Every current or prospective boat owner has undoubtedly at some point wondered if boats need bottom paint. The idea of having to paint the bottom of my boat seemed a bit strange to me, so I researched in a bid to understand all I could find about the complex world of boats and bottom paint.
So do boats need bottom paint? Boats need bottom paint to prevent organisms like barnacles or algae slime, from growing and attaching themselves to the hull when the boat is kept in the water for extended periods. These organisms can slow a vessel down, mess with their performance and even reduce durability.
Boats that spend more time on the water are likely to need bottom paint in order to maintain their sturdiness, but if your boat doesn’t stay on the water for long periods of time, you may not need to paint its bottom, however, don’t be too hasty in making any conclusive decisions yet as there’s more involved than just the length of time boats spend on the water in effect to bottom painting.
Bottom paint is, however, not needed in all circumstances and in some instances, a boat might be just fine without it. Choosing the right type of bottom paint is also important as each type is better for a different circumstance, and it can be tough to choose. There is also the question of how often bottom paint needs to be applied.
Deciding if you need bottom paint
Usually, in the discussion of suitable bottom paints for boats, the type of paint referred to is anti-fouling paint. Anti-fouling paint is used to prevent water-based organisms from fouling the hull of the boats. This is when they attach themselves to the hull, usually affecting the overall hydrodynamic performance of the vessel.
Anti-fouling paint contains a biocide that is responsible for keeping the organisms at bay. Currently, the most common biocide used in anti-fouling paint is copper, which has replaced tin as the preferred biocide in anti-fouling paint. Generally, the higher the amount of copper in a paint, the better it works, although it is likely to cost more as well. Modern anti-fouling paints are, however, increasingly trying new biocides and using little to no copper due to potential environmental dangers of copper.
All types of boats need anti-fouling paint. However, wooden boats may need it more as they usually encounter more damage. The organisms do not just attach themselves to wooden boats they eat into their hulls. Hence they do not only affect the performance of wooden boats but their durability as well.
Your boat will need bottom paint if it spends a lot of time in the water, regardless of whether that water is freshwater or saltwater. While freshwater might be free of the typical problem organisms like barnacles, it is susceptible to plant and algae slime, which can also affect the performance of the boat.
There are instances in which bottom paint is not needed and can be overlooked. They include :
- Keeping the boat outside of water regularly in a lift which ensures the boat remains dry and is therefore not prone to fouling attacks from organisms.
- Using the boat exclusively in freshwater then hosing it off immediately after which it is then stored in a dry place out of the water after use.
How To Make The Right Bottom Paint Choice
Choosing the most suitable bottom paint for your boat can be complicated since it involves taking chemistry, environmental challenges, and your local water conditions, among others into consideration. Many factors, such as how different speed boats travel and whether or not they are used regularly should be taken into account as well. Bottom paints are classified into three categories. They are:
- Ablative
- Hard
- Hybrid
Ablatives wear off. They erode during movement on the water delivering biocides and resulting in an unstable environment for marine organisms to cling to. Their biocide delivery is more efficient than in hard paints. Ablative paints come in several varieties, but they all perform the same function of wearing away through chemical reactions or physically through the passage of water over the surface of the bottom of the boat. This paint type works best in high growth waters and lasts longer when the coat of paint applied is thicker.
Hard paints or contact leaching paints are sturdy and hard to wash off bottom paints that are heavy laden with biocides that leach out of the paint to kill and prevent growth on the bottom of your boat. However, once the paint is stripped of all biocides, it leaves behind the hard paint which remains intact but has no more anti-fouling effects. Hard paints are resistant to abrasion and friction but can be sanded to make the boat move faster and reduce drag.
Hybrid anti-fouling paints are a newer addition to the anti-fouling paint family that combines the better qualities of both hard and ablative bottom paints. They have a more liquid and slippery feel which dry into a thin liquid film that is quite slippery to the marine fouling organisms, so they cant attach themselves to its surface. It is an excellent alternative to the more traditionally known ablative and hard paints.
Application of Bottom Paint
Painting your boat with anti-fouling paint is a task most boat owners do not look forward to. All the same, choosing and applying anti-fouling paint is necessary for your boat’s utmost performance. The application of anti-fouling paint should be done in the best conditions to give it long-lasting effects. The items needed for the application include:
- small to a medium-sized roller with an extension handle
- face masks
- overalls
- goggles for eye protection
- gloves to prevent direct body contact with the paint.
Before you begin applying, the bottom should be primed by scraping and washing to clear away any existing fouling. It helps if the surface is as smooth as possible to prevent a buildup of paint layers. Professional application by spraying is also an option, but I would not recommend it without prevention measures to avoid breathing in harmful and dangerous fumes and particles. Protective headgear also will not be amiss as rubbing your head against the underside hull is a distinct possibility with dangerous effects.
Bottom Paint Longevity
Paint on the bottom of your boat gradually builds up year after year, and eventually, the thickness will get to a point where it has to be peeled back to the bare hull. Therefore, it is recommended to do that four to five years where self eroding anti-fouling paints are concerned. Hard anti-fouling paints, on the other hand, can last for up to two years or even longer if applied accordingly and are of good quality. You will know when it is time to take off your old paint by the following signs.
- Large holes in old paint layers.
- Water blisters under the paint.
- Peeling of paint in flakes leaving ragged edges.
- If the surface of the bottom just looks bad in general
Related Questions
Does bottom paint prevent saltwater corrosion in aluminum? There are special kinds of paints to prevent saltwater corrosion in aluminum boats and anti-fouling paints only prevent fouling.
What’s in your anti-fouling paint? Anti-fouling paints are made from a complex formula of gum rosin, plasticizers, oxide, acrylic, thixotropic, zinc oxide, preventolA4S, solvent xylene, and extender pigments, among others. They vary across the types.