Ok, so I took the boat out today and it had about 3/8 of a tank in it according to my gauge, but when I looked at the tank it looked over half way full.  It was old gas (3 months) so I wanted to burn as much as I could out of it so I didn't put any gas in it.  Well I drove about 30 miles on the Potomac today and when it hit about an 1/8th of a tank (gauge reading), my gauge dropped like a rock.  I was a little worried, but not too much, that I wasn't going to make it back to the dock.  I looked at the tank when I got back and it still looked about half way full.

 

My question is, do the gas tanks have thick solid bottoms for supporting the gas weight?  My gas tank is segmented (hard to explain) but the bottom part looks like it has gas in it, but I think this just may be solid plastic or filled with something other than gas.  I'm wondering if this makes the tank look more full than it really is.  

 

I'll be able to tell the next time I fill it up to see how much gas it takes, but I don't want to do that until the season starts so I can have fresh gas (please no ethanol treatment comments).  I guess either my gas gauge is way off or the bottom 1/8-1/4 of the tank is filled with something.  

 

Any thoughts?

I don't know about your tank and how it is made, but mine is not visible and my gauge is terrible.  My boat holds 55 gallons of gasoline and shows full when I top it off.  After about 5 gallons are burned it shows about half a tank.  It will stay that way for a long them then drop to 1/4.  That is when I get antsy and fill it up.  The gauge has never worked correctly and I have had this boat a long time.

I don't know about your tank and how it is made, but mine is not visible and my gauge is terrible.  My boat holds 55 gallons of gasoline and shows full when I top it off.  After about 5 gallons are burned it shows about half a tank.  It will stay that way for a long them then drop to 1/4.  That is when I get antsy and fill it up.  The gauge has never worked correctly and I have had this boat a long time.

Thanks.. my buddy said the same thing with his.  It just hit 'E', so I guess I'll just go fill it up next time and see how many gallons it takes.  That should tell me if my gauge is screwy.  Still curious about what the bottom of the tanks are made of. 

I run my boat on E for quite a long time. I'm not convinced that gas gauges on boats are accurate. I can look at my tank and see that it's 1/4 of the way full when the gauge is riding past E. . . 

Ditto to Jig Man. I have 2 - 22.5 gallon tanks. When the gauge for each is on empty they are really half full.

Ditto to Jig Man. I have 2 - 22.5 gallon tanks. When the gauge for each is on empty they are really half full.

Alright thanks guys... it sounds like this may be the case for me as well, but I'll fill it up before the next time I go out to see how much it takes and I'll be able to verify.  I've never had it this low before so I never questioned my gauge.  

My gas gauge is crazy like that too. Its never really accurate.

My 2 26 gallon tanks take 10 gallons each to move the gauge.