you've finished all the physical structure of your boat, it's time to give
it some personality with a lick of paint. although this may appear to be
the only effect painting your barge has, it performs the vital task of preventing
rust, both above and below the waterline.
for the steel of your barge to rust, it must be in contact with both Oxygen
and Water. By painting the outside of the shell, you prevent both of these
from being able to reach the surface for 2-3 years, so regular re-painting
is a necessity. In the case of the boats hull, it is important that you
thoroughly coat it with "blacking" (often a bitumen or coal-tar
based paint). Two or three coats of this is normally applied directly onto
the steel of the hull. It is highly recommended that a six inch strip of
the hull along the waterline is given an extra few coats, as this is the
area most exposed to the elements that contribute to rusting.
the waterline you get a little more creative freedom, but it is still important
that you adhere to certain rules so that your paintwork lasts as long as
possible. You should apply three layers of paint above your blacking. The
Primer, Undercoat and Topcoat. The primer is applied directly to the steel,
and is the protective layer which prevents air and water mixing with the
steel. This coat should also be applied to the interior of the boat, making
sure that areas such as the weed hatch and lockers are fully coated too.
Items such as the rudder should also be primed, but ensure to do this while
they are off the boat so that the entire surface is covered.
The Undercoat is applied next, the main purpose of which is to build up
the thickness of the coat and fill out any imperfections in the steel work
or primer. The undercoat is often a much thicker layer for this reason,
and also flows out more easily to give a flat surface. You should apply
at least 2 coats at this stage. The undercoat should be sanded smooth using
a random orbital sander, rather than a standard one which will leave permanent
marks that will show through the top coat.
the top coat is applied to give the glossy finish you expect from a narrow
boat. It gives the tough, abrasion resistant finish, and in many cases protects
itself from being faded by the sun and constant exposure to the atmosphere.