exhaust manifold gasket replacement question

[newbie Mike]

I have a ford 460 and one of the exhause manifold gaskets has a chunk missing, number 7 cylinder. When I ran the engine is when I noted it. I want to take the boat out for the July weekend coming up. The headers are through transom exhaust with snails water cooled. The engine is not covered, so my question is what are the downfalls if I do not replace the exhaust gasket? I would appreciate any comments as I value the experience on this forum.
Mike

[Oldsquirt]

You should replace the gasket. It shouldn't take more than an hour.

[Ken F]

If you take out all the bolts except the two on each end, you may not even have to pull the manifold off the boat. Buy your gaskets first, and look at them. you will see why. May be able to clean things up well enough without pulling everything apart, but as O.Rigger said...you need to replace it.
Ken F