SAN overheating

Today we were out and the engine hot light kept flashing and my temp was up at 200. I installed a flush kit last year so I could see that the water was not being pumped through to the engine. Am I looking at just an impeller? or water pump?? and would I have damanged the engine any by idling back to the dock?

at 200 you will probably have been ok. Check the impeller first and replace that and if there are chunks off of it, backfluch the engine to clear it out. At that temp, feel the exhaust manifold hoses to see if they are soft and collapsed, and if so replace them too.

check impeller - damaged or seaweed/gunk in there

check the fresh water strainer thing, if that gets an air-leak it wont prime/flow unless you're going fast enough to push water through

Usually you don't have seaweed in the impeller housing. It almost always started in the raw water strainer. Like Nick said, either air leak or if it's completely clogged with silt, sand, seaweed, the impeller will run dry and start to disintegrate. No water and impeller will be toast in well under a minute.