Why is bottom paint bad

Also, fewer yards are offering DIY bottom painting. Many boaters will spend months deciding what kind of sails to buy, debating fishing tackle, or picking out electronics, yet take only 20 minutes to choose bottom paint. Written by: Zuzana Prochazka. Zuzana Prochazka is a writer and photographer who freelances for a dozen boating magazines and websites.

A USCG Ton Master, Zuzana has cruised, chartered and skippered flotillas in many parts of the world and serves as a presenter on charter destinations and topics. She contributes to Boats. Email me yachts and information. I accept YachtWorld's Terms of Use.

Home Power Sail Lifestyle Reviews. Which bottom paint is best for your yacht? The answer to this question is a bit more complex than you might imagine. All bottom paint is the same. The stuff that grows on my bottom is always the same, so one type of paint will work anywhere in the world.

Copper is or is about to be banned. In a word, yes. The quality of products has deteriorated since regulations have become more restrictive. Boaters are rushing to the newest technology. Anybody can apply bottom paint. Previous Article. Another benefit is that as it's constantly wearing away, there's no buildup of old paint, which can be a pain to remove when the time comes. But ablative paints can be less effective if your boat remains idle for extended periods of time, which denies it that self-cleaning action provided by water movement.

The flipside to this self-cleaning feature is that ablatives aren't a good choice for fast-moving boats, which would accelerate the ablation process and cause rapid paint loss. With hard bottom aka non-sloughing or hard modified epoxy paints, it's the copper biocide that gradually wears away rather than the paint itself , allowing the water to penetrate deeper and deeper into the paint until all biocide is depleted.

Hard-bottom paints form a tough, hard coating that holds up well and doesn't wear away, making them a good choice for faster boats. They can even be burnished, allowing racers to squeeze every possible bit of speed from their hull. On the downside, when the copper is depleted, the hard, tough coating remains and it can be messy and difficult to remove, particularly if multiple layers of paint have been added over the years.

Eventually this accumulated paint reaches critical mass, becoming so thick it begins to crack and peel, necessitating a complete stripping of the hull. Bottom paint is a "must have" for boats that spend most of the year in the water.

Photo: Billy Black. Hybrid or semi-hard ablative paints bridge the gap between ablative and hard paints by incorporating the benefits of both into a single product. They provide a hard, smooth surface that resists buildup yet holds up to faster speeds and repeated haul-outs without loss of protection. The type of boat you have plays a significant role in bottom-paint selection. Highspeed powerboats will want to use a hard or possibly hybrid bottom paint — ablative paints simply won't last as long at speed.

Trailerable boats are best off without bottom paint, but if that's not an option, consider a hybrid paint, which will hold up better throughout the constant launch and haul-out cycles most hard paints can't tolerate being out of the water for extended lengths of time.

Slower craft can use hard, hybrid, or ablative type paints, but the benefits of the latter two no buildup, self-cleaning, etc. For an indepth review of bottom paints and long-term test results, see Practical Sailor magazine. For boats not currently painted, application is simply a matter of following the paint manufacturer's instructions for application to a new or unpainted hull. If your boat is currently painted, you have a few considerations to address before repainting. Not all bottom paint types are compatible, so unless you plan on removing ALL of the existing bottom paint, the paint you currently have will influence your choice of new paint.

If you don't know who the manufacturer of your current paint is and plan on painting over it, at a minimum you'll need to determine whether it's a hard, semi-hard, or ablative type.

One straightforward way to do this is by rubbing the existing bottom paint with a wet rag. If the paint readily rubs off, it's most likely ablative. The general rule is that ablative paints can be applied over properly prepared hard or semi-hard paints, but hard or semi-hard paints can't be applied over ablative paints which wouldn't provide a proper adhesive surface for the hard paint. For those wanting to switch from soft to hard paint, the ablative paint would need to be removed first.

Depending on the paint and its condition i. New paint adhesion will only be as good as the paint beneath it, meaning paint in poor condition or showing signs of significant adhesion failure must be removed.

Err on the side of removing more paint rather than less, but beware: If your boat has a barrier coat applied, make sure your methodof bottom paint removal doesn't damage or remove it along with the old paint. Alternating ablative bottom paint colors first coat red, second coat blue, for example gives a visual cue as to when your paint needs renewing. As you can tell by the sheer number of bottom paints on the market, no one type or brand works best in all water, weather, and locations.

A boat moored in Maryland will require a different antifouling paint from one cruising tropical waters. One of the best sources of information on which paints work best for a particular area is your local boatyard manager. More on that later. The bottom line here is that bottom pain slowing your boat down is one of those resilient myths that keep hanging around for longer than they should because there are plenty of seemingly good reasons that extend the myth's lifespan. The main reason people choose to apply antifouling paint, the reason it was invented in the first place, is to ward off little critters and weeds and such that like to latch onto the parts of your boat that sits underwater.

Why is it you might choose not to provide mobile housing for these creatures? Some of them can weaken the structural integrity of the layer they are on and eventually, bit by bit, damage your hull. The second reason is that these creatures and plants can be far from microscopic and if you have a few thousands of seashells and a weed plantation occupying your hull, this creates considerable drag. Which reduces speed. And the need for speed is what got you here in the first place, isn't it?

At first, it seemed that antifouling paint is a good idea. But then somebody came along and started arguing that such coating slows your boat down too. Resulting in quite the opposite effect to what you were aiming for in the first place - unhindered performance. Why does it supposedly slow you down? One of the most common arguments against antifouling paint is that in the beginning, you might not notice much difference but as time goes by and you keep adding more and more bottom paint layers since the old ones lose their biocidic capabilities with time they will build up, get damaged, the coating will get rough, which creates drag.

And voila, you are back at the starting line, facing the same issue you were trying to solve originally. And as if that wasn't enough, somebody else came along and pointed out that many bottom paints aren't really smooth - especially the thick, copper-based ones, which actually tend to be quite coarse. And coarse surface must mean friction. Back to the start again. Here comes the time for the aforementioned 'back to school' moment.

Dear students, I will now attempt to challenge the bold proposition that smoother surfaces mean less friction. Daring, I know. But consider this - take two objects with very smooth, flat surfaces - say two pieces of glass or mirror. Then place them on top of each other. Because of their smoothness, they seem to have almost stuck together. The force necessary to pull them apart is quite significant. This is partially because of molecular attraction that happens when two smooth surfaces get close.

On the other hand, if you were to sandpaper these pieces of glass, making them rough, bumpy even, you would find they won't stick together as easily anymore. I know, I know, this is partially because of the lack of air in between them, but the point remains - two smooth surfaces tend to stick together.

The water surface is no exception. If you fill a glass with some water and look at the edges, you will see the liquid sort of go up the glass walls there a bit. To take this newly learned knowledge to our boatyard - if you dig around in people's experiences and opinions, you will find some say that roughing up the paint so that it is not glossy helps the speed.