Could be hatches and windows. The foam gaskets go hard and start to leak. The solution is to remove them all, clean off all the old foam gasket, and re-bed them using Abromast butyl sealant.
Could also be stantion bases, especially if the boats had a ding (creeping crack sealer is good for this).
Could also be the toerail or hull-deck joint.
Unfortunately it can be difficult to get to the bottom of this problem, it took me a while (I also have a 2003 boat, and could get a bucket-full out of the bilge in a day). I would suggest that you do the hatches and windows first, and see if that sorts it. If not, then start looking at other stuff.
Hope that helps
Bob
PS. Mine was the hatches and windows, which is why I suggest you start there.
