What Type of Paint Should I Use on My Boat Hull?
Anything but Children's Watercolors
- A paint that's appropriate for a steel or aluminum hull, like a two-part marine epoxy paint for use in international service, is very expensive overkill if your boat is a wooden lapstrake boat that you built from scrap lumber over the course of the winter, but it would work. So would a water-based alkyd house paint. You might think not because the paint's water-based, but it lasts for 10 years or more on the exterior of a house.
The Way It Works
- If you paint your boat, the paint becomes the boat's outer skin, the barrier between your boat and the outside world. No matter what type of paint you use, the paint has a thinner -- whether it's turpentine or water -- and a binder that forms the "layer" part of a paint job. Most paints contain a pigment that adds color to the paint and additives, like those that make the paint flow more easily to prevent brush strokes in the finished work.
A Little More on Additives
- If you sail in salt water and if you leave the boat in the water most of the time, the boat's bottom is part of the marine habitat. It will become the home to pestiferous creatures like the barnacle. The barnacle is a cousin to the lobster but not one that you'd want for dinner. The barnacle glues itself to your hull, increasing drag and making you waste fuel. Certain algae also fasten themselves to your hull, with the same effects. Bottom paint, with a special additive, keeps them away.
Fresh Water and Aquatic Pests
- Waterborne pests aren't limited to salt water. Invasive species like the zebra mussel infest freshwater lakes and estuaries across the United States, destroying fish stocks and killing off the natural plant life in these aquatic ecosystems, leaving bodies of water devoid of all life. Other invasive aquatic species can foul outboard motors or, by changing the murkiness of the water along a shore line, lead to outbreaks of mosquito-borne diseases.
- Bottom paint contains copper or cuprous oxide, a chemically altered form of copper. There are two types of bottom paint that prevent aquatic growth. In one the copper dissolves out of the paint to create a chemical barrier around the hull. In the other, the paint wears away during normal boating activities, exposing the copper to create the chemical barrier.