Need to understand cooling system

[dwleo]

OK.
I have a volvo-penta inline 6 cylinder with a screwed up exhaust manifold (leaky water jacket). A proper manifold will cost twice (at least) what the boat is worth. We got the boat as a 2 year 'work boat' to haul materials to a cabin we were going to start to build this year. The cabin is 10k from the marina. After it was done we were going to upgrade to a newer, nicer boat.

Now, how important is the cooling jacket around the exhaust? I realize it is there to cool the exhaust before it exits the engine but could one bypass the manifold and still keep the rest of the circulation? I am looking to find a way to keep the boat for the foreseeable future and maybe limit the speed.
What is the worst-case-scenario in this setup?
Thanks.

 

[JimS88]

Umm, I'm no expert but let's see, manifold gets so hot it lights your engine compartment on fire and you jump in the water, swim away and watch it burn. Worse than that you can't get off the boat or can't swim.

I know you don't want to spend anything on this project but you need to be realistic.

 

[el_pescador]

I couldn't have said it better. I know that some people have made their own custom exhaust manifolds in stainless steel and other materials, but I am not sure if you want to go there unless yo know what you are doing and can get the materials for cheap.