All About Boat Bottom Painting

Your boat is a big investment, and chances are you try your hardest to take the absolute best care of it, in and out of the water! You might perform regular maintenance on your boat and trailer to keep your investment and your loved ones safe. However, how often do you stop to ponder what's going on with the bottom of your boat? 

Here we dedicate this article to all about boat bottom painting and teaching you what you need to know!

What Is Boat Bottom Paint? 

Bottom paint is also called anti-fouling paint. The goal is that the paint will deter the growth of plants, algae, barnacles, and other aquatic invasive species that might latch to your boat's hull when it is sitting in the water for an extended time. Usually, bottom paints accomplish this by using a biocide, traditionally copper. Generally speaking, the more copper or other biocides a paint contains, the more effective and costly it is. Due to environmental concerns, many marinas ban copper due to the damage it causes while leaching into the water. Many boaters now opt for eco-labeled bottom paints with little or no copper. But we will talk more about that a little later! 

Who Needs Boat Bottom Paint?

Boat bottom painting is something you might want to consider if your boat stays in the water regularly for long periods. For example, bottom paint is a good option if your boat stays in the water year-round or during the majority of boating season! Conversely, bottom paint is unnecessary if your boat is primarily stored out of the water and only sits in the water for short periods. For example, if your boat is in the water for a two-week summer vacation or the occasional weekend trip, applying a quality coat of wax as a protectant and regularly cleaning the hull after a trip is typically all that's needed to keep your hull clean.

If you are currently considering bottom painting, but are on the fence about it, know that once you make the plunge and apply the paint, you can't go back. Periodic bottom-painting, cleaning, and refreshing are now a permanent part of your boat's routine maintenance schedule. Also, consider that potential buyers might think applying bottom paint is a negative if you want to sell in the future. 

Honestly, trailerable boats are better off without bottom paint. However, if you need to paint your trailerable boat, consider a hybrid paint – see below for more details!

How Often Do You Apply Boat Bottom Paint?

As a general rule of thumb, you should apply boat bottom paint annually. However, certain bottom paint types and brands boast lasting for two years. Therefore, it is a great idea to examine your boat's hull annually to determine if it needs another coat of paint. A tip is to choose alternative bottom paint colors so you can easily see when the newest paint layer is thin and becoming ineffective. Another tip is if your boat has not been in the water for a long time, take an abrasive scrub pad and scrub off the ablative paint surface to refresh the effectiveness of the paint.

What Type Of Bottom Paint Do I Choose? 

Well, the answer to this question is not quite so simple. A number of things influence what paint is best for you. Things like the type of water you boat in, how you store your boat, and how frequently your boat is in the water all influence your paint choice. So let's take a quick look at a few common ways people use their boats and the correct bottom paint for each use.

Your boat stays in the water and sits.

If your boat stays and sits in the water, then you need "hard" bottom paint. In addition, hard bottom paint (modified epoxy or non-sloughing paint) is your best choice if you have a high-performance boat. Hard bottom paint is optimal for powerboats and racing sailboats that stay in the water because it does not keep its anti-fouling properties when kept out of the water. The copper biocide slowly wears away in a hard bottom paint instead of the paint itself. Hard bottom paints form a strong, durable coating that does not wear away. A disadvantage of hard bottom paint is once the copper biocide wears off, the strong, tough coating is messy and difficult to remove – especially if you have multiple layers that have built up over the years. Over time, the accumulation of paint will become so thick it will start to crack and peel, meaning you will need to have your hull completely stripped and begin again. 

You frequently use your boat, but it is in and out of the water.

If you use your boat regularly and pull it in and out of the water, then an "ablative" boat bottom paint is an excellent choice! Ablative (also called self-polishing) bottom paint gradually wears off as your boat moves through the water. Ablative paints also keep their anti-fouling properties even when out of the water, which makes them ideal for trailered and lifted boats. It constantly releases fresh biocide, like a bar of soap that wears away each time you use it! As the paint sloughs off, it exposes fresh paint that gives your bottom continuous protection. Putting your boat back into the water softens the paint, and the protection activates again. 

There are several advantages to this paint. First, as long as the paint remains on your hull, you know it's working to prevent growth. Another benefit is that as it's constantly wearing away, there's no buildup of old paint, which can be a pain to remove when the time comes. 

There are also several disadvantages to this paint. Ablative paints are less effective if your boat remains idle for extended periods because the lack of water movement prevents it from self-cleaning. Also, the self-cleaning feature is not a good choice for fast-moving boats, as the speed will accelerate the ablation process and cause rapid paint loss.

You don't use your boat often.

If you use your boat infrequently or you take your boat in and out of the water regularly, semi-hard ablative paint is not the paint for you. A semi-hard ablative (also called hybrid) paint will hold up better throughout the constant launch and haul-out cycles, unlike most hard paints that can't tolerate being out of the water for extended lengths of time. Semi-hard ablative paints are the perfect combination of ablative and hard paints. They offer a hard, strong, smooth surface that resists buildup yet holds up to faster speeds and repeated haul-outs without loss of protection. 

Bottom Boat Painting Tips 

• A very important tip to note, regardless of how often you use your boat, never use a copper bottom paint on a metal surface – like an aluminum boat, pontoons, exhaust, or motor parts. The copper will create a chemical reaction and will corrode the metal. Instead, use anti-fouling paint designed specifically for metal.

• If you feel unsure about what paint to choose for your particular area and boat, your local boatyard manager is a valuable resource. In addition, fellow boat owners can offer practical local knowledge about what paints work best in your area. Finally, many bottom paint manufacturers, such as Interlux and Pettit, offer online charts and tables to help you select the perfect bottom paint for your needs.

• The type of water plays a role in your paint choice, from freshwater to salt water. Boats in freshwater and brackish water can usually get away with cheaper or less expensive bottom paint. 

• The water quality where you will store your boat matters! If you keep your boat near golf courses, parks, at the end of canals, or other areas without water movement, you might need to paint with newer biocide-based paints. 

• Storing your boat in or out of the water impacts what paint you opt to use. Boats kept in or out of the water require specific paint types to prevent the paint from hardening and failing after being out of the water for long periods. 

DIY VS A Professional

It is entirely possible to paint the bottom of your boat yourself and to do it well! If you opt for a DIY boat bottom painting job, it is extremely important you take the time to fully educate yourself on all the do's and don'ts of the process so you don't end up with costly mistakes. We understand the biggest appeal to a DIY job is saving money! And while it's a messy, tedious job that isn't fun by any stretch of the imagination, it isn't brain surgery. 

Factors to consider before opting to paint it yourself or have a professional help is what type of paint you will use. While water-based paints are very effective and less toxic, specific boat performance applications require a more toxic paint. If you choose petroleum-based paint, you'll need a respirator. In addition, the dust from sanding boat bottom paint is toxic, and you will need to wear safety glasses, a mask to help protect your lungs, and gloves when working with the paint. Finally, many bottom paints are toxic. Some even require a pesticide license or other special permits to apply.

Another important consideration is the paint manufacturer's warranty. For example, will the paint manufacturer still warranty the paint if you apply it instead of a professional?

There are several pros to hiring the pros. Your time is valuable. Professionals can save you hours and hours and get better results. Professionals have a special stand to hold the boat, making the paint job efficient and even. In addition, if your boat has a layer of old paint to remove first, you will need a professional shop with specialized equipment to blast off the old paint using methods that ensure the fiberglass is not damaged.

Positives of Boat Bottom Paint

The obvious positive of painting your boat bottom is reducing maintenance by combating invasive species attaching and growing on the bottom of your boat. Let's talk about a few specific reasons why boat bottom paint is helpful.

1. Saltwater Problems

If your boat sits in saltwater, barnacles will pose a problem. While barnacles won't damage the gel coat of your fiberglass boat, removing them usually does!

2. Wooden Boat Problems

In wooden boats, aquatic organisms can dig right into the wood and cause severe damage to your hull.

3. Freshwater Problems

In freshwater, plants, algae, and zebra mussels will easily attach to an untreated bottom and pose constant maintenance.

4. Performance Problems

Zebra mussels, algae growth, and barnacles all add drag to your boat, dramatically affecting your boat's performance.

5. Maintenace Problems

Finally, getting those little buggers off is a pain and adds a continuous ongoing maintenance chore. In addition, they can damage the hull of your boat costing you a lot of money!

Negatives of Boat Bottom Paint 

There are several important negatives to note when deciding whether or not to paint your boat's hull. Let's take a look at the big ones!

1. Boat Bottom Paint May Poison You and Others

As you saw when we talked about whether or not to hire a professional, anti-fouling paint is highly toxic. Not only is it harmful to marine life, but it is also very toxic to humans. In fact, Britain and Europe have a new Biocidal Product Regulation that requires the active ingredients in anti-fouling paint to go through a reauthorization process. Manufacturers warn you to keep these chemicals as far away as possible from your body! In addition, many boatyards no longer allow boat owners to DIY paint their hulls to help ensure your boat meets proper standards.

2. Boat Bottom Paint Poisons The Waters Your Boat Goes In

Most people who own a boat have one because they love the water! It is never a boater's intent to destroy the very places they love. However, the copper in your paint has a purpose – to stop living creatures from making a home on your boat. The biocides in the paint will leach into the water. Experts estimate that bottom paint releases two pounds of copper annually for a 30-foot boat. Now imagine a marina with hundreds, or thousands, of boats moored in it, and you can see the problem.

3. Extra Maintenance 

Chances are you want to reduce the amount of maintenance required to enjoy your hobbies! Once you apply bottom paint, you will need to repaint it annually. After that, it becomes a never-ending cycle of cleaning and re-applying. 

Final Thoughts

Boat bottom paint helps boats that remain in the water long-term, but it is a big decision to make, especially considering the environmental impacts. You need to weigh the disadvantages and benefits for yourself, as without protective paint to inhibit aquatic growth, damage to your boat's hull is inevitable.

We hope our article gave you a comprehensive overview of boat bottom painting. Take a few minutes to talk to your local marina and local boaters to hear their thoughts! Here at Rocket Marine, we not only offer quality boat trailers but also pride ourselves on keeping the waters we love clean and pure and the boaters who love the water safe!

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