Aluminum Boats in Saltwater: Everything You Want To Know
If you’re in the market for a jon boat for saltwater fishing you’re probably looking at an aluminum hull. They’re sturdy, usually well-priced, and they last a long time. A well made aluminum hulled boat can last much longer than boats made from wood or fiberglass but the initial investment will likely be a little higher. All welded aluminum boats made from quality aluminum can last for years, however. Especially if it’s well maintained. But, you’ll notice, these are mostly sold as freshwater boats.
It’s possible to use an aluminum boat in saltwater, but some extra precautions need to be taken. So let’s take a look at what happens when you take your aluminum boat out on the open sea and how you can ensure it will stay in good condition for many seasons to come.
What Happens to Aluminum Boats in Saltwater
The reason aluminum boats aren’t always recommended for saltwater use is that saltwater will corrode aluminum. But it’s not like the boat will melt as soon as it hits the water or anything, and there have been many methods for keeping an aluminum vessel seaworthy for years. You just need to know what happens and how to deal with it.
The major issue for your aluminum boat is galvanic corrosion. Saltwater is a corrosive electrolyte. When you place aluminum into a saltwater solution you set the stage for an electrochemical reaction.
When the aluminum in your boat is close to other metals as well as an electrical current, and heat as well, this reaction speeds up. So if your boat is connected to a power supply on shore, or maybe you have a loose wire touching the hull, you’re creating an electric field that allows for galvanic corrosion to occur.
A galvanic reaction like this is essentially what happens inside many batteries to create power. The current flows from one type of metal to another until one is basically used up and a current can no longer flow
How Different Metals React in Saltwater
Obviously most people aren’t making boats out of gold or platinum, but there is a hierarchy of metals and how they react during a galvanic corrosion situation. The more noble a metal is, the less reactive it is. This list shows, in order, active to noble metals. That means most reactive to least reactive.
- Stainless steel (304)
The further apart two metals are, the greater the reaction will be and the more the active, or anode, metal will corrode. You can see that if you have an aluminum boat with steel or bronze attached to the hull, you’re putting the aluminum at greater risk of corrosion. But if you have zinc anodes, the zinc will take the brunt of it and leave the aluminum safer.
The reason this is relevant to boating in general is that maybe you have a stainless steel prop. Or cleats. Or bronze accents. Or you’re in the dock next to a boat that has those things. If your aluminum boat is next to a boat with a stainless steel prop and there’s a current, your boat is going to be the one that suffers. So you need those anodes and a good paint job at the very least.
What are the Advantages of Using Aluminum in Saltwater?
It seems like aluminum is just a hassle at this point, but that’s not the case. It has some clear advantages for use in saltwater just as in freshwater.
- Despite what we’ve stated, aluminum is actually very good at resisting corrosion beyond saltwater. The natural oxidation of aluminum means aluminum oxide forms a strong coating on the metal that makes it very tough.
- Aluminum is very lightweight for the strength it offers, which is why we make so many things out of it.
- It doesn’t require a ton of maintenance. If you have a coating of good quality paint on your boat it’s already primed to endure a lot and will only require simple cleaning and upkeep
- It’s not as expensive as many other kinds of metals. It’s also significantly cheaper these days than similar boats made of fiberglass.
- Aluminum is durable. In rough conditions, aluminum can stand up to a lot, certainly better than wood or fiberglass boats in some cases.
- If you do get into an accident in aluminum vessels, the nature of aluminum works in your favor. The metal is strong but malleable. That means if you run into rocks, for instance, an aluminum boat is more likely to dent where a more rigid boat would crack. In general, aluminum boats are very safe and easy to handle.
How to Protect Your Aluminum Boat in Saltwater
There are a few methods of ensuring your aluminum boat can survive in saltwater. Let’s take a look at the most common ones.
Boats in saltwater require anodes. Anodes are just pieces of metal that are less noble than aluminum as we saw above, so zinc or magnesium. In this context, the nobility of a metal is important because it dictates a metal’s likelihood to corrode. If aluminum and steel are together, the aluminum will corrode and atoms will be stripped away, bonding to the steel. Eventually, enough is stripped away and the boat develops cracks, holes and weak spots as a result of pitting and aluminum oxide.
Boat makers try to design aluminum boats in ways that keep aluminum as far from other metals as possible. This means ensuring there aren’t places where water can gather and pool. Zinc, as we saw, is more reactive so this sacrificial anode is designed specifically to corrode. It bites the bullet in place of the aluminum, so to speak. Eventually all the zinc will be eaten away and you’ll need new anodes.
It’s good practice to ensure you regularly inspect your anodes. Give them a quick look every time you head out and when they start falling apart noticeably, have them replaced. You can get cheap zinc sacrificial anodes for just a couple of bucks.
Protective Paint Coating
The most effective method of protecting aluminum in saltwater is a protective coating. Paint designed for aluminum boats provides a barrier between the metal and the corrosive effects of salt water. In fresh water you can keep your aluminum boat bare and plain if you like, and some boaters choose to do this. But in salt water it’s definitely not recommended. A good aluminum paint can fill any cracks and crevices around rivets or welds to keep out saltwater completely and greatly extend the life of any boat.
Painting an aluminum boat can be a bit of a chore if you’ve never done it before so if you are doing it yourself, make sure you prep it properly. That aluminum oxide coating we mentioned before needs to be dealt with first. And you’ll need to make sure you have the right paint. Something designed for use on aluminum boats, like an anti fouling paint specifically, is very important, otherwise you risk the paint not adhering or not working right and wasting your time and money. Check out our guide on how to paint an aluminum boat for more.
Paint will always scratch and crack over time or with damage, but it’s the best first line of defense and more paint can always be applied to patch up problems. Regular inspections are important to look for abrasion damaged from scratches and general wear and tear.
Electronic Corrosion Inhibitors
These are electronic devices that work in conjunction with your anodes. They sort of create a negative bubble of current around things like your outdrive or prop that negates the current that drives the galvanic corrosion reaction in the first place. You can think of it like a dimmer switch that reduces the overall effect. Corrosion will still occur but it’s very much reduced while these and your anodes are in good working order.
This will be much easier if you’re using a small aluminum jon boat as opposed to something like a larger pontoon or bay boat. But whatever the kind of boat, it’s good to keep it as clean as possible in between uses. Take your aluminum boat out of the water and wash it down with fresh water. Sometimes as simple as rinsing all the saltwater off of your boat can extend the life of an aluminum boat by years. It only takes a few minutes and is probably one of the best ways to counteract the potentially harmful effects of saltwater.
You can buy solutions at marine supply stores, or even online at places like Amazon, that are designed to remove salt residue from boats. Most of these solutions can be sprayed on and then rinsed off and will leave a protective coating on the hull that limits the effect saltwater to prevent further corrosion. It can also be used on trailers and your car if you’re in a northern area that salts the roads.
As a boat owner you should be inspecting your boat pretty regularly whether you boat in freshwater or saltwater. But if you have an aluminum boat and use it in salt, just kick those inspections up a notch. You’ll want to check the hull on a regular basis, just a quick look over the exterior and interior, especially in welds, joints, corners or any place where things are attached to the hull that could be weak spots in the paint and will allow salt exposure. Look for signs of corrosion and damage and if you notice anything get it cleaned up right away so it can’t get out of hand.
If you’re using a jon boat this can be a process that really only takes a few minutes and is well worth the time. Give it a thorough inspection when you’re trailering the boat, check out the bottom and the motor mount and so on, see what’s damaged and figure out how to repair it. It’ll save you a lot of time and money in the long run to catch issues when they first develop and are still small and manageable.
Limit Metal on the Boat
The less metal you have on an aluminum boat the less galvanic corrosion will occur. So make use of things like silicone sealed nylon plugs, nylon washers and so on to keep less stainless steel or other metals from causing a reaction and protect aluminum as best you can.
The Bottom Line
Saltwater has the potential to cause havoc on an aluminum boat but it doesn’t have to. Prevention and maintenance together can ensure your aluminum boat handles the sea as well as any lake.
Make sure your boat has a protective coating to limit exposure to salt water. Keep sacrificial anodes up to date around the hull even if you don’t have any different kinds of metals on your hull – other boats will.
Keep your boat well clean and well maintained to limit exposure, and use some other methods like salt sprays or corrosion inhibitors to prevent galvanic corrosion from damaging your hull.
Categories: Jon Boats