Hull Refinishing

Mark Angliss

It is quite possible to achieve very respectable hull finishes in a home shop. Gel coat finishes are not suggested for this environment due to the difficulty of working with the materials and equipment. Paints are what will be addressed in this article. Paint may be applied either by roller or with conventional spray equipment. The application technique will determine what type of paint is required. If you are limited to roller application, your paint selection is limited to the two-part marine epoxy finishes. Automotive type finishes CANNOT be applied by a roller. You will find marine epoxies come in a rather narrow range of colors. It is possible to mix epoxy colors to achieve different shades. However, if you do this, bear in mind that you must mix the "color" portion of the paint for the entire job all at the same time. Also, if you ever need to make a repair, the color is going to be tough to match. If you opt for a custom color, buy more paint than what you need. (4 quarts color & hardener for a 505) Mix the colored components of the paint (no hardener!!!) until you achieve the desired shade. Epoxy paints don’t change very much after drying like latex house paint does. However, the addition of hardener will probably lighten the shade as the pigments are diluted. To check the color, mix a small sample of the proposed colored resin with the correct amount of hardener. Compare the colors in both the wet "pot" stage and after the paint has been applied to a scrap to make a color chip example. Adjust by adding a small amount of the darker color. You may (and should) mix the blended paint with hardener in small batches to prove the color match.. Non-hardener color blended resins will keep for several years for possible future repairs if sealed in very full containers. Partially full containers will be unusable in less than a year. Many paint or hardware stores can provide you with small unused paint cans. Glass jars will work, but need to be protected from light. Plastic containers are not recommended as they "out-gas" plasticizer and mold release agents that contaminate the paint. If you opt to roll your finish, consult your paint supplier for the best roller covers to use for the paint & primer you purchase.

If you opt to spray, you may use either the marine or certain automotive finishes. (see Construction and Materials article.) Automotive finishes offer a very large range of color selection and are very easy to match if future repairs are required. From a life perspective, the marine epoxies are a bit tougher than automotive types. Regardless of paint selection, the correct primer must first be applied to a properly prepared hull. Consult your supplier for the correct primer for your hull material type & paint selection.

For any paint job, the end results will be determined by the environment that the paint is applied and allowed to cure in. Wet paint is a remarkable "dust magnet" so care needs to be taken to keep dust to an absolute minimum. Sprayed paint in it’s airborne "fog" state can also get into and stick to seemingly hidden surfaces. Therefore, proper masking is required. You will find it will take longer to properly prep for paint application than it does to do the actual painting. Plan this into your schedule. Don’t rush prep!!

Before painting, clean the work area well. Get rid of dust/debris piles, dusty rags, tools etc. Your "paint booth" needs to be draft-free and warm (65-85 F) during the entire application and drying process. If working on a concrete floor, wash it well. If working on a dirt, asphalt or rough wood, lay down a clean cheap plastic drop cloth as a "floor". Duct tape or staple cheap polyethelene drop cloths to form walls of the "paint booth". The walls are especially important when spraying to keep other items in the shop or garage from being "fog coated" with paint. If you are going to spray, secure the bottom of the "walls" with tape or weights to keep them fixed in place. (air motion from spraying will "suck-in" the walls like an annoying shower curtain)

Now do the final boat prep before applying the primer coat. The techniques are the same for applying the finish coat, however primer is less critical of appearance for over-spray and blushing. With primer, just be sure that all areas are covered. Wipe the hull with a solvent soaked rag to remove the majority of dust & contamination. Perfection is not required yet. Apply REAL masking tape to all edges that need protection. (real masking tape has kind of "waxy" in feel, heavy and often blue colored. See any good paint store) Use masking paper as a "skirt" around the hull or to protect parts of the hull that are not to be painted. Don’t use newspaper! Paint drips soak into the paper and cause a mess. Finally, lay down some old bed sheets or purchase cheap cotton bulk cloth from a fabric store to put on the floor of the walking/moving area. Wet down the cloth with water to attract, trap and absorb dust. If the work space is heated, TURN OFF THE HEAT AND EXTINGUISH ALL PILOT LIGHTS!!! Don’t re-light pilots until after the fog has cleared if you spray. Give the hull a final wipe with a solvent dampened (not soaked) rag or a standard tack rag. You are now ready to paint.

If you have never sprayed paint before or are "rusty", be sure to practice before attempting to paint your boat. For most work with a conventional syphon gun, set the pressure to between 40 and 50 psi. Hold the gun still and pull the trigger for ½ a second at a distance of 12" to 14" from a piece of scrap plywood or masonite. Adjust the feed rate and fan spray to apply a wet (not runny) "oval" that has 1"- 2" of thin "over spray" surrounding the wet pattern. When spraying, keep your wrist LOCKED to your forearm and move the gun parallel to the surface. Release the trigger BEFORE you stop moving or change directions. Begin at the keel at the transom and work outward and forward on one side at a time applying a uniform wet coat. Don’t try to cover everything at once, it will require 3 coats. Be careful the air hose does not get dragged through the wet paint! Toss the hose over your shoulder or tie it to your belt. It is important that the paint "levels" to a smooth gloss upon application and does not appear to be dry-dull (not enough paint feed) or have a "textured" look. (too much air pressure) If the paint begins to run, you are too close, not moving fast enough, not releasing the trigger before you stop or change directions or have too much paint feed. If the gun spits or drips, you have too little air pressure or the nozzle needs to be cleaned. You need to apply the second and third coats when the previous coat is no longer "wet", mildly tacky and not yet dry. Depending on your skill & speed, you may need to apply all three coats to one side of the boat before beginning the other. "Boo-boos" CANNOT be fixed by applying more paint! You MUST wait for the paint to dry, re-sand and re-spray a touch-up.. It is better to leave a run alone than try to wipe it off. It will sand-out and can be touched-up. Primer goofs are especially better left alone. Many will "magically" disappear or become less serious after the primer has dried. Primer needs to be sanded regardless so don’t sweat a few blotches.

Allow the primer to dry at least 12 hours or the recommended minimum time before messing with it. Using a hand held sanding block (NOT a machine) CAREFULLY flatten any runs drips or blemishes with 220 grit dry paper. Cut a sheet of 320 grit wet-or-dry paper in half, then fold it in thirds. Keep a bucket of warm water near you as you wet sand the entire primer surface. When the paper begins to "drag" drown it in the water bucket. When you wet sand you should be able to develop "feel" pretty quick for what is happening. When you first start, it will feel more like dry sanding with a gritty cutting sensation. As you work, you will feel more of a slick almost suction like sensation. At this point the area is probably finished. (for primer that is) As you work, wipe the completed areas with a sponge or wet rag to remove excess "haze" before it dries. After you have completed sanding, wipe the hull down using clean rags with fresh clean warm water. For each gallon of water, add 1 drop, yes ONLY 1 drop of liquid dish washing detergent. When the hull has dried, areas that you missed sanding will be quite visible. Touch them up, wash the hull again and you are ready for the color finish coats. Set up your work area and wipe the hull just before painting with a tack rag or a solvent dampened rag.

Two or three color paint jobs are best performed by over-lapping into the adjoining color area. Don’t try to make the colors "meet" at the edge. For a two-color scheme, paint the bottom first and over-spray into the hull side area about an inch. After the paint has dried, wet-sand the edge of the paint to remove the "ridge" and blend into the hull with 320 grit paper. Mask the dividing line edge and cover the painted bottom to spray the upper hull color. For a different colored boot stripe, paint the whole hull, mask & paint the stripe. For a three-color job, shoot the top & bottom overlapping an inch or so into the boot stripe area. Wet-sand the ridges to blend, mask & paint the boot stripe.

To mask boot stripes or water lines, you can "eye-ball" the placement of the masking tape by measuring from the keel to both sides and marking symmetrical distances. Another method is projecting a builder’s level laser beam on the hull and applying the tape to the illuminated area. Another trick is with a 35mm slide projector. Knock an unwanted slide out of the cardboard frame. Stretch a hair from your head (or someone else’s) across the slide and scotch tape it in place. This will project a "shadow line" on the hull from stem to stern that the masking tape can be referenced to.

The last section addresses cutting & buffing for the final finish.