Freshwater Vs. Saltwater Boating: What’s the Difference?

Are you’re a freshwater boater trying to transition to saltwater for the upcoming summer? If yes, you definitely are seeking answers regarding the differences between boating these two different water types, aren’t you? Well, you’re at the right place!

Let’s discuss the differences between freshwater and saltwater boats and the boating experiences in these two.

For instance, how is maintaining a seawater boat different than maintaining a freshwater boat? Or, what are the specific set of skills required for seawater boating? Read on to find out!

Freshwater Vs. Saltwater Boats

1.   Hull Design:


The seawater offshore is rough and harsh. Therefore, many seawater boats are designed to withstand such conditions.

Offshore boats are designed to have a deep-V-shaped hull such that they cut through waves smoothly. Moreover, a transom deadrise of 21 degrees or more is preferable in the case of saltwater boats in order for them to handle waves in big water bodies efficiently.

On the other hand, mod V and flat bottoms shaped hulls are popular in freshwater boats. Flat bottoms have zero deadrises, which make them stable and easy to maneuver in small and calm water bodies.

And the mod V hull design offers stability and speed to the boat while allowing the boat to ride like a deep V at the same time. The deadrise is about 10 to 20 degrees in mod V hull design. V-hulls aren’t quite preferred in freshwater as they can scrape along the water bed in shallow water areas.

2.   Cooling system:


In raw water cooling system, fresh water or sea water is drawn from outside the boat, pumped through the engine block, and exhausted. Given how simple this cooling system is, it is the most common type of cooling system in freshwater marine engines.

The problem, however, occurs when you plan on using the boat with raw water cooling system in a seawater setting.

Sea water, with a salinity of 3.5% on average, is more corrosive than fresh water. The highly conductive chloride ion in saline water can easily penetrate through metal surface films. The buildups with the jacket restrict the water flow, which results in engine overheating.

Therefore, many seawater boaters prefer their engine cooling system to be enclosed type. This way, seawater doesn’t come in direct touch with the engine’s water jacket and flows through a heat exchanger instead. In this case, even if the buildups within the heat exchanger restricts the water flow, you’ll only have to replace the exchanger, not the entire engine.

3.   Mercathode system:


Mercathode system in seawater boats feeds off of boat battery to develop a protective field around the sterndrive unit against galvanic corrosion. This system reverses the blocking current, which blocks the destructive flow of galvanic current.

The anodes used in this system are either aluminum, magnesium, or zinc. While this system isn’t paid a lot of attention in freshwater boats, it is a quintessential corrosion protection system among seawater boats.

Zinc anodes are less resistant to electrolytes present in saline water and, therefore, sacrifice themselves to protect other metal parts.

Consequently, zinc is the most preferred anode for seawater boating, followed by aluminum. Moreover, when left idle and unattended for long, aluminum pacifies by forming an oxide coating on the surface.

However, given its high current output and short length, magnesium anode isn’t an ideal choice for seawater anode systems.

On the other hand, magnesium performs unbeatably when it comes to fresh water. Following the expensive magnesium anodes are aluminum anodes, which are great for both fresh water and sea water.

Freshwater Vs. Saltwater Boating

1.   Skills:


Needless to say, seawater boating definitely demands more maneuvering and navigating skills from a sailor. The water level goes up and down, and you need to face challenging tides and currents.

In the coastal environment, you must understand different channel markers and learn how to read radars and weather forecasts. When you’re boating offshore, weather can change quickly and viciously. You definitely don’t want to get caught in the middle of an angry storm offshore.

2.   Maintenance:


Salt water can be five times more corrosive than fresh water. Therefore, it is a no-brainer that a saltwater boat demands heavy maintenance relative to a fresh water boat.

Nevertheless, remember that it definitely doesn’t imply that fresh water boats are maintenance-free, and although less often, they also face the corrosion and hull bottom fouling issues just seawater boats do.

  • Flush your seawater boat with fresh water:

In order to prevent saltwater from corroding your boat exterior as well as the interiors, it is recommended you flush your boat engine and rinse the exterior with fresh water.

The good news is that many high-quality saltwater boats come with an internal engine flushing system these days. Not only the engine, other metal parts, including railings, brackets, propellors, and exposed bolts, should also be properly rinsed using fresh water after every saltwater use.

It is also imperative that you flush your boat engine in a way that’s recommended. It is a general rule of thumb that your run the fresh water for around 5 to 10 minutes to get a good flush, and after each flushing, manufacturers recommend that you drain the entire fresh water.

Especially if you plan on storing your boat for some time, this step is critical if you don’t want your boat metal parts rusty and damaged. Not only your boat your trailer can also take an intense hit from saltwater. Consequently, one must rinse their trailer well using fresh water after each use.

  • Replace your boat anodes as recommended:

Also, replacing your boat anodes annually or when they’re eroded or dissolved halfway through is essential for saltwater boat maintenance.

While one isn’t required to check how much their freshwater anodes have eroded frequently, in the case of saltwater boats, it is recommended you routinely check your boat anode status.

  • Paint your boat bottom with a good quality bottom paint:

Paint your hull using high-quality anti-fouling hull paint that is toxic to marine growths. Even if you sail in fresh water, this tip is definitely recommended.

3.   Fishing:


Now in this section, the saltwater wins hands down. It is an incontestable fact that saline water offers a diversity of fishes. Therefore, many fishers often prefer sea water fishing. If you’re a fisherman, let us know what your preferences are?

4.   Maintenance cost and resale value:


Boat storage around freshwater bodies is typically less costly than storage in seawater marinas. Also, the maintenance cost in seawater boats, given how complicated the systems and consequences can be, is relatively higher.

Furthermore, insurance in the coastal environment can be quite expensive, especially if you boat in a hurricane-prone area. Overall, maintaining a seawater boat is definitely more costly.

Now, when it comes to resale value, boats that have taken trips in sea water, given how quickly saline water can corrode and damage the interior and exterior of the boat, are often avoided by boat buyers.

However, if properly maintained, boats that have seen the coastal environment a few times can be in a good resale condition. And, if a freshwater boat that has never taken a trip to salt water is not given enough attention and maintenance, it will definitely be in a lot worse condition than a seawater boat.

Can You Use Freshwater Boats on Seawater or Vice-versa?


Boaters often want to change their boating location from time to time. And it is definitely okay to do so. However, there are some considerations that you need to keep in mind before you switch from freshwater to seawater or seawater to freshwater body.

In case you’re planning to use your freshwater boat in saline water, you need to make sure that you flush the engine using fresh water after every use. Rinse your entire hull and deck with fresh water to make sure that no saltwater remains to corrode your boat metal.

Moreover, you might want to make some upgrades if you permanently want to use your freshwater boat in seawater, for instance, getting a heat exchanger cooling system and upgrading to marine grade hardware, electrical wires, and appliances.

Also, as freshwater flat bottoms aren’t designed to tolerate the roughness of the sea, going far offshore in a freshwater boat is definitely not a smart idea.

On the other hand, the transition from seawater to freshwater is easier for seawater boats. Be wary of the water depth in shallow water, and you should do just fine.


We hope we could provide you with all the information regarding seawater and freshwater boating in this post. In short, while saltwater fishing is more productive and exciting relative to freshwater fishing, maintaining a seawater boat is much more demanding and costly.

Do you have any information on saltwater and freshwater boating that you’d like to share with us? We’d also love it if you could your experience in saltwater boating and how you maintain your boats. It would be incredibly beneficial for our fellow sailors!

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