gas tank and computer question

[menuserve.com]

so I used 13 gallons of gas according to the computer, but the needle is on half a tank.

is the reserve really 6 gallons or whats going on?

[MarineHawk]

http://www.elcovaforums.com/forums/showthread.php?t=8018&highlight=fuel+gage

[MovinH2]

so I used 13 gallons of gas according to the computer, but the needle is on half a tank.

is the reserve really 6 gallons or whats going on?

A couple of times to me. :(