Keeping a Boat In Saltwater

Saltwater can be highly corrosive and will destroy anything that is in constant contact with it, especially your boat unless certain precautions are taken to prevent it. Fortunately, there are steps that you can take that will save you money and add years of life to your Saltwater Boat. How do you protect your boat from the effects of Saltwater?

Flush & rinsed Outboard motor with freshwater inside & out-10-15 min after each trip Upgrade Cathodic Protection or use a Mercathode system Use an Engine Anti Salt Additive Use Anti-fouling Paint on boat bottom every 2 years Rinse trailer & flush brakes every trip Fix small cracks in fiberglass boats

Even if you can’t buy exactly what you need to run your boat in Saltwater here are the best ways to make the transition from Fresh to Saltwater and longer boat life.

 Freshwater vs Saltwater Boats

Freshwater in Inland water like lakes and rivers contains salinity or salt as in oceans and bays. Salt is corrosive to metals and other materials but other than dealing with salt there is not much difference between Saltwater and Freshwater boats, except offshore sailing boats that have a different Hull shape.

This is because they have a keel that makes them more stable in larger waves. In most cases, the main difference between the two is because of salt. Boats in saltwater corrode more quickly than those in freshwater. Salt eats away and corrodes iron and aluminum. If saltwater runs through the engine you’re boat experience galvanic corrosion which will destroy your engine’s ability to move and perform.

It can collect and crystalize and over a period of time kill it. Engine parts such as the block, exhaust, and manifolds, along with the driver and rise system are affected by saltwater. Luckily, there are ways to deal with the extra corrosion and control it. Because of the risk of corrosion and extra work and maintenance that’s involved Saltwater boats get a bad rep in resale and value.

In reality, if the Saltwater boats are maintained properly then they should last as long as a Freshwater boat. Upgrade your Freshwater Boat to a Saltwater Boat  To deal with the bottom fouling of saltwater you want to apply a layer of anti-fouling paint to your hull. Anti-fouling paint is an underwater hull paint made to protect from Salt corrosion.

Upgrade your Cathotic Protection or add a Mercathode system  New Mercury Mercruiser Quicksilver Oem Part 98869A14 Mercathode Kit. A Mercathode system is a cathodic protection system that runs a tiny electrical current through your engine block and outdrives. The electric current can stop galvanic corrosion of metal parts that are submerged. There are three types of Boat engines:

  1. Outboard engines
  2. Inboard engines
  3. I/O or Sterndrive engines – has the propeller on the outside, the engine block lies below the deck

They use two types of cooling systems

  • Raw water cooling system
  • The closed cooling system is the best way to go for Saltwater boats.

Raw water simply means the engine uses the water you’re running in to cool the engine. If this is saltwater, salt comes into the engine. Salt will cause galvanic corrosion, which basically means the engine will ultimately die. But first, it will perform less and less, until the salt collects inside the engine and crystallizes then it blocks.

I/O with cooling systems that use saltwater are the worst are worst kind of engine for saltwater usage. If you are using saltwater for the cooling system then you can expect to replace your risers and manifolds every 6 years or so. It can be expensive. An Inboard with a closed system is a preferable system for saltwater.

A Closed system uses its own fluids not salt water to cool the engine. Outboard engines don’t have it and because of this, the engine is susceptible to salt corrosion. They can be used in saltwater and pulled up when not in use as long as they are flushed out regularly after running them the motors will last.

Saltwater Boat Maintenance

Boats used in Saltwater have a shorter life expectancy than boats used in Freshwater. If well maintained, a Boat can last a long-time running and sitting in Saltwater if you use some protection. Taking the time for some maintenance procedures will make the difference.

Outboard Engines and cooling systems can corrode fast if not rinsed thoroughly with fresh water when used in saltwater. Rinse it every day you use it in the Ocean or Bay. The owner’s manual can show you how the best way to do this. Salt can and will build up if it’s not rinsed and destroy the inside’s surface.

All modern Outboards come with built-in garden-hose attachments, making the job of flushing easier. Some old-timer boater owners in the Keys use Dawn Dishwashing liquid when flushing raw water-cooled engines. I squirt about 3 OZ of Dawn in each flushing connection each time I flush and let it sit in the water jackets as the last step when I flush.

Using freshwater with the engine off and trimmed out of the water, simply run clean fresh water through the engine. Sterndrives, By contrast, might require more to transition to salt. Most modern marine engines have an enclosed-loop cooling system that uses a combination of raw saltwater and coolant. Sterndrives often don’t tilt out of the water, so unless your boat is trailered, stored on a lift, or in a rack, the outdrive (lower unit) may sit in saltwater.

Boats that are built for saltwater have cooling systems with the capability to flush out the saltwater on their own. As an extra precaution, they also recommend having the engine and cooling system rinsed down manually as well. There are additives that can be added to coat your engine that can protect the metal inside your engine and cooling system.

Use quality Additives to protect your engine like  CRC Industries (CRCSX-22) Salt Terminator, Cleaner, 22oz    That Cleans & protects anything exposed to salt (saltwater, salt air, road salt). Dissolves salt & leaves a protective coating to inhibit corrosion. Essential as a motor flush for marine engines in both saltwater and freshwater environments. Flushes marine engines, cooling systems, and heat exchanges; Cleans & Protects boats, PWCs, trailers, gear, fishing tackle, autos, RVs, trucks, tools, motorcycles, ATVs, bicycles, patio furniture & more!

Electrical wiring is also corroded and destroyed by the Salt as well and needs to cover and checked regularly. If you plan on converting your freshwater boat permanently into a saltwater vessel, you should consider replacing certain electronics with marine-grade systems. Check and rinse anywhere Saltwater can pool, like your bilge and enclosed tanks rinse it down.

Learn about Sacrificial Anode Systems and how they can save your boat with a minimal amount of money. There are many important parts of a boat that all have some functions that they perform.

One of the most important is the Anode System. It helps all other Boat parts function protecting them from corrosion by giving themselves up to corrosion.  If you’re transitioning your boat from freshwater to saltwater, you’ll want to replace the magnesium anodes with aluminum or zinc anodes for marine use and vice versa. Replace your boat’s anodes annually or when they are about halfway corroded.

All medal immersed in seawater produces an electrical activity called Galvanic Corrosion. Over time on a boat, it can lead to some serious problems with shafts, rudders or sterndrives and other parts.                                                  What is a Sacrificial Anode for a boat?

made from a less noble metal like aluminum or zinc. More electrically active, it protects the other two Metal Anodes when connected to them in seawater to make a circuit, & gives up its electrons, dissolving first, while preventing Galvanic Corrosion on boat parts.

So instead of swapping boat parts, you’re swapping a small Sacrificial Anode that is attached to the boat in the general vicinity of where the protection is desired. Sacrificial Anodes have a working life to them and will wear down and eventually be of no use leaving the boat owner at risk for damage to their boat.

They also have to be installed the right way or the same bad result will happen. Use quality bottom paint for your boat like Aquagard 10201 Bottom Boat Paint Waterbased 2 Gal Anti-Fouling – Black Marine RV Boating Accessories 

Before you put your boat in the water make sure the bottom has a fresh coat of paint. This will protect the Hull from the abrasiveness of the Saltwater and protect it from algae and barnacles. You need to inspect the Saltwater boat every chance you get and paint the boat every couple of years.

Another tip for Saltwater boat owners is to store them out of the Saltwater when out of season or not operating. anti-fouling paint is a necessity in saltwater unless you rack store or have a boat lift. Location is key, as marine growth in Florida, for example, is different than the Northeast or Pacific Coasts.

So get the info from other boaters in that area and the manufacturers on what works in that neck of the woods and what may not. This will reduce maintenance and operating costs. One interesting note is that colder freezing temperatures in saltwater is harder on boats and more corrosive than in milder temperature in parts of the country.

What Is a Sacrificial Anode


The boat dealer and manufacturer should have information on what kind of paint and Anode system could be right for your boat in your region of the country where you’re living. The same maintenance used for your boat should be used for the trailer. Protect your boat’s trailer by rinsing after using it with lots of freshwaters. Aluminum trailers are better for saltwater use than galvanized steel because they’re more resistant to corrosion. A couple of tips to use on your boat trailer:

  • Wash down the trailer soon after you pull it out of the water
  • Consider a trailer made of high-grade material like aluminum
  • Consider using Disk Brakes on the trailer because of their easy access to flushing with fresh water.
  • Use silicone grease to protect connectors from corrosion
  • Always do a general trailer check before leaving for the water, to protect your boat and your safety. Make sure your boat is level on the rests and the tie-downs are on and the brake lights are working.
  • Use the right hardware for the right temperature and salinity. Hardware and wiring that works on Chesapeak Bay won’t last in the Gulf of Mexico.
  • Check your tire pressure. Trailer tires are different from car/truck tires.  Check the tire sidewall for correct pressure (usually 50-65 psi.)
  • Use safety chains correctly. Chris-cross the chains below the tongue.  Position the hooks to your tow vehicle in such a way that they won’t easily “bounce off.”  Even better, use a closed-end fastened

How To Flush Out Saltwater From your Outboard Boat Motor


Jigging Fishing Techniques

Is Salt Water Bad For Fiberglass Boats


Fiberglass boats should last 50 years or more if taken care of right. Fiberglass is very durable and with proper maintenance and care, fiberglass boats can last for many decades. Fiberglass itself will not break down but instead will break down due to outside factors. Compared to other types of boats, especially wooden boats, fiberglass is much less maintenance.

This does not mean that there is no maintenance involved, and you must keep up with it. Most importantly when attempting to maintain your boat, you need to protect the bottom that is constantly exposed to water. If your boat is left in the water for even a few days, you will want to attempt to protect it from algae and other growth.

To prevent this there are certain protectants and paints you can apply. The area between the railing and the waterline will have to be regular maintenance spots because this part of your boat takes on most of the waves, spray, and sun. Without proper care, this area will fade, oxidize, and get hazy. To combat this wear, you need to make sure you keep up the wax on your boat. Some factors that will affect break down are:

  • Exposure to UV rays-too much UV can make fiberglass brittle and the fact that most boating happens in sunny weather it’s most likely the main culprit. Another problem that is associated with the sun’s effect on a fiberglass Hull is warping which can be expensive to repair.
  • Fatigue from movement– poor production of the fiberglass at the beginning will naturally catch up sooner than a better initial job, especially in the rough ocean. Repetitive waves and vibration impact weight will also catch up causing the fiberglass to wear and fail.
  • Water saturation can cause a breakdown between the fiberglass and the resin. This is most often caused by a formation of acid with the water and products hidden in the fiberglass. The resin in fiberglass is waterproof still after enough water is absorbed the damage will apply more and more pressure which can cause wear, blistering, and cracking. The part of the boat that is most susceptible to this damage is the part of the hull that is below the waterline.
  • Salt from seawater-Salt from saltwater can move between the fiberglass and become deposited in the larger porous areas of the fiberglass. This causes the salt to put pressure on the fiberglass.
  • Small Cracks-monitor your vessel for hairline cracks. Hairline cracks need to be filled or they will turn into bigger cracks and will eventually affect the integrity of your boat.

When you live down along the shore as I did, salt can become an issue for cars, siding on your home, patio furniture, boats, and marine equipment. It becomes highly corrosive in water and even in the air. The answer is always fresh clean water to wash it away.


What Kind of Anchor Do I Need


JimGalloway Author/Editor



references: Strong Marine-Maintenace Tips

Moving A Boat From Freshwater To Saltwater   from BoatUS Magazine




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