You can find any major leaks by lightly pressurizing the hull with a compressor (5 lbs or so).
Using an air compressor is a good way to blow up your hull. I've seen the results, and there's no fixing it once it's blown.
Use a shop vac set on "blow". Do not connect the hose directly to the drain plug hole.
Lightly pressurize the hull - it's way less than 5 psi. You want to blow bubbles, not blow up the hull.
