100 gal tank, usable fuel?

[DSW]

Hi,
In a 100 gallon tank what should I expect as the usable fuel? I have a '97 2110 and I know there are a not a lot of that model, but I expect other 21' like the 2120 should be similar. What % do you need to say is unusable?

 

[TomS]

I can't give you an exact answer, as it will also depend on your pickup tube setup, but I can tell you the most I have ever added mid-season was 88 gallons. No way to tell how much more/longer I could have gone, but I didn't really want to find out

-- Tom

 

[Brent]

If you replace the fuel pickup tubes, measure tank depth and cut as long as possible


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[DSW]

Thanks for the input, I'll see what I can figure out.

 

[tjd24]

I've read that you should assume that 10-12% of total gallons of fuel are unusable.
I use the 10% figure for my 2320SL. So, of the 137 gallons in my tank, I count on 124 usable gallons.

 

[Brent]

Replacing the fuel pickup tubes is easy. 1/2 inch off the tank bottom and have Racor water and fuel with clear bowl installed

 

[Ludicrous40]

If you're using your boat on the ocean, 10% remaining is dangerously low, and you should be more conservative. My tank is 173 gallons, and on one trip it got really rough on the way in, and I thought I was good. Engine quit, fuel bulb collapsed on itself due to sucking air. While bouncing around, managed to get it re-primed, limped in slowly, and surprisingly made it. Refueled the boat, and it took 163 gallons, so I figure when I ran out, I was around 20 gallons remaining. I determined that my fuel remaining information was unknowingly off as I thought I had closer to 35 gallons , but I'll never let it get that close again.

 

[GoodChance]

I guy who built my tank (different boat) said that in most tanks, 93% of the total volume is usable. I've never tested that limit but felt it was a good rule.

 

[PastTheBarb]

Ive owned my 97 21 DV for three years now. Ive only let it get below half a tank once. Im nervous that the gauge is like the one in my car.
My diesel Jetta can go 600 miles on a tank but when the gauge reads 1/2 Ive traveled 400 miles. The next 200 miles the gauge sinks pretty fast. This is true of every car and truck Ive owned. My question is, is that also true of my boat. I dont want to find out the hard way.