fuel tank dilemma

[TarponTom]

I have only had my 23 Sceptre for a few months and until recently only went out on day trips and topped off the tank before the next trip. Last week I took the first vacation with the boat. Again I topped off the tank so it was full when I started the trip. On the last day (luckily) a few hundred yards from the dock I ran out of gas. I shifted people and gear to the stern (pick-up is in the back) and managed to crank the motor and get back to the dock! Now hears the wierd part. On the way home I stopped to fill-up expecting to need a bank loan and it only took 70 gallons! I tried but could'nt get another drop in. I am going to check the pick-up to see if for some reason its cut short but other than that, I'm lost. Any similar experiences?
Every thing I have read states it should have a 144 gallon tank.