Well, on my '96 Glastron 1/4 Tank = Empty...but the thing would read 'Full' forever...once the needle started to drop we had to get gas.
Might not even need to replace it Josh, its just learning the personality of the boat if the gauge works.
Mine doesn't work at all either...every time I think to replace it, the gas tank is full to the brim, so I can't open the tank to replace the sender.