Latest News

DIY Antifoul Checklist

DIY Antifoul Checklist

It is time to do the annual slipping. So what are the key things we should be looking for to ensure all the proper maintenance is done?

Antifouling is designed to keep growth off your boat. The signal to book the slip will be the presence of hard shell and weed starting to build up. This indicates that the biocides in the antifouling are exhausted or the product has worn back to previously used coats.

Once you have decided to slip your vessel, make sure of a number of things with this quick checklist on both antifouling and other components:

• The hull must be thoroughly washed with fresh water at about 3000-5000 psi.

• All weed, shell, slime, and the soft soapy layer of antifouling must be removed back to a clean, hard surface.

• Check for any excessive thickness of the antifouling from years of build up after many coats. This will mostly be around the waterline.

• Check for any peeling or cracking back to old, previous coats. If this is excessive, it may be time to think about removing all the old antifouling back to epoxy primer, and then re-applying. Putting new antifouling over old delaminating coats is ineffective and the new paint will just fall off with the old. You can do this yourself with tungsten blade scrapers. It is hard work and will take a number of days depending on the size of your boat. The alternative is to have the paint removed with some form of abrasive blast. Check with the yard to see what they can offer. You may still be able to do the re-application of the paint system yourself after all the old coats are removed.

• Always undertake a hull inspection. Look for any delamination cracks, pitting, holes, soft spots, and any osmosis. If you encounter any of these elements you should consult a qualified shipwright for their opinion.

• If the antifouling is OK and can be over coated, ensure the bottom has been wet-rubbed with 80-grit sand paper or a brown doodlebug pad, washed again, and dried before applying new paint.

• When checking over your hull, look for any areas where the epoxy is exposed, bare hull or fibreglass as these areas will need to be spot-primed with a good quality epoxy primer or tie coat prior to the application of your antifouling paint.

• Antifoul selection: Make sure you talk to the professionals about what antifouling paint best suits your vessel, whether it is fibreglass or aluminium. This is extremely important. Remember we all have different vessels, live in different locations, and use vessels differently.

• Two coats of antifouling should be applied to get the best performance. Have it applied by airless spray if you can, as this results in a very smooth finish, aiding the antifouling performance. For powerboat owners, this will reduce fuel usage.

• It is important to know what products are being put on your vessel. It is OK to change your antifouling product from the previous applied products. However, it is important to remember the golden rule: you can put soft ablating antifouling over hard ablating antifouling, but not the other way around.

• If you are not sure, it is recommended to apply a “tie coat” in the product brand of your new antifouling. This intermediate “tie coat” is a single pack product designed to seal the old antifouling system and give the new antifoul system a good foundation.

• If you are having your application applied by a professional, then ensure that the correct amount of antifouling is being applied,]. Remember to apply two (2) coats, not one (1) coat. Always check that the professional is experienced, and always ask what type of warranty they provide.

• Rolling on your antifouling produces a rougher surface profile where the slime will attach. Ensure that your roller is not leaving excess built-up streaks at the end of your roller sleeve as this will cause an uneven substrate, which affects self-polishing and ablating properties while your vessel is in motion.

• To get the best life, the right amount of antifouling is critical. Antifoulings are made of soluble resin and wear away over time, so it makes sense not to apply too thinly. If you are not sure how much to use, calculate the underwater hull area and divide by 6sq metres per litre per coat to get an average. This isn’t perfect but it will get you close enough. A simple formula is LWL x (B+D) Load waterline x (beam + draft).

• While your vessel is out of the water, don’t forget to check your sacrificial anodes and see if they need to be replaced. Check your propeller, shafts and rudders. After a thorough clean, ensure these surfaces are well keyed/ sanded and free of dust, grease and contaminates. They can be epoxy-primed and painted with a hard ablating antifoul or alternatively painted in the silicone-based product designed for these components. Always check with the professionals. Also, check your transducer and speed pilots, and clean if necessary. Check your current flow earth blocks as well. Do not antifoul your earth block. (Some residual earth blocks are designed to release current flow.)

• Most antifoulings can be launched back in the water in about four (4) hours. But overnight drying is always better. Try not to rush things. It is a good idea to check your product data sheet regarding the launch times back into the water.

• While your boat is on the hardstand, it is the perfect opportunity to have your vessel cleaned and polished. With gelcoat being porous, it is important to remove all fall-out and chalkiness from the vessel by wet sanding with a 1500g, 2000g or 3000g soft pad, prior to polishing. This will ensure that you are polishing a flat substrate in order to obtain a better outcome that lasts longer.

• When your vessel is lifted to go back into the water, don’t forget to touch up your antifouling where the stands and cradle points were located. This is where your new antifoul job can rapidly deteriorate with weed and crustaceans attaching very quickly.

• Once back in the water, a little maintenance over the next 12 months will help extend the life of the antifouling. These coatings will keep shell and weed off. However, slime and mud can settle on the hull. If you see this, give it a gentle wipe off with a sponge or a cloth. Don’t be too aggressive with this as you may scrub the antifouling off and reduce its life expectancy. If you leave it to build up, it may get sufficiently thick to stop the antifouling from working properly.



IN SUMMARY, the important things to remember are:

• Clean the hull thoroughly.

• Undertake an inspection of hull and components.

• Proper preparation is vital.

• Ensure you get the right antifoul for your vessel.

• Apply enough paint.

• Do your in-water maintenance.

• Have fun boating.

No Comments so far

Jump into a conversation

No Comments Yet!

You can be the one to start a conversation.

Your data will be safe!Your e-mail address will not be published. Also other data will not be shared with third person.