuel per hour which at 6 pounds per gallon is about 7 gallons per hour at full throttle. To convert this into liters you can multiply 7 gallons by 3.8 (3.8 liters per gallon).

Once you have your fuel calculations meticulously computed to the nth decimal point and you feel you are ready to embark, hold on to your horses! Or horsepower for that matter. TIMEZERO software now has a function inside the Advanced Route Planning software called the route wizard. While it may be called a wizard, it is actually just advanced algorithms that work out the best time to leave for a voyage. In short, the same engine/boat will not use the same amount of fuel depending on your average speed, the time of departure and currents.

This great yet simple tool is available in the entry-level marine navigation software TZ Navigator v3: The Advanced Route Planning. After creating your route on the marine chart, this assistant appears automatically to recommend the best departure time depending on the criteria you choose.

Sailors can save hours of navigation on a route in critical areas like the Channel. A purchase that pays itself back!

Find out more about this tool and all TZ Navigator v3 features here.


Product Page TIMEZERO