Freshwater vs Saltwater Boats – What’s the Difference?

Freshwater vs Saltwater Boats - What's the Difference

Are you torn between getting freshwater or saltwater boats for your fishing or boating trips? Or are you wondering whether you can use your current boat on saltwater and freshwater? Boats can be very expensive and you wouldn’t want to get the wrong boat or damage your existing one because of misuse.

Whether you are thinking of buying a new boat or just interested to know whether you can use your current one for both freshwater and saltwater, it is important that you know the difference between saltwater boats and freshwater boats. So, let’s differentiate the two and find out how types of water can affect each boat.

Saltwater vs Freshwater

Saltwater vs Freshwater

What is a Freshwater Boat?

A fresh water boat is a vessel that is designed for inland water or freshwater (also called sweetwater). Examples of inland waters are lakes, bays, rivers, canals, inlets, and watercourses. They can come in different shapes and sizes as well as functions. Most freshwater boats have hull shapes and fins that are meant to handle flat waves.

What is a Saltwater Boat?

A saltwater boat on the other hand is one that can be used for seas and oceans. These bodies of water have higher salt content. Saltwater boats are designed to be tougher so they can withstand the effects of salt and prevent salt corrosion. They are also built to hold out against rough waves and rocky shores. Some electronic systems used in freshwater lake boats are not capable of repelling saltwater.

How Freshwater and Saltwater Affects Boats

How Freshwater and Saltwater Affects Boats

Both saltwater and freshwater can have an effect on your boat’s structure. This is why it is advisable to use a watercraft that is intended for a specific type of body of water if you want your vessel to last longer. However, if you’re forced to use a freshwater boat in saltwater, be sure to take the necessary maintenance and cleaning to avoid damaging your watercraft.

If you have a sweetwater boat, make it a habit to regularly check your boat’s hull to see if there are blisters on it. It is very common for freshwater boats to develop blisters or what they also call chickenpox on the hull. Although this can be easily fixed on your own as long as you have the right tools and materials, it can still be a pain and can be expensive when not treated early on.

Saltwater boat owners on the other hand should look out for barnacle and algae buildup. Barnacles only exist in saltwater and never in freshwater. This can cause damage to your hull if you wait too long to get rid of them.

Another effect of saltwater on boats is that it can corrode metal due to the high salt content in the water. Saltwater corrosion is ten times faster compared to freshwater. One way to ensure that your boat won’t be damaged easily is by investing in a high-quality boat and through proper maintenance.

Key Differences of Freshwater and Saltwater Boats

Key Differences of Freshwater and Saltwater Boats

Freshwater and saltwater boats are designed to function well for a specific body of water. Due to this, there are certain differences in how they are built and constructed. Here are some of the differences you need to understand about your boats.

Engine Cooling System

Saltwater boats have cooling systems to safeguard the engine from corrosion by the salt. These systems help in flushing out the engine after saltwater runs. They are designed with self-flushing capabilities so you do not have to manually flush your system.

Boats intended for freshwater conditions do not have this flushing system, so you need to manually flush it if you try your freshwater boat in saltwater. The advantage of having these cooling systems is that you can leave your watercraft in salt water for a longer period of time without worrying about corrosion.

When using freshwater boats in the ocean, test your boat first if it can handle bigger swells and larger waves before speeding up and try to stay closer to the shore first. A VHF radio will be handy in case something happens to you.

Three Types of Engines

If you intend to use your boat in saltwater boating permanently, you need to be careful with your engine. It is recommended to avoid I/O engines that have raw water cooling systems. Better to opt for an inboard engine that has closed cooling. To learn more about this, here are the three types of engines and how they work.

Outboard Engines

An outboard engine is okay for saltwater boating if you won’t use it regularly. This is because you can remove them from the water while not in use. This means that even if you leave your boat in salt water for several days your engine will not be soaked in the water at all times. However, you still need to flush your engine, or else you’ll still need to undergo serious maintenance that can be very expensive.

woman in waterInboard Engines

If you plan on running boats to saltwater permanently, your best option would be the inboard engine with a closed cooling system. This means that the engine uses its own cooling fluid, so it doesn’t need salt water to cool the engine. Having a closed cooling system will avoid engine salt corrosion. The main difference between an outboard motor with an inboard engine is that outboard engines do not have a closed cooling system.

I/O or Sterndrive Engines

This should be the least on your list if you plan to use your boat in the sea frequently. I/O or sterndrive with raw water cooling is the worst option for salt water boating, if you use this you would need to replace your manifolds and risers after every 6 years or less. This can be very expensive and you cannot always guarantee that the parts are available all the time.

These engines can use two kinds of cooling systems, either raw water systems or closed systems. A closed cooling system also has two types. One uses closed cooling for exhaust and the other one runs coolant via the block and not through the risers and exhaust manifolds.

Hull Design

Since freshwater boats are designed to move easily through flat shores and manage flat waves with ease they have fins and hull shapes intended for freshwater boating. Saltwater boats experience rougher conditions and rocky shores, thus their hull shape is designed to withstand rougher waters.

However, this does not mean that you cannot use your freshwater boats for saltwater boating. You only need to be more careful and try to choose the best time to go boating when waves are smaller and the water is calmer. Avoid using a boat made for freshwater conditions when there are large waves as the ride will not only be rocky but can also be very dangerous.

Hull Fouling

Saltwater boats need better maintenance because they are more susceptible to the growth of algae, barnacles, and other marine life. These aquatic lives can attach themselves to the boat’s hull and can do serious damage like hull fouling if not treated or removed right away.

One of the common issues for boats used in freshwater lakes in the formation of hull blisters. This can happen because of the gel coat that absorbs the water. Similar to saltwater boats, it can do serious damage to your watercraft when not treated immediately.

Mercathode System

Most boats intended for saltwater use have Mercathode system. This system protects the boat engine from suffering galvanic corrosion. Having saltwater in your boat’s engine can block it completely and damage it which can affect your boat’s overall performance.

How to Manage Saltwater Corrosion

How to Manage Saltwater Corrosion

This is a common problem that most boat owners face. However, there are ways to deal with it and you can even convert your sweetwater boat for saltwater use. A well-maintained saltwater boat will improve your boat’s lifespan, although it may still cost you a lot.

In order to deal with such corrosion, you need to take a closer look at your systems and would probably need some system upgrades. Installing a Mercathode system will help block saltwater from getting in your engine. It’s a cathodic protection system that will help prevent galvanic corrosion.

You can also replace your fasteners with anodized coatings, stainless or other metals. If you don’t plan on getting the closed cooling systems then you need to install a freshwater flush system. The best thing to do is installing a closed system if you do not have outboard boat motors.

Saltwater vs Freshwater: How to Protect Your Boat

Saltwater vs Freshwater: How to Protect Your Boat


Anodes are used to protect the metal components of the boat that have contact with water. They draw electrical currents directly to themselves to protect your boat parts. When moving from freshwater boating to saltwater, you may need to switch from magnesium anodes to aluminum or zinc anodes or the other way around. It is recommended to change your anodes when you see that they are corroded midway or at least every year.

Rinse and Flush

To keep your boat in great condition, especially those that are used in saltwater boating, it is ideal to rinse your boat as soon as you get back to the shore or dock. All parts that was in contact with salt water should be rinsed thoroughly and other parts where water can pool.

If you used a fresh water boat to saltwater then you have to flush the engine manually for about 5 to 10 minutes or depending on the manufacturer’s manual.

Inspect the Bottom Paint

It is a must to ensure your boat has a fresh coat of bottom paint, especially if you’ll run your boat in saltwater. You may not need a fresh coat of bottom paint for freshwater boating. But it is still advisable to check on them every once in a while. You can use anti-fouling paint for the bottom of your boat.

Trailer Care

Just like your boat, you also need to take care of your trailer. Whenever you use your boat in saltwater and freshwater, you also need to rinse all parts of your trailer to prevent corrosion. Go for galvanized steel if you frequent the saltwater as it has better corrosion resistance than aluminum trailers.

If you use drum brakes on your trailer, best to get a drum brake flush kit, this will extend your brake’s life. Most boat owners prefer drum brakes because they are less expensive.

Frequently Asked Questions

Freshwater vs Saltwater Boats Frequently Asked Questions

Can I use my freshwater boat in saltwater?

It is possible to use freshwater boats in saltwater. However, there are certain things you need to do to minimize damage to your sweetwater boat. After using your boat in saltwater, be sure to flush out the engine and wash the hull to remove any leftover salt.

What is the difference between a freshwater boat and a saltwater boat?

A freshwater boat is designed to be used for freshwater which is inland water. They normally have fins and hull shapes that are designed to manage flat waves and to be close to flat shores.

A saltwater boat is designed to be used for seawater which has more salt. In general, they need to handle corrosion. Salt water boats may also require a regular maintenance routine than freshwater lake boats.

Are saltwater boats more expensive?

Prices for boats vary depending on function, type, materials used, and construction. Most saltwater boats can be more expensive because they need to be tougher and designed to withstand salt corrosion.

Can you take any boat in the ocean?

Most of the time, any boat can be taken to the ocean so you can use a freshwater boat. The only thing is, boat owners should be aware that not all boats can handle rocky shores and rough waters. If your boat is not designed for that, be sure to take extra precautions to avoid accidents and injuries.

How much are freshwater boats?

The price for freshwater boats has a wide range. Depending on whether you want to buy a brand new freshwater boat or a used one. The price can range from $1,500 to more than $100,000 depending on function, brand, and model. A larger boat is also expected to be more expensive.


So, what can you say about their differences? Boat buyers should be very clear on how and where they want to use their boats. A few things to remember when purchasing a vessel is to consider where and how you want to use your watercraft, not all boats are designed for both fresh water and salt water, consider the hull design, flushing systems, and corrosion resistance. Boats for freshwater use would need extra maintenance after each use in saltwater to prevent serious damage in the future. Also, never leave your freshwater boats on saltwater for long periods of time. You can check out the best boat report to get the latest news in the boating industry.

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Lisa Hayden-Matthews

Lisa Hayden-Matthews

An avid Skier, bike rider, triathlon enthusiast, amateurish beach volleyball player and nature lover who has never lost a dare! I manage the overall Editorial section for the magazine here and occasionally chip in with my own nature photographs, when required.

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