A johnboat (the term simply comes from the name; it is attested from 1905) is a flat- bottomed boat that has from one to three bench seats. Such boats are widely used in hunting and fishing tips because they are more stable than other types of boats. They may be made out of either wood or aluminum; this article will deal only with aluminum johnboats, which tend to be more lightweight and to last longer— and more specifically, with how to paint them.
Painting an aluminum flat boat often requires the cooperation of two people. The boat is very heavy, and must be placed on two sawhorses to be painted; also, you will be moving several times during the course of painting.
A great deal of preparation is necessary before the boat can be painted. First, the surface must be clear of all foreign matter, including dirt and grease; paint thinner, acetone, or grease remover, but not water, should be used for this purpose. The area in which the painting will be done should likewise be free of these things, so a garage is an ideal place. After removing the debris, sand the boat down with 80 to 100 grit paper, and use a scraping tool to remove anything that is likely to cause the paint to peal, afterwards removing the shavings with a soft bristle brush.
Then hose the boat down to remove any remaining particles, and scrub away at it using a bucket of soapy water and a hard bristle brush. Afterwards, give it a final rinsing.
The surface of the johnboat should be primed prior to painting, to improve the adherence of the paint and also help the aluminum resist corrosion. One of the best primers on the market is Duralux Aluminum Boat Paint Green, which should be put on in two coats; before this is applied, however, you should wipe the boat with white vinegar, to better the paint’s adherence even more. And you will want the layer of primer to be as thin as possible, so mix it with paint thinner at a ratio of one pint per gallon. The primer is applied with a sprayer, and must be allowed to dry before the next step can be proceeded to.
The paint should be water resistant, so use an oil- based type. The color of the paint you use is an important question, because if you will be using the boat for fishing, then you may want to use colors that blend into the surroundings, camouflaging it from your quarry (which is, really, the reason to paint the johnboat at all— the shiny metal surface is too conspicuous). Natural colors, such as dark olive green, are popular. Again, use a sprayer and apply the paint on using a sweeping motion, keeping the layers thin so they will not run or drip.
You may find that several coatings are necessary to achieve the exact color you want. An optional clear coating may also be applied.