I live in Houston where a lot of the water is a mixture of salt and fresh - so callled "brackish water". Moomba recommends using their boats in "fresh water only". Does anyone know anything about using these boats in Salt or Brackish water?

I've heard of a device which can be attached to the engine and which allows fresh water (thru a garden hose) to be flushed thru the engine. Does anyone know how this works or where to buy such a device? My boat engine is the Endmar 310 HP.