Can anyone tell me how to convert a freshwater boat to a saltwater boat? Or does it really matter?

Can anyone tell me how to convert a freshwater boat to a saltwater boat? Or does it really matter?
There is no conversion, only the type of water you put your boat into changes.
What you do to your boat once out of the water changes quite a bit: You need to thoroughly flush the engine's cooling system to make certain the salt residue is cleaned out so the internal components don't corrode. Extra care needs to be given to the entire boat, for that matter, including keeping the electronic stuff clean and free from corrosion.

Hey Capt, missed you my friend, how have you been?

Stringer

THERE IS a CONVERSION that can be done. It's called a closed cooling system. (not for an outboard but for an I/O.) Basically the engine water jacket (block)is filled with antifreeze and raw water is drawn up from the ocean through a pump to a heat exchanger to cool off the antifreeze). The block itself though is never exposed to salt water but the risers and exhaust system still gets exposed.