Preparing for the boating season often includes applying bottom paint. This guide outlines the purpose of bottom paint, the different types available from TotalBoat, and how to choose and apply the right product for your needs.
What Is Bottom Paint?
Bottom paint, or antifouling paint, is formulated to prevent marine growth such as barnacles, algae, slime, and zebra mussels from adhering to a boat’s hull. This buildup can negatively impact speed, fuel efficiency, and overall performance. For boats that spend extended periods in the water—especially in saltwater or warm climates—bottom paint is essential for maintaining performance and protecting the hull.
How Bottom Paint Works
Bottom paint contains biocides (such as copper or non-metal alternatives) suspended in a paint film. These biocides are gradually released to deter marine organisms.
There are two primary types of paint films:
Ablative Paints
These paints slowly wear away over time, continuously exposing fresh biocide. This self-polishing action helps prevent buildup over multiple seasons.
Best for: Boats in regular use, seasonal use, or owners seeking lower maintenance.Hard (Modified Epoxy) Paints
These paints form a durable, smooth coating that does not wear away quickly. They are ideal for high-speed vessels and boats that are trailered frequently.
Best for: Performance boats, trailered boats, and vessels left in the water long-term.
Primer Requirements
In some cases, using a primer before applying bottom paint is necessary to ensure proper adhesion and long-term protection—especially on bare fiberglass or metal surfaces, or when switching paint types.
TotalBoat primers for bottom paint applications include:
TotalProtect Epoxy Barrier Coat Primer
Use on: Fiberglass, steel, wood
Purpose: Acts as a moisture barrier, provides adhesion when switching incompatible paints, and protects against osmosis.
Additional Info: Suitable under both bottom and topside paints.
Learn more about TotalProtectAluminum Boat Barrier Coat Epoxy Primer
Use on: Bare or prepped aluminum and galvanized metal
Purpose: Prevents corrosion and ensures strong adhesion for copper-free antifouling paints.
Additional Info: Designed for use with AlumiPaint AF.
Learn more about Aluminum Boat Barrier Coat
| Product | Type | Best For | Notes |
|---|---|---|---|
| JD Select | Water-Based Ablative | Freshwater or low-fouling saltwater | Low VOCs, easy cleanup, suitable for indoor use |
| Spartan | High-Copper Ablative | High-fouling saltwater | 45–65% copper content, long-lasting protection |
| Krypton | Copper-Free Ablative | Copper-restricted waters | Dual-biocide protection, eco-conscious choice |
| Underdog | Budget Ablative | Low to moderate fouling areas | Affordable, easy to apply, good for older hulls |
| AlumiPaint AF | Copper-Free Ablative | Aluminum hulls, pontoons, underwater metals | Will not cause galvanic corrosion, requires Aluminum Boat Etch Wash for bare aluminum |
| Outdrive AF | Copper-Free Hard Paint | Outdrives, trim tabs, running gear, underwater metals | Safe for all underwater metals, ideal over zinc chromate primers |
Surface Preparation Guidelines
To ensure optimal adhesion and performance:
Clean the surface thoroughly. Remove flaking paint or contaminants.
Sand or scuff the surface as directed in the product’s technical data sheet.
Apply the appropriate primer if painting bare fiberglass, bare aluminum, switching paint types, or preventing water intrusion.
Refer to each product’s Technical Data Sheet (TDS) for detailed preparation and application instructions. These are available on the respective product pages.
Frequently Asked Questions
Q: Can I use bottom paint on a trailered boat?
A: Yes, but hard paints are better suited than ablative paints, which may wear off on trailer bunks.
Q: How long does bottom paint last?
A: It varies. Spartan and Krypton can last multiple seasons. JD Select and Underdog are typically single-season paints.
Q: Do I need to repaint every year?
A: If the paint is worn or degraded, reapplication is needed. Some high-copper paints may last beyond one season, depending on use and conditions.
Q: What is the best paint for aluminum boats?
A: AlumiPaint AF is designed specifically for aluminum hulls and pontoons. It is copper-free and will not cause corrosion.
Q: Can I apply bottom paint myself?
A: Yes. Most TotalBoat bottom paints are DIY-friendly and can be applied by brush, roller, or spray.
Application Reminders
Once the correct paint and primer are selected and surface prep is complete:
Apply two full coats of paint.
Follow label instructions for drying times and recoat windows.
Stir paint thoroughly before and during application.
Use painter’s tape to mark the waterline.
Wear proper protective gear during application.
Additional Resources
For further assistance, please contact the TotalBoat Tech Support Team. We're here to help ensure your project is a success.