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Painting Tips
Always read and follow the manufacturer's instructions and safety precautions.
Spread plastic on the ground to collect and dispose of paint chips, sanding dust, and
drips.
Never leave bare wood exposed, it will affect your finish.
Wipe down and sand the surface free of wax coating.
Previously unpainted hulls must be cleaned with a dewaxing solvent to ensure paint
adhesion.
Optimal painting conditions are when the temperature is 50-80F and relative humidity is
below 65%.
Apply paint or varnish on a medium temperature, low humidity day for optimum drying and
no dripping.
Several thin coats are better than one thick coat.
Wear protective clothing, especially for eyes and hands.
 | Applying Bottom Paint
 | Preparation required for a successful bottom paint job begins as soon as the hull clears
the water. |
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| Clean
| Slime and growth are relatively easy to remove while the bottom is still wet, but let
the stuff dry and you will have to chisel it off. Fortunately most boat yards pressure
wash the bottom as soon as they haul the boat, and many will also knock off hard growth
with a long-handled scraper. |
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| Strip
| The adhesion of the new paint is only as good as that of the paint under it, so watch
for signs of adhesion failure. Anywhere the old paint is flaking or lifting, scrape
exposed edges with a knife or small chisel. If the paint zips off, the bottom needs to be
stripped. |
| You may also have to strip the bottom if you are changing paint type. For example, the
aggressive solvents in vinyl paints lift other types of bottom paints, so if you are
applying vinyl, any non-vinyl paint has to come off. And soft, sloughing paints are a poor
undercoat for anything other than a fresh coat of the same.
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| Using a 2" hook scraper is the stripping method least injurious to both you and the
planet, and this is often the easiest method as well. If you decide to use a chemical
stripper, be sure it is one formulated for fiberglass; regular strippers will attack the
gelcoat. |
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| Sand
| When the old paint is in good condition, in general you need only sand it, wash it, tape
the waterline, and roll on a fresh coat or two. A grinder loaded with 80-grit disks on a
foam pad can quickly prepare a hull for recoating, but it can also chew through the paint
and into the laminate in an instant. |
| If you lack experience with this powerful tool; 80-grit paper in a random orbit sander
or a finishing sander will do the same job with less risk to the hull. Do not use a belt
sander; it is designed to make things flat and that is the effect it will have on your
hull. |
| Many boat yards now prohibit normal power sanding because of the dust it generates. The
solution is a shop-vac and a random-orbit sander with a vacuum hose connection. If you
don't want to buy a new sander, slip a length of plastic hose over the dust bag mount on
your old palm sander and tape the other end into the shop-vac hose. Either rig will
capture most of the toxic dust sanding generates-but not all of it.
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| Be sure to wear a tight-fitting respirator-not a paper mask-while sanding. Also wear
earplugs to shut out the din of the sander and the vac; you'll save your hearing and find
the work much less tiring. |
| Even if you aren't stripping the bottom, it is good practice to sand away most of the
previous application. This avoids a thick build-up that will turn brittle and cause new
paint to flake. A different color first coat provides a flag that signals when you have
sanded enough. |
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| Bare Fiberglass
| A hull that has not been previously painted has mold release wax on the fiberglass that
will interfere with paint adhesion unless you remove it. Clean the hull surface thoroughly
with dewaxing solvent and plenty of clean rags before you sand; otherwise sanding drags
the wax into the scratches and it will be that much harder to remove.
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| Sand the dewaxed hull lightly with 80-grit paper before applying the first coat of
paint-the flag coat-which should be a different color from the top coat(s).
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| Stir
| Run the can in a paint shaker for at least 5 minutes to get the copper and the pigment
evenly distributed throughout the paint. Let it run for 10 or 15 minutes if it's been on
the shelf a while. In the absence of a shaker, pour half the paint into a mixing bucket so
you can mix the remaining half vigorously without sloshing paint onto the ground.
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| Keep dredging up the copper off the bottom of the can until the bottom feels clean to
the touch of your paddle. Slowly stir in what you poured off until the paint is uniform in
color and consistency. |
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| Roll
 
| Roll the paint onto the hull using a short-nap roller cover. An extension for the handle
will make painting the keel easier and keep you clear of the inevitable droplets the
roller will sling. Wear sleeves and gloves to keep the paint off your skin.
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| Fill your paint tray with paint. Dip your roller, unload it on the tray slope, and roll
it up and down on the hull, i.e. from waterline to keel. Work fast as many bottom paints
dry quickly. Each time you refill the paint tray, first stir the paint in the can to keep
the copper in suspension. |
| By the time you work all the way around the hull, many bottom paints will be dry enough
to overcoat. Check the specifications on the paint you are using. A second coat lengthens
the life of almost any bottom paint; copolymers benefit from 3 or 4 coats. No sanding or
other prep is needed between coats. Save some paint for the areas under the stand or
cradle pads. |
| Let bottom paint dry at least overnight before you put masking tape on it to paint the
bootstripe. Get hard bottom paint into the water within the time specified on the label.
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