Bottom Paint

A Primer On BOTTOM Paint

One of the advantages of owning a boat on a trailer is that the hull doesn't spend a lot of time in the water. Unlike boats kept in a marina, where hulls require bottom paint to keep from becoming a home for algae, barnacles and any number of invasive species, trailer boats are less prone to having this happen. But this doesn't mean a trailered boat isn't going to require bottom paint. It depends on the water and the amount of time the boat spends in the water.

"If the boat is launched and in the water for a few hours or up to two or three days before it is put back on the trailer, you probably do not need an antifouling paint," says Frank Winkelman, Product Development Manager for Pettit Paints. "Just wash the boat down with fresh water when it comes out. But if the boat is going to be in salt or brackish water for more than two weeks at a time, then it's a good idea to use anti-fouling paint."

If it has been more than two years since the bottom of your hull was coated with anti- fouling pant, it might be worth the time to take a good look the next time you pass by the boat and trailer. While you're at it, keep in mind the words of Jim Seidel, Assistant Marketing Manager for Interlux Paints:

"There are two questions that the boat owner should ask: Do I know what is
on the bottom already and what shape is the paint in?"

The first step is to determine what the bottom was painted with. "If you're one of those really organized people that keep a maintenance log the job is easy," says Seidel. "But if you're like me, it may take a little detective work. If you can determine what is already on the bottom and want to change the paint, check a compatibility chart- every paint company puts one out."

The next question is the easiest of the two: what is the condition of the paint currently on the hull? If the paint is cracked or peeling, it's time to face the music. One handy trick many Trailering Club Members use is to choose a different color for the first coat. When that color starts to show through, it's time to repaint.

Another trick commonly used is if the paint on the hull is unknown but a refresher coat is needed, apply a "tie coat primer." Pettit makes the Pettit 6627 Tie Coat Primer while Interlux provides Primocon YPA984. Once either of these products are used, a new coat of any kind of anti-fouling paint can be added.

Bottom Basics

There are three different kinds of anti-fouling paint: Thin Film Racing Finishes, Hard Matrix anti-fouling and Ablative anti-fouling. "It is the hard paint that must be repainted if left out of water for more than 60 days," notes Interlux's Seidel, "not the ablative types. But remember, the trailered boat guy who only keeps his boat in the water for at most a few hours or several days at a time can continue hauling and re-launching his boat painted with a hard anti-fouling on it because he never sees enough time in the water to have a fouling problem. For the guy that has his boat in the water for a few months at a time, he should be using an ablative anti fouling because it won't lose its effectiveness if left out of water.

"Anti-fouling paint uses biocides (composed of cuprous oxide-or copper) that reduces marine growth on a hull. Ablative paint will wear away as it is used, much in the way a bar of soap is reduced in size with use. Hard paint wears away over a set period of time. Because of different compounds and materials that are available in modern bottom paints, boaters have a wide variety of choices, depending on the type of hull and the kind of water the boat is going to be in.

Because sanding old anti-fouling paint has proven to be harmful to not only one's lungs, but the nearby water, most boatyards require a vacuum attachment on sanders. If you're doing the job in the backyard, these can be rented.

"It is a very good idea to be able to capture as much of the sanding dust as possible," says Pettit Paints Winkelman. "Particularly if one is sanding old anti-fouling paint. Some states and/or jurisdictions are mandating the capture of sanding debris and how to handle these residues. Many orbital or dual action sanders today come equipped with bags to catch the bulk of the dust. I have also heard of people wetting down the surface with water and using pneumatic sanders, then collecting the water run-off/debris on the ground." The vacuum attachment also improves the sanding being done because the dust is immediately removed from the hull's surface rather than being ground back in. And the sandpaper lasts longer.

You can also have the bottom professionally sandblasted but as a suggestion use someone that has experience in blasting fiberglass boats. Most boatyards will already have someone they hire and if you are doing the job at home make sure they not only do the job but also take the time and effort to clean up any blast residue. The most common blast media to use on boats right now is baking soda, but glass beads and corncobs are also being used. Stay away from coarse blast media such as sand or metal which can damage fiberglass very quickly.

If the old paint is known and in good shape: Remove old loose paint, dirt, grease, and marine growth with a power washer, brush or scraper. Wipe down with thinner/dewaxer or solvent wash recommended by your paint manufacturer. Sand with 80 grit paper. Exercise caution to avoid sanding through a barrier coat that may have been applied to prevent fiberglass blistering or damaging the gelcoat of the hull. Repeat solvent wash. Clean with the thinner recommended by your paint manufacturer. If you have to apply gel coat blister protection, follow your manufacturer's guidelines for surface and tie coat priming before you proceed with the paint application. If blister protection is not needed, you can apply paint directly to the sanded surface or the fiberglass.

If the old paint is unknown and in good shape: Clean, remove loose paint, sand (80 grit paper) and rinse with water. Apply the recommended number of coats of tie coat primer such as Interlux Primocon or Pettit 6627 to ensure optimum paint adhesion. Then simply apply the antifouling of your choice following the manufacturer's instructions. Some slippery Teflon paints such as the Interlux VC Offshore series may need to be completely removed before applying a non-compatible paint.

If the old paint is unknown and in bad shape: Remove the old coats of antifouling paint. Use specially formulated paint remover, such as Interlux Interstrip, Pettit Bio Blast or West Marine Paint Remover that is compatible with the material of your hull. You may have to apply the paint remover several times to get rid of all the layers. If you are a racer or a stickler for a super-smooth bottom, the dreaded sanding longboard may have to come out. Once the paint is stripped, check for damage to the barrier coat that provides blister protection (if there is one) and patch it where necessary. If the hull does not have an epoxy barrier coat this is a good time to consider applying this protection.

An Expert on this Hull:

"I would consider the paint on this bottom to be in very poor condition and the best way to handle this bottom is to remove everything and start over. If it were my boat I would start with a paint scraper and get off all of the paint that comes off easily. Make sure to round the corners of the scraper to avoid gouging the fiberglass. Once the easy stuff is removed use paint stripper to remove the rest. Start by sanding the paint with 60-grit sandpaper. You don't have the remove all of the paint by sanding just break the surface to make it easier for the paint stripper to penetrate the paint. Use a paint stripper that is made for fiberglass like Interlux Interstrip. Apply the paint stripper about 3 times heavier than the paint and allow it to set on the surface for a while and do the work, check after 15 minutes at 90F and 30 minutes at 50F to see if it is removing the paint. If the paint comes off easily, scrape it off and if not wait a while longer. It may take a couple of applications to remove everything. Once the paint is off, sand with 80-grit sandpaper and then wipe off the sanding residue. Once clean you can either apply the antifouling paint direct or possibly, if you choose, put on InterProtect 2000 as a barrier coat."
-Jim Seidel
Interlux Paint

Getting a Trailer Boat Off the Trailer
Don't try this alone. Have a friend with you to assist.

• Lower the trailer tongue to the ground. This elevates the transom.
  
  
• Securely set two columns of cinder blocks under the transom. Set 2"X8"X16" wooden planks between the blocks and the hull as protection. Shims may be needed to keep the hull upright if it is angled.
  
  
• Place a bottle jack under the tongue of the trailer and raise it. When the keel is off the trailer, place cinder blocks and wooden beneath the forward bulkhead just as you've done with the transom. Once this is done, lower the jack. The boat should be supported on three columns of cinder blocks and wood. Now raise the trailer jack to support the tongue and remove the bottle jack.
  
  
• Begin sanding and painting only if you are certain the boat is secure and stable.
  
  
• When the bottom paint has been applied, reverse the procedure.