Ah, the joys of boating! In a lot of ways, it doesn’t matter if you’re on freshwater or saltwater, just as long as you’re on the water. But in many ways, the difference between the two matters greatly.
Saltwater is extremely corrosive, and to compensate for this reality, a few engineering details have to be present for the vessel to survive the harsh saltwater environment.
It is fine for a saltwater boat to head into freshwater but not good at all for freshwater boats to head out to sea. This is because of the difference in how they handle the important job of cooling the engine.
A boat that’s been prepped for freshwater use uses raw water from the lake or river it’s floating in to cool the engine. The engine’s water pump sucks up this water, circulates it through the engine, and spits it back out into the lake or river. This is an open loop cooling system.
A saltwater boat, however, has a closed-loop system. Similar to those used on cars and trucks, the water pump circulates coolant through the engine, and when the thermostat opens, it sends hot coolant to a seawater heat exchanger.
In principle, this is exactly like an automotive radiator, except that it is a water-to-water heat exchange rather than a water-to-air.
The seawater’s only job is to cool the closed-loop coolant on the other side of the heat exchanger’s walls. The two liquids never mix. The engine’s coolant is on a closed loop with the engine; the heat exchanger is on an open loop with the sea.
The reasoning is that if saltwater causes corrosion, it’s a lot cheaper to sacrifice the heat exchanger than the entire engine.
Corrosion and Anodes
Speaking of sacrifice, that’s the job of an anode. Usually cast from a metal like zinc, these anodes are connected to the boat’s electrical supply. Through electrolysis, the metal of the anode is “sacrificed” to the corrosion caused by salt water, which saves whatever metallic component it is attached to from suffering the same fate.
When you’re looking for a boat dealer in West Palm Beach, or if you’re searching for Robalo boats, make sure that yours is prepped for saltwater duty. If you head out into blue water in a vessel that hasn’t been properly prepped for it, you’re asking for big trouble.