If you are a boat owner, you are well aware that regular maintenance is crucial for keeping your boat in top condition. One important aspect of this maintenance is applying antifouling paint to the bottom of your boat. This chore prevents marine growth and enhances the speed and ease of your boat's movement through water. While many boaters prefer to have professionals handle this task at a local boatyard, if you have the time and interest, you can try it by following this 10-step quick guide. More detailed information for each step is also provided to assist you in successfully completing the job on your own. By doing so, you can achieve both personal satisfaction and cost savings. As a general estimate, for a 26-foot boat, between paint, sandpaper, paint brushes, tape, and cleaning supplies, the cost of bottom paint would range from $425 to $925 for a high-quality finish. Additionally, keep in mind that you will need to repaint the bottom of your boat every few years - so doing it yourself will save you some money in the long run.
Now that we've got the basic steps down let's explore the process a little more in-depth, followed by some helpful information on how to choose the right antifouling paint for your boat.
Also known as antifouling bottom paint, boat bottom paint is specially formulated to keep marine organisms such as barnacles, plant growth, zebra mussels, and algae from growing on the bottom of your fiberglass, wood, or aluminum boat. This is done through the controlled release of biocides – most commonly cuprous oxide (copper) or the more environmentally friendly Zinc Omadine™ slime fighter, Biolux® zinc pyrithione and/or the hard shell deterrent Econea™. Antifouling bottom paint helps prevent hard and soft marine growth from attaching to the bottom of your hull, slowing you down, affecting your ability to maneuver safely, and costing you more in bottom cleaning, blister repair, and fuel bills. There are several categories of boat bottom paint:
Ablative bottom paint (also referred to as self-polishing) gradually wears away, exposing fresh biocide every time you move your boat and eliminating heavy paint build-up over time. It's not recommended for fast boats (moving at over 15 knots in most cases) as the paint might wear away too quickly, boats that sit at the dock for extended periods of time (the paint won't wear away, exposing new biocide) or boats that spend a lot of time out of the water. When applying new copolymer ablative paints, it's helpful to change the color, allowing you to easily see when it's time to repaint as the original color begins showing through. This can also help you identify high-wear areas that may need an extra coat. Sanding bottom paint also creates toxic dust, so use a dustless sander. And protect your exposed eyes, skin, and lungs with high-quality protective equipment before you begin sanding.
Hard bottom paint (also referred to as a modified epoxy coating) slowly leaches biocides over the life of the paint. When the antifouling agents are gone, the paint is still present on your boat – it does not slough off like ablative bottom paint. This hard coating is a better choice for fast-moving boats or for racers who desire a super smooth, fast coat of paint. It is also good for boats that sit at the dock for extended time periods. The downside is that since it doesn't wear away, each new coat means added weight, and eventually, there will be enough build-up that the entire bottom will need to be stripped down to the epoxy barrier coat. Bottom paint is recommended for any type of boat, including pontoon boats and fiberglass boats, as it helps prevent oxidation and discoloration of the hull. Regularly applying bottom paint is crucial to protect your boat from the corrosive effects of salt water.
Hybrid bottom paints usually incorporate the best of both styles into one paint by being lightly ablative and resistant to buildup but still providing a smooth, hard surface – a great option for high-speed boats.
Now that you know the different categories, which one is right for your boat? Your decision will be greatly affected by what paint you currently have. Since not all paints are compatible – it's important to study the manufacturers' compatibility charts before you buy. In general, you can apply ablative paint over a properly prepared hard paint, but you can NOT apply a hard paint over an ablative paint since the hard paint will not adhere properly. If you want to switch from ablative to hard paint, you will need to remove all of the previously applied ablative paint before proceeding.
If you're unsure of the manufacturer or what type of paint you currently have, you can at least identify whether it's ablative or hard by checking to see if it rubs off easily. If it does, it's likely ablative – if it doesn't, it's probably a hard or semi-hard hybrid paint. We highly recommend consulting with the boatyard manager if you have any doubts about your options. They know and understand the unique challenges of the area you operate your boat in and can likely provide excellent guidance on your best options, including how much paint you'll need to do the job.
We should also note that in some areas, copper-based paints are in the process of being phased out – so make sure to check your local regulations before choosing your paint. Fisheries Supply is proud to offer a variety of copper-free alternatives from several of our paint manufacturers.
A successful paint job is only as good as the prep you put into it – so make sure to do the work upfront, and you should get up to two seasons of protection (depending on the paint) for your hard work, along with the satisfaction of doing it yourself. Following the recommended number of coats when applying antifouling boat paint to the bottom of your boat is important. If the existing bottom paint is in good condition, you may want to just re-coat the bottom with a maintenance coat. If the existing gelcoat has cracks or blisters, you may want to apply a barrier coat before applying the bottom paint.
Follow all label directions carefully. When painting the bottom of your boat, it's important to pay attention to details such as masking around underwater metals to protect them from contact with any copper-based antifouling paint, including the bootstripe. Choosing the right type of masking tape may not seem too important in the grand scheme of things, but if you select the wrong one, you’ll spend a lot of time trying to get it off your boat. We recommend using a “long-mask” tape, such as 3M’s 2090 Scotch Blue Painter’s Tape, which is not only UV-stable but can also be left on for up to 14 days.
When painting a boat bottom, it's highly important take precautions to avoid environmental damage - both for the good of the environment and to avoid getting fined by the yard. Make sure you get instructions from your chosen yard on their local regulations and follow them religiously. We also recommend using a paint that is specifically designed for marine use and is eco-friendly, such as some of our copper-free options. Follow proper disposal guidelines for paint waste and clean up any spills or drips immediately to prevent contamination of water sources.
To paint a boat bottom, you will need the following materials: boat bottom paint, paint thinner or solvent, a paint roller or brush, a paint tray, a scraper or sandpaper to remove old paint, masking tape to protect surrounding areas, and a boat bottom primer if necessary.
We hope you've enjoyed this guide to bottom painting. Fisheries Supply sells a wide variety of antifouling paint, from brands like SeaHawk and Interlux, and Pettit. We also offer accessories, like drop cloths, paint rollers, and trays. If you have any further questions about selecting the right paint for your boat or how to properly apply a fresh coat, please don't hesitate to contact our paint experts at (800) 426-6930.