Sorry to hear all this,
but as mentioned by others, you need to act on this asap, like starting Monday morning! That marina is screwing around with you for sure!
A drop of water entering any of the firing chambers would likely cause a hydro-lock situation and stop the engine. You couldn't get the amount of water necessary to cause heavy rust of cylinders walls buy running the engine, it would have hydro-locked first.
Cranking a stubborn to start diesel (below water line types such as most sailboats) should only be done with the engine raw water in-let seacock closed, just don't forget to open the seacock once the engine fires off!