Why You Shouldn’t Use Pressure-Treated Wood for Boat Trailer Bunks

When it comes time to replace your trailer bunks, the type of lumber you choose makes a big difference. While pressure-treated wood is often used in outdoor projects because of its resistance to insects and rot, it’s a poor choice for boat trailer bunks. Here’s why:

1. Accelerated Corrosion
   Pressure-treated lumber is saturated with copper-based chemicals. In a marine environment, those chemicals react with the galvanized steel or aluminum used in your trailer, speeding up corrosion of bunk brackets, bolts, and even the trailer frame itself.
2. Hardware Damage
   Standard fasteners and brackets deteriorate quickly when in contact with treated wood. Unless you’re using costly stainless or specially coated hardware, your bunk supports will fail much sooner than expected.
3. Boat Hull Wear
   Treated lumber is rougher than untreated wood. Once wrapped in carpet, the chemicals and splinters can break down the carpet and create abrasive spots. Over time, that can scratch or gouge your boat’s gelcoat or hull.
4. Moisture Retention
   Even though it’s treated, this wood still absorbs water. Wrapped in carpet and submerged during loading and unloading, it tends to stay damp. This creates the perfect environment for rot from the inside out.

The Better Alternative
Untreated pine or fir remains the industry standard for trailer bunks. When properly sealed and wrapped in marine-grade bunk carpet, this wood offers the right balance of durability, protection for your boat’s hull, and compatibility with your trailer hardware.