Why is this plumbed this way?
 

I am working on getting this Superboat going. I have a really bad boat problem. When I bought the boat I new the engine had taken in water and needed to be replaced/rebuilt. The owner said the boat overheated and cut out. His mechanic said the engine overheated and caused the exhaust manifolds leaked water in. I am in the process of removing the engine now.
I have never seen water routed this way? I have always plumbed incoming water to a crossover in the block then the water circulates through the block to water outlet/thermostat housing and then to exhaust manifolds. As you can see in the photo incoming raw water goes to a "T" in the block which then goes to the water outlet? To me this wouldn't pass water through the block necessarily? All may be diverted to exhaust manifolds?
https://cimg8.ibsrv.net/gimg/www.off...898d74d59.jpeg

Plumb it the way you think it should be done. That mess is much more complicated than it needs to be.

Thats my opinion.

Whatever that puzzle is it appearantly didn`t work so well . I agree with Tom , rip it all out and start fresh

Thanks guys not sure what was going on there. I will redo the tried and true way.

https://cimg6.ibsrv.net/gimg/www.off...0f491165cc.jpg
I guess the water system did work. The cylinders got a lot of water.

I didn't know marine engines were using water injection now too!

Ouch!

Gaskets installed upside down or wrong gasket?

I don’t know that it was the head gasket? Do you see something?
On the forensic examination the raw water pump plastic body had a section missing so I think it overheated. Both banks had the same water in them so I don’t think it was an exhaust manifold because I don’t think 2 would fail at one time. I think water got sucked back into the engine from the exhaust. Flappers not working.

ouch... serious mess here !
needs serious doctor to fix this ...