I would think a good glass shop could make a hole just big enough to get all the wet foam out and fill the void back up. Then fix the hole the right way. It also looks like it's busted from the inside out, not like someone hit it. I'm not a professional though. It also looks like that is gel coat right on top of foam which is completely wrong. Should be a thin layer of fiberglass there

I really think some low life backed into you and drove off ..

It would be hard to miss that if you polished whole boat it would not of felt right.

The heat lights will draw the water out, that's why it will leak again.

It's just foam in the sponson correct?

I don't believe there is foam in a 1997 model. My 2000 does not appear to have foam anywhere, and I've been through it from bow to stern.

That wasn't patched and covered up. A patch job wouldn't just open up like that and they would've had to match the same gel coat and flakes which is extremely unlikely.

Looks like someone hit you. My cousins zx225 was hit in same spot with a prop at the dock and it looks identical to that

Priority one! Take it to a professional have him check it out, but not repair it until you know if it's new damage or old repair gone bad.
Then call insurance provider and cross your fingers.
If you in any way repair or try to repair it you won't be able to file an Insurance claim.
They will not pay for anything the can't see. with their on eyes.
Hope you come out ok!

The "rotten" smell is what would concern me most, cosmetic only damage is easily fixed and no big deal except for the hassle. Like someone else already posted I think those old Skeeter's have wooden transoms and stringers, and trapped water and wooden structural supports are a bad combination. You could use a borescope to investigate what's going on in there yourself but only a professional will be able to bore into the hull and determine exactly what's going on and still file a claim if its insured.

This pic looks like a repair job or its reflecting you taking the pic. My ex bother in law back into mine with a dually and only chipped the corner about the size of a dime and didn't bust through. Hit em wrong and they will crack. Hopefully they bent a prop shaft if some one did back into you and left with no note.....

I'm betting that someone did hit me if an old repair won't bust open because, I'm always back there pulling the plug and what not when loading and unloading and I'm very meticulous about my toys and would notice anything, we went out to eat last time after we fished, im thinking I may have been hit.

BTW, the back of your boat is the TRANSOM, not a "sponson".

Virtually all older boats have wood laminated into at least the transom. Decay of that wood would be a source of a foul odor. I'm not sure how fast this might happen after damage. An inspection by a pro repair shop can tell you more after inspection.

Now I'm confused. The part I have damage done to is what?
Is that considered the transom?

The sponsons are on the transom. The damage is on the sponson part of the transom.

That model Skeeter should have no wood.The C in Zx202C stands for composite.