Motor mount leak

I have a 1985 Sunsport that I bought from the original owner. The boat really is in great shape but i am fairly certain there is some stringer rot due to issues with the motor mount lag bolts spinning out.

This off season I was chasing an unknown leak due to some water getting in the bilge. I filled it up with water and had water coming up around the rudder plate. I pulled that up cleaned everything up and resealed it.

After getting it on the water we noticed water coming in around the rear driver side motor mount and bolts and water pooling at the point where the exhaust goes through the floor in that area. I think it is rather a leak around the exhaust where the flappers.

What else may cause water to be coming in that area?

May be the sealant around the exhaust pipe where it goes through the transom.

That is what I am thinking/hoping. The seal around the pipe flange appears to be intact but I have seen people mention that there is a secondary seal 4 inches in from that exhaust penetration that can be a failure point so worth going over all of it to eliminate that as an issue.

I thought I might have been getting water through my rudder port because it does have excessive play indicating it may need a tune up but wouldn't a failure in the rudder port seal just have water coming into the bilge and not in-between the two layers of the boat?

So I got the boat out of the water and took the back seat and gas tank out to get a better look at things.

The area where the driver side exhaust comes through the transom had a good bit of water. The exterior seal looked good but on the interior seal they used that red gasket maker stuff. Which I'm not sure is good for a below waterline marine application. There was also a few small drips from the swim platform bracket on that side but it was so minor I would be shocked if that's all it was. But it will get sealed up with everything else with 3m marine.

While I have it apart I'll probably try and rebuild the rudder and reinforce the swim platform. The foam was in good shape and the stringers in the area are still solid. I think I'm going to fabricate some sort of metal angle piece to mount to the stringers and then bolt the engine mount to that pieace since my engine mount bolts are hit or miss.

Just to close this up in case someone has this issue. I tore the back of the boat up and resealed the exhaust and everything I could see that could be a leak point. Put back in the water and still had water coming up. We left the plug in and pulled the boat out and all the water came out of a small hole about the size of an eraser.

I was shocked how quickly a small hole could let water in. But we sprayed stop gap foam through the hold to plug the foam up and filled the hole with JB weld.