This spring, before we put our boat in the water, we painted the bottom and mixed cayenne pepper into the paint. Any little organisms wanting to hang on the bottom of our boat should get quite a zing. Hull coatings have relied on some pretty toxic stuff to keep plants and animals from making themselves at home on the bottoms of our boats. More environmentally sound solutions are now available, and cayenne pepper is one of them.

Capsicum frutescens, chili pepper. Did you ever think of using it on your hull to keep critters from hanging on? Photo by Eric Hunt

The argument seems to break down into two categories: hard bottom paint vs. ablative bottom paint. There are plenty of options in both. Ablative bottom paints are designed so that the top layer falls away perpetually uncovering fresh anti-fouling yet detrimental ingredients.

Research has produced hard coatings which have less toxicity and longer lasting effects. These silicone, Teflon, and other “non-fouling” paints rely on a slick surface to prevent the little buggers from growing rather than on toxic components to kill growth.

There are a few main approaches to keeping your boat free of bottom growth.

  1. Store her out of the water. The best method to keeping the growth off your hull is to haul your boat out and clean her each time you’re done using her. We all learned when we were young to pack our toys away when we were done playing with them and clean up after ourselves. However, that’s not an option in many cases.
  2. Ablative or “sloughing” paints are moderately soluble, so the top layer falls away constantly exposing fresh paint and fresh harmful ingredients.
  3. Hard antifouling or “contact leaching” paints act through the biocides held in the pores of the surface and released slowly. This type of bottom coating has longer acting antifouling qualities and minimal leaching or sloughing of toxic metals.
  4. Teflon/silicone (not silicon) coatings act by creating a smooth, nonporous surface where growth can’t get a hold of to attach.
  5. SealCoat system, a biocide-free coating, uses an epoxy resin to seal the surface. The finishing layer consists of synthetic micro-fibers that protrude slightly from the epoxy layers, thus resembling the velvet-like skin of the seal. SealCoat works mechanically due to the movement of the fibers in the water, even when the boat remains idle.

By Elizabeth Kelch