Antifouling Guide
Background
Since January 1, 2025, the ChemBiozidDV has been in force – it regulates the sale of conventional antifoulings that contain biocides. We will inform you about the new purchasing process, the correct application, and alternative antifouling solutions.
Biocidal Antifoulings: Advantages and Risks
The growth of algae, slime, and mussels on the underwater hull, also known as fouling, can significantly impair a boat's speed and fuel consumption. Biocidal antifoulings actively counteract this by releasing biocides such as copper, which prevent the settling of fouling by damaging or killing it. However, biocidal antifoulings not only combat algae and mussels on the hull but also harm other organisms in the waters. Furthermore, biocides are often difficult to degrade (persistent) and accumulate in the water and soil. In the long term, this leads to damage to ecosystems.
More Education Through Consultation
To reduce the discharge of biocides into the environment, the regulation introduces new legal requirements: Biocidal antifoulings may only be sold to private customers by our trained personnel and after a short consultation – whether in the store or in the online shop. The conversation only takes a few minutes and informs you about safe application, storage, and disposal – and about when a biocide-free alternative may be sensible.
Do you have questions about the ChemBiozidDV or would you like advice on antifouling?
We are happy to help you. You can reach our knowledgeable employees Monday to Friday from 9 am to 6 pm at the telephone number +49 40 88 90 10 - 80
First things first: choosing the right antifouling
Before purchasing antifouling, consider the following points:
- Fouling conditions in the area
Saltwater or brackish water areas often have a high fouling pressure, against which a biocidal antifouling works best. In inland and freshwater areas, a biocide-free alternative is usually sufficient. The Fouling Atlas of the German Environment Agency (Umweltbundesamt) provides an overview of the fouling conditions in German waters. - Regional regulations
There are waters where the use of biocidal antifoulings is prohibited. Inform yourself about possible restrictions with local port authorities, sailing clubs, or environmental protection associations. - Boat type & speed
Choose a product that suits your boat and your usage behavior. Biocidal antifoulings are categorized into three types:- Self-polishing antifouling
Ideal for slower boats, continuously releases biocides - Hard antifouling
Abrasion-resistant paint, suitable for fast boats and for boats that often dry out (take the ground) - Thin-film antifouling
Achieves a particularly smooth surface that minimizes friction and fouling
- Self-polishing antifouling
- Compatibility with existing coatings
Before changing products, check the compatibility between the old and new antifouling. If compatibility is unclear, a layer of barrier primer usually helps as a tie-coat. - Environmentally friendly alternatives without biocides
Biocide-free underwater paints function similarly to conventional hard or self-polishing antifoulings; instead of biocides, they contain alternative active ingredients such as hydrogel or zinc oxide to protect the surface from fouling. Silicone or epoxy resin-based underwater coatings often last several seasons. They form a smooth, water-repellent surface that is easy to clean.
Apply antifouling safely
1. Preparation
- Read application information on the label or in the product data sheet
- Only work in well-ventilated rooms or outdoors on a hard, impermeable floor
- Lay down a sheet to catch paint splatters and dust
- When sanding, enclose the underwater hull with plastic sheeting to minimize dust dispersal
2. On the job
- Wear a protective suit, gloves, safety glasses, and mask
- Perform dust-intensive hand sanding only with adequate extraction
- Keep away ignition sources (open fire, heat, hot surfaces)
- Do not eat, drink, or smoke while working
- Collect spilled quantities and dispose of them properly
- In case of skin contact, wash off quickly with warm soapy water
- In case of eye contact, rinse with water for several minutes and immediately call a doctor or the poison control center
3. Storage & disposal
- Seal opened containers airtight
- Keep out of reach of children
- Store protected from frost and direct sunlight at 5 - 25 °C
- Dispose of paint residues & empty cans properly at the recycling center; do not throw them into general waste
Self-erosion antifouling paints
Self-eroding antifoulings have a soluble resin system with active ingredients that repel or inhibit fouling. After activation in the water, the antifouling layers are controlledly degraded, ensuring a fresh and active layer with biocides is always on the surface. This results in high effectiveness during the sailing season, a smooth surface, and reduces the build-up of thick antifouling layers on the hull. For the next season, the new coat can be applied directly after a thorough cleaning and without intermediate sanding.
Content: 0.5 Liter (€0.00* / 1 Liter)
Content: 0.5 Liter (€0.00* / 1 Liter)
Hard antifouling paints
Thin-film antifouling coatings
Biocide-free underwater paints and coatings
Biocide-free underwater paints and coatings are primarily suitable for inland waters with low fouling pressure and for areas where a ban on biocidal antifoulings is in place. In other waters, such as the North and Baltic Seas, one must anticipate that fouling may adhere more readily than with biocidal antifoulings. Regular inspection of the hull during the season and cleaning with a sponge help to minimize any emerging fouling.
Content: 0.7519 Liter (€0.00* / 1 Liter)
Wie finde ich das richtige Antifouling für mein Segelrevier?
Jedes Gewässer hat seine eigenen Wasserorganismen. Je nach Temperatur, Sonneneinstrahlung, Salzgehalt, Strömung, Nährstoffgehalt (z.B. durch landwirtschaftliche Einleitung von Düngemitteln) und Wasserqualität variiert der Bewuchs, so dass nicht jedes Antifouling in jedem Revier gleich gut funktioniert.
How to find out which antifouling is suitable for your area:
- In the TOPLICHT article information, you will find indications of the area of application for which the antifouling is suitable.
- Manufacturers also sometimes provide information.
- Ask around in your cruising area, perhaps your neighbor at the dock has a secret tip.
- The Federal Environment Agency (Umweltbundesamt) has created a Fouling Atlas and provides extensive information about antifoulings, which you can find under this link: https://www.umweltbundesamt.de/themen/chemikalien/biozide/biozidprodukte/antifouling-mittel/bewuchsatlas-start
- Separate regulations and guidelines apply to some areas in Germany and abroad. Familiarize yourself with local legislation. A current list of antifoulings approved in Holland is regularly published on the "Varen doe je Samen" page.
Wieviel Antifouling brauche ich?
Zunächst müssen Sie die Gesamtoberfläche in m² Ihres Unterwasserschiffs nach folgenden Formeln berechnen - oder Sie nutzen unseren Unterwasserschiff-Oberflächenrechner weiter unten.
Bitte beachten Sie, dass die tatsächliche Fläche abweichen kann. Wir empfehlen, immer auf volle Gebindegrößen aufzurunden.
- Full-Keel Boat: Total Surface Area m² = 0.75 x Length of Waterline x (Beam + Draft)
- Fin-Keel Boat: Total Surface Area m² = 0.50 x Length of Waterline x (Beam + Draft)
- Motorboat: Total Surface Area m² = Length of Waterline x (Beam + Draft)
The required quantity in liters can be calculated using the formula: Total Surface Area m² / Coverage Rate m²/l of the paint.
Underwater Hull Surface Area Calculator
Wieviele Schichten Antifouling muss ich auftragen?
Wie erneuere ich mein Antifouling?
Wir empfehlen einen jährlichen Erneuerungsanstrich des Antifoulings, um einen ausreichenden Schutz vor Bewuchs zu gewährleisten. Wenn das Boot im Herbst aus dem Wasser kommt sollte das Unterwasserschiff so gut wie irgendmöglich, am Besten mit einem Hochdruckreiniger gereinigt werden.
Bei intakter Oberfläche:
- Die Oberfläche z. B. mit HEMPELS Pre-Clean und Frischwasser reinigen und nicht haftende Farbe entfernen (eventuell die Übergänge leicht anschleifen).
- Lassen Sie das Unterwasserschiff trocknen.
- Ein bis zwei Schichten des gleichen Antifoulings auftragen.
Bei beschädigter Oberfläche:
Die Oberfläche eventuell mit Spachtelmasse wie folgt behandeln und grundieren:
- Das Unterwasserschiff mit Schleifpapier Körnung 100 – 240 nass schleifen oder trocken schleifen mit den MIRKA Schleifscheiben und einer Absaugung.
- Das Unterwasserschiff reinigen, z. B. mit HEMPEL’s Pre-Clean und Frischwasser.
- Trocknen lassen.
- Wo erforderlich, mit geeigneten Produkten spachteln und grundieren.
- Zusätzliche Primerschichten auf geglättete, und gespachtelte Stellen auftragen, um die Spachtelmasse einzuschließen.
- Vor dem Auftragen von Primer und Antifouling das Unterwasserschiff völlig trocknen lassen.
- Ein bis zwei Schichten Antifouling auftragen.
Wenn das Unterwasserschiff neu aufgebaut werden muss:
- Das alte Antifouling komplett bis auf den Primer herunterschleifen oder das Antifouling abschaben und hinterher die Fläche glatt schleifen.
- Das Unterwasserschiff reinigen, z. B. mit HEMPEL’s Pre-Clean und Frischwasser.
- Trocknen lassen.
- Primerschichten gemäß den Produktdatenblättern auftragen.
- Ein bis zwei Schichten Antifouling auftragen.
Rolle oder Pinsel - wie trage ich Antifouling auf?
Antifouling mit der Rolle aufzutragen ist für große Flächen normalerweise die schnellste Methode. Hochwertige Schaumstoffrollen oder eine kurzfaserige Mohairrolle erschaffen eine qualitativ hochwertige Oberfläche. Pinsel eignen sich für schwierige und raue Oberflächen, sowie kleine Ausbesserungen und schlecht erreichbare Flächen.
Eine gleichmäßige Oberfläche erreichen Sie, wenn Sie auf einer nicht zu großen Fläche kreuz und quer, also sowohl horizontal, als auch vertikal arbeiten. Wenn Sie mit einem Pinsel arbeiten, sollten die letzten Pinselstriche nur noch leicht und vertikal sein. Wir empfehlen Ihnen generell die Verwendung von hochwertigen Rollen und Pinseln, um zu verhindern, dass sich die Rollen durch die Lösungsmittel zu schnell aufblähen und die Pinsel Haare verlieren.
In what weather conditions can I apply antifouling?
Always observe the manufacturer's recommendations, which you can find on the product data sheets. Generally, we recommend applying antifouling at temperatures between 10 and 25 degrees Celsius. The air humidity should not exceed 65%.
Only paint your underwater hull when it is completely dry. Due to temperature fluctuations and high humidity, condensation often forms on the underwater hull in spring; in this case, you must not apply the antifouling. Also, avoid direct sunlight on the area to be painted and do not apply the antifouling in excessively windy conditions, as the solvents will evaporate too quickly in both cases, causing the paint to dry too fast and become stringy.
I have no idea what antifouling was applied to my boat.
I would like to switch to a different antifouling product. What do I need to bear in mind?
When do I need to renew my antifouling paint?
How long an antifouling remains effective cannot be answered generally, as the effectiveness depends on several factors:
- on the type of antifouling (read the recommendations in the product data sheet),
- on the applied film thickness,
- on the vessel's speed,
- on the water temperature,
- on the microorganisms present in the water,
- on the general condition of the underwater hull (does the paint adhere, is it nicely smooth).
To maintain optimal effectiveness, a new layer of antifouling should usually be applied annually. It may also be sufficient just to touch up the antifouling, as the antifouling is typically consumed fastest at the waterline, rudder, and keel.
Is a primer necessary or not?
TOPLICHT tip for self-eroding antifouling:
When completely recoating the underwater hull, it is advisable, after sealing with an epoxy primer (e.g., HEMPEL Light Primer), to first apply one coat of hard antifouling, and only then apply 2 coats of self-polishing antifouling in a different color. This can save work and money, because it is only necessary to apply new self-eroding antifouling when the color of the bottom layer becomes visible.
