Choosing the best antifouling paint for your craft

Regular upkeep in the form of applying antifouling paint to your hull is just the ticket when it comes to keeping your boat seaworthy, and in tip-top shape. Fouling is the term used to describe marine growth that can take hold on the underside of a craft without proper care, and this type of paint is specifically formulated to stop fouling in its tracks. In order to make your mastery of this particular area of upkeep easier, we're going to dig into why antifouling paint is a must. We will be covering what types of paint are available, and what you need to deduce in order to choose the best one for the task at hand.

Why is antifouling paint important?

A protective paint layer on the bottom of your boat can keep your hull clear of unwelcome residents. But why is this important? Once fouling takes hold, you can anticipate a significant impact on the performance of your craft. The maximum speed and efficiency of the vessel will be compromised, and your boat's capacity to sail upwind will be hampered. In fact, heavy marine growth can shave your speed by as much as 5 knots and add as much as a third to your fuel consumption. Historically, in the case of wooden boats, fouling also invited the chance for shipworms to bore into and damage hulls. The first examples of antifouling efforts can be found in the mid-1700s, when thin sheets of copper were nailed to the underside of seafaring vessels. Thankfully, today our antifouling resources are a little more high-tech!

What types of antifouling paints are out there?

Casting back to the 1960s and 70s, the antifouling paints that used to be in circulation developed a reputation for being nasty substances, containing ingredients like Tributyltin – a chemical since banned because of its toxic impact on marine life. Happily, contemporary antifouling paints are both safe and effective in equal measure. Two types of antifouling paint dominate the market these days, although there are other innovations around. The most popular include sloughing – otherwise known as ablative – bottom paints, which contain weak biocides. Just as ancient boats like the Cutty Sark had copper on their underside, harnessing the compounds natural biocide properties, today's ablative antifouling paints often contain copper compounds. Whatever the biocide applied, its presence serves to impede growth of barnacles, algae, and other marine organisms, without negatively impacting the broader marine environment.

Sloughing antifouling paints are designed to slowly slough off with the movement of the water, releasing and revealing a new layer of biocide. The most popular alternative to this type of paint is those which create a very smooth, slippery surface – which is very tricky for marine life to attach to. Such ultra-smooth antifouling paints may be Teflon or silicone based. Which of these two options will float your boat will depend partly on personal preference, and partly on a few other key factors.

What factors will steer your choice of antifouling paint?

Selecting the right antifouling paint is important if your efforts are to be rewarded with a nice clean hull. To make the process plain sailing, you should consider the following key factors:

  • Your hull material
    Different antifouling paints are developed for the treatment of different types of hull material. Whether your boat is glass fibre, steel, aluminium, plywood, or solid wood, be certain to confirm that your antifouling paint is compatible with the material.
  • The speed of your vessel
    Antifouling paints are rated by speed. This is important because, in the case of ablative paints, the faster the craft travels, the faster the paint will wear away. For appropriate and reliable durability, opt for a paint that is well matched to your boat's performance.
  • Frequency of use
    If your boat sees lots of action, a couple of coats of ablative paint may be a good call. In contrast, if your boat frequently sits in still water, it may not see the friction required for the paint to slough away effectively. In this case, a slick silicone-based paint may be a better choice.
  • Frequency of dry-docking
    Anticipating how often you will be able to accommodate a re-paint is always an important consideration. If you know that your dry-dock opportunities will be few and far between, an extra coat of antifouling paint could be the prudent option.
  • Previous antifouling treatments
    It is worth noting that not all antifouling paints are suitable for application over each other. Checking compatibility is a good call, and if in doubt, an antifouling primer can be used to ensure that no unexpected problems arise downstream. Some antifouling treatments are designed with the additional purpose of sealing old biocide treatments that remain underneath. Fundamentally, the perfect antifouling product awaits, whatever your specific needs.

Jimmy Green Marine stock a tried and tested selection of antifouling paints ready to assist you in keeping your craft in its prime together with some innovative ECO solutions. Explore our comprehensive selection, and follow our handy guide to estimating how much paint you'll need. If in doubt, don't hesitate to reach out to our team who will be happy to help with any antifouling related questions you may have.

Published: Dec 1, 2020