Ask SAIL: Leftover Gas in Tank


Q I have two 6-gallon gas tanks on my 25-foot O’Day, but when the motor quits and I have to switch tanks, there is still about 1 1/2 gallons left in the “empty” tank. What is causing this, and what can be done about it? Could it be the setting of the air intake?

Nigel Calder Responds

My guess would be the suction lines are set an inch or so off the bottom of the tanks to avoid drawing in any water or sediment that might collect there. This is a common practice with marine fuel tanks. Typically, the tank is much larger, so leaving 1 1/2 gallons on the bottom has little impact on overall fuel availability. However, with your small tanks it is obviously a significant percentage of the available fuel.


Nigel Calder is an author and expert on boat systems and diesel engines



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One comment on “Ask SAIL: Leftover Gas in Tank

  1. Mauricio Laynes

    Mr Nigel, sorry about my english, I´ll try to explain my doubt. My 36 ft sail boat "Shanti" is equipped with: 03 85Watts solar panels with a 20A Sunsaver controller,  Diode Isolator Argos 12002SC  and 02 12V battery banks. Could you explain how the banks are charged in many situations such: Using shore power and solar panel, using motor with shore power and solar panel, using mnotor with solar panels?

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