Paint Manual - Dove-Medows Marine Coatings Ltd

Antifoulings and bottom coats
Fouling not only makes a boat look unsightly, it can also
foul propellers and outdrives, block engine water inlets and
outlets, slow down the boat speed, increase fuel costs and
ultimately damage the hull substrate/surface.
Painting a boat’s underwater area:
• protects its substrate/surface
• avoids undue hull roughness.
(Roughness increases resistance
through the water, causing lower
speeds and consuming more fuel.)
Fouling varies widely depending
on temperature, salinity and water
quality. Differences in levels and
types can be dramatic, even on
boats moored in what seems to be
the same environment, as fouling
conditions are affected by sunlight/
shade, temperature and flow of water,
pollution levels and water inflows.
Fouling grows faster in sunlight, so is
first seen on the waterline and rudder.
Water surface dirt and pollution can
adversely affect the antifouling.
Key advice:
Put extra layers on the rudder and
waterline where more aggressive water
flow takes place.
How antifouling works
Antifouling paints release bioactive
ingredients. The bioactive materials
used today are mainly cuprous oxide
and booster organic biocides. They’re
water-soluble and, when released,
lethal to fouling organisms.
Different types of antifouling paint
release biocides/toxicants in different
ways. There are three main types:
• Self Polishing/Erodible
• Hard
• Traditional/Soft.
These are explained on the next page.
Choosing the right product
You should consider:
• boat type
• sailing pattern & speed
• geographic location and
characteristics of the mooring
• any existing coating
• environmental and legislative
issues in the area where you
apply the product and sail.
55
Antifoulings and bottom coats