Difference Between Saltwater And Freshwater Outboard Motors

Difference Between Saltwater And Freshwater Outboard Motors

Let me guess!

You have been boating on freshwater (lakes and rivers) for years, and now wondering if you can push it further and go to saltwater with your outboard.


As it’s a boat, it technically can run in both freshwater and saltwater, but there are some thoughts worth considering before you approach saltwater.

However, as you are concerned with an outboard motor, things are a bit complicated when you use it on saltwater. Not all water is equal; therefore, you cannot simply drop your freshwater outboard in saltwater.

In this article, we will discuss the Difference Between Saltwater And Freshwater Outboard Motors, and why one cannot just go from one to another without doing some modification to the boat’s crucial parts.

What Is Saltwater and Freshwater Outboard Motors?

Let’s start the discussion with the easiest one. Freshwater motors are designed to run on freshwater. The parts are corrosion resistant and easy to maintain. To keep the motor cool, it draws water from freshwater and expels by allowing the water to run through the cooling system.

As far as saltwater outboard motors are concerned, construction-wise, these motors are more complicated. Saltwater corrodes metal 10 times faster compared to freshwater, so the parts of the engine are corrosion-resistant. It requires very careful maintenance to keep the motor running in good condition.

Due to the properties of saltwater, the motor contains more stainless parts than a freshwater one. One of the most distinguishable characteristics of saltwater motors is that they mostly have 25 to 30-inches of shaft.

Difference Between Saltwater and freshwater Outboard Motors

Having an outboard motor makes it easy to transit saltwater usage. However, you still require to take some hassle when using the boat on saltwater. Let’s have a look at the differences between these two conditions.

Water Cooling System

The motor gets hot while running. Therefore, it needs to be cooled down to roam in the water for an extended period. The cooling system draws water directly from seacock while on-the-go. It completes a heat transfer and allows the motor to expel water through the cooling system, and makes the motor run in a cool or warm state.

For using the boat on saltwater, the cooling system is pretty much the same, except for flushing the motor after every use. When you are done on saltwater, you need to come on freshwater and allow the freshwater to go through the motor’s cooling system to flush it.

Docking in saltwater on a regular basis requires the boat to have a closed cooling system. If you want to dock your freshwater boat in a lake, the raw cooling system will be enough; but you have to flush it regularly.

Rinse and Flush

Flushing with fresh water is a must, as saltwater highly contributes to corrode metal more than freshwater. It can wear out your outboard’s components much quicker compared to freshwater.

After boating in the ocean, you need to go through freshwater to rinse and flush the boat as well as the motor before getting back to the dock. When you daily rinse and flush the outboard using freshwater, it will get off the salt crystals of the boat surface, and make sure everything looks nice.
Besides, it will protect the internal parts, as well.

Boats that are designed explicitly for saltwater have a cooling system that doesn’t require manual flushing to protect the corrosive damage of saltwater.


As salt is very corrosive to metals, thus, if you own a freshwater boat that runs on saltwater every now and then, it will shorten the lifespan of the motor. The expected life of a raw water outboard motor is up to 1,000 running hours.

Even if you flush the motor cooling system through freshwater after every use, still it will take some damage.

Anticorrosive Materials or Parts

The exterior parts of a saltwater outboard are made of high-quality stainless steel, which is corrosion-resistant. This is something you will not find in freshwater boats.

To confront saltwater, sea boats have sacrificial anodes, which is a special grade of metal. This anode takes all corrodes on its surface by covering the motor and other valuable parts of the outboard. All you need is to replace the anode periodically to protect those parts.

Freshwater outboards are made of aluminum parts, which stands quite good to tackle corrosion. However, aluminum is too weak to withstand saltwater.

Hull Construction

Another important thing to consider before deciding is, how further you will go in the ocean, and how the boat is designed. Freshwater boats deal with comparatively small waves. So, this type of outboard has a close hull design.

However, I’m not saying your boat cannot handle the waves of the ocean, and you have to buy a new boat to ride into the ocean.

But, you should be careful about the ability of it. The boat will do fine into the ocean when there are small swells; be sure about the weather before you decide to use it on saltwater.

If the weather isn’t favorable, freshwater hulls will give you a rough ride and reduce the lifespan of the boat, as well.

So, if you are going to use the outboard on saltwater on a regular basis, upgrade the hull construction to be able to handle ocean waves.

Electronic Systems

Certain electronic systems aren’t designed to withstand saltwater conditions. If you are about to convert your freshwater boat into a saltwater one, you will require to compromise with some of the electronic items, and replace them with marine-grade ones.


Boats used in freshwater have a longer lifespan than boats in saltwater. So, if you are thinking about purchasing a second-hand saltwater outboard, it wouldn’t be worth the deal as the lifespan has already been compromised. Therefore, buying a new saltwater boat is recommended if the budget isn’t a problem.

However, if you convert your freshwater boat to use on saltwater and adequately maintain, rinse, and flush after every use, the boat will do fine.

Final Words

Whether it’s freshwater or saltwater, to make the boat run excellently in all conditions, you must ensure its maintenance part.

As far as going in the ocean occasionally is concerned, make sure you rinse and flush the system with fresh water after every use.

On the other hand, if you are considering to use the boat on saltwater more often, it would be better if you upgrade hall construction, add anodes electronic systems, paints, cooling system, and other essential parts to deal with the oceanic vibes.

Resources & References

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Hi, I’m Adam Vachon, an avid learner and working in the product marketing niche for the last few years. The problem I faced when marketing products for manufacturers made me interested in starting GearsLoft.

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