I keep me boat in a dry slip and the marina workers put my boat in with a forklift when I need it. Well They put it in without my plug and the boat filled with salt water for about 30 min. The water submerged the lower half of my engine including the starter and alternator. At the time my battery was disconnected. They pulled the boat back out of the water, drained it and started the engine. It ran okay at this time. We then used the boat for about two hours and it ran okay. I have a 1971 I/O Chevy 4 cyl. engine with Mercruiser (they tell me it is the same engine previously used in the Chevette cars). It appears that no water got into the oil. What parts should I have replaced and should I be concerned about the corrosion from the saltwater over time.