Painting bottom of boat

[Lightning Rod]

Can the bottom of the boat be painted? I know they have bottom paint, but I am looking at having the bottom painted black to match the boat. Will it last?

[Ewok]

It depends on how you use your boat, do you plan to leave it in the water? That is why most use it. There are 2 types, ablative and a harder enamel type. The enamel will last longer but it will loose it's anti-gunk properties over time and you may not care. The albative type wears off over time but that let's you know when your gunk protection is done and when to re-apply. You can get the paint color matched to most colors and it's better to let a boat yard or ship yard apply it. They will take your boat off the trailer and put it up on special jacks to paint the entire bottom, kinda hard to do on your trailer.

[Lightning Rod]

It depends on how you use your boat, do you plan to leave it in the water? That is why most use it. There are 2 types, ablative and a harder enamel type. The enamel will last longer but it will loose it's anti-gunk properties over time and you may not care. The albative type wears off over time but that let's you know when your gunk protection is done and when to re-apply. You can get the paint color matched to most colors and it's better to let a boat yard or ship yard apply it. They will take your boat off the trailer and put it up on special jacks to paint the entire bottom, kinda hard to do on your trailer.

Thanks Ewok,
Don't those paints in general look like crap? Looking for mora of a factory smooth finish, can they accomplish that. It is in the water for the season so a bottom paint will be needed.

[The friend Ship]

just curious, how much is it to re-paint a boat?

[Ewok]

Thanks Ewok,
Don't those paints in general look like crap? Looking for mora of a factory smooth finish, can they accomplish that. It is in the water for the season so a bottom paint will be needed.

I have seen smooth paints and the bumpy bottoms your talking about. I believe the more bumpy paint is the albative type. If you are leaving your boat in the water for the summer, you should use bottom paint. Some good websites about bottom paint and gelcoat blisters make NO claims that bottom paint will help prevent blisters but I think it makes sense that bottom paint will help prevent gelcoat blisters by adding a layer of protection from the water to the resin.

If you search around you can find clear bottom paint and spend a little on getting it tinted to match your boat. I would check with a local boat yard that does bottom paint, tell them where you keep your boat and ask what they recommend.

Here is a little bit of info from marinepainting.net.


Ablative & Soluble Copolymer Bottom Paints

The older ablative paints were made to wear away through friction as the boat moved through the water, and some of these paints are still available today, such as Interlux Bottomkote ACT and XXX. The problem with these paints is that water wears the paint away much more quickly in areas of high friction, such as the leading edge of the keel and waterline, leaving those areas exposed while there is still plenty of good paint on the rest of the hull.

Modern ablative paints with water soluble or self-polishing copolymers dissolve at a predictable rate, and are not as susceptible to friction wear so tend to wear more evenly and last longer. Paints such as Pettit Ultima and Interlux Micron 66, Micron Extra and Micron CSC, as well as Awlgrip Awlstar, Seahawk Cukote, Super Shipbottom, paints by SeaJet and others fall into this category of more advanced ablative type paints. Pettit's Vivid is a special case, and has characteristics of both ablative and hard paints. The copper thiocyanate biocide and zinc slime-inducers do dissolve away like an ablative bottom paint, but they leave behind the Vivid paint, as happens with a vinyl or epoxy antifouling coating.

Hard Bottom Paints

Hard bottom paints like Pettit Trinidad SR and Unepoxy, Interlux Ultra and Fiberglass Bottomkote, Seahawk Sharkskin and Tropikote and others are durable and can be made very smooth. It is possible to achieve and maintain a smoother finish with these bottom paints than with most ablative types and the paint is long-lasting.

The downsides of the hard paints are that many lose effectiveness when out of the water, and the paint will build up over time if not sanded down each time the boat is bottom painted. Also, hard paints are at their most effective immediately after launching, and are less toxic to marine growth over time as the poisons within leach out. That means that after a year or so, a hard bottom is likely to need more scrubbing than an ablative bottom, which will still just need a light wipe to expose fresh paint with copper biocide.

High Performance Bottom Paints

Racing sailboats and powerboats frequently use special bottom paints with Teflon to minimize hull friction. Common choices for fresh water use are Interlux VC 17m and Pettit SR-21, while salt water racers use Interlux VC Offshore or Baltoplate. These paints are generally incompatible with other paints, so if some crazy racer has put VC 17 on a hull you bought, you will have to remove it before applying a different type of bottom paint.

The racing paints must be applied correctly in thin layers, then wet sanded with increasingly fine sandpaper, then burnished with cloth or newspaper until it shines to produce their maximum performance finish. Vivid is also used by racers, but the zinc in it produces a smooth coating of slime. It just needs any growth wiped off. High tech racing teams also commonly use Durepoxy, a biocidal epoxy bottom paint for high performance boats.

Special Purpose Bottom Paints

There are also a few special purpose or unique antifouling paints, such as EP 2000 by ePaints. This copper free paint uses different biocides and generates hydrogen peroxide around the hull to discourage marine growth. It is safe for aluminum, as is Interlux's Trilux 33 and Pettit's Alumacoat SR. There are also biocide free super-slick paints that are simply too slippery for marine growth, and manufacturers are working on spray-on glass surfaces. Inflatable boat antifouling paint is specially formulated to stick to hypalon rubber and flex with it without peeling off.

Choosing the Right Bottom Paint

There is a bottom paint for every purpose and the right one for your use depends on laws in your area, the previously applied bottom paint or hull surface material of your boat, how much work you are willing to do, how fast you want to go, how much you want to spend, and how long you want it to last, among other factors. It's a very personal choice, a little like choosing the boat itself, but slightly less permanent and expensive.

Most of those questions can only be answered by the boat owner, but the bottom paint compatibility question can be easily solved by examining the manufacturers' compatibility charts. These charts show which paints can be used over various other paints, or on bare fiberglass, wood, or metal hulls, and the type of surface preparation that is recommended. Some require only a light sanding and solvent wipe down, while others must be completely stripped before the new paint can be applied.