unplug the bilge pump and fill the bilge with water. See if water comes out of that joint or any of the damaged areas. Or go opposite and put it in water and see if bilge fills up with water - this will be a little harder to identify where it's coming from.
The dents may cause it to ride or drive funky, or cause spray to come in the boat under certain or all conditions.
As a general matter, who cares if your dentable boat has dents in it. This falls under the one rule I have for boats now: "pay for a boat what you don't mind dropping to the bottom of the lake." They're money pits. If you're driving around on it to pick up chicks, or so your kids can brag at school - I have no advice. If you're using it to make groceries, it's a tool.
The only way to know if the dents matter is to test it. Or take it to a boat builder/repair shop you trust. If you're asking us, you don't have one.
Pretty simple though - if the dents didn't make cracks that leak, and they don't cause the boat to be out of control under the conditions you'll use it, and it doesn't cause the boat to spray you constantly, they're just dents.
Take it to a boat repair shop and get a quote. Tell the person selling it "the shop says it's x.xx dollars to fix that. what are your thoughts?" Then shut up and let them talk.
