Re: What is my boat supposed to weight?
Whether or not you have a "problem" is going to depend on whether the wood in the transom and stringers is waterlogged. I'm not sure weighing is going to give you a true answer here; probably better to have that checked out if you think you do have a problem.
I can tell you this:
My last boat I weighed within a couple of weeks of purchase (brand new boat). It actually weighed about 400 lbs more than the manufacturer stated.
Boats tend to collect water over time and get heavier. Doesn't necessarily mean the boat is rotting from the inside out; gelcoat isn't waterproof and so water gets to (and in) the boat whether you want it to or not. So long as it doesn't get to the wood you're probably okay. The only real answer here is a tinny.
Whether both of these would add up to over 1,000 lbs, barring any water logged components, may not be outside the realm of possibility. I wouldn't panic just yet.