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Usable gas

Old 08-13-2019, 06:09 PM
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Default Usable gas

Saw a post in the for sale forum , 340 single gas tank with 300 useable gallons. Seems like a lot of unused gas sloshing around the bottom of the tank. Is there any formula to deterime this ? I understand that fuel pick up and placement of it may vary to alter the useable fuel. Just thinking you should be more in the 320 gallon range of burnable fuel.
Old 08-13-2019, 06:30 PM
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Too many variables. No formulas that I know of. Testing is the only way to be sure.

One tank may allow damn near all of the gasoline to be consumed and burned. A different model may have a high quantity of unusable gasoline.

Then too, it matters if the unusable quantity is based on the boat being at rest or the boat being on plane. A long narrow V bottom tank with a pick up probe at the rear, say a quarter of an inch from the tank bottom, may pick up damn near all of the gasoline when the boat is on plane. Tank elevated in the front. Gasoline flows to the rear. Same tank with the boat at rest may not draw as much usable gasoline.
Old 08-13-2019, 07:05 PM
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Losing 40 of 340 is a little high. I have 100-250-100, and sputtered to the fuel dock once after burning (if I remember right) 426. Not apples to apples but that seems high. That’s losing 11.8%, whereas I lost 5.3%. Like the above said, you pretty much have to do it to know.
Old 08-13-2019, 07:09 PM
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My Onslow has a 350 gal tank and usable is 330. It takes an extra 20 minutes to pump in the last 20 gallons.
Old 08-13-2019, 07:27 PM
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My 251XS Has an "80 gallon" tank. It's done at 56 gallons. I'm not real happy about that...
Old 08-14-2019, 03:57 AM
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The new EPA compliant tanks on new boat lose about 20%. The boat I'm building has a 400g tank with 375g nominal and 364 usable as specified by the manufacturer.
Old 08-14-2019, 04:09 AM
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Imagine rectangular tank, 12" high, with pickup 1/2" off bottom. Thats 4.2% . Anything more seems poor. Tank n/boat not run level with pickup near front....you likely double it +. Boats like to run bow high. Pickup should be at rear of tank.....obviously.

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