Antifouling - 02/2020
YACHT SERVICE LAKE MAGGIORE
ANTIFOULING LAKE MAGGIORE
YACHT SERVICE - Antifouling Lake Maggiore.
Boat maintenance and care: The antifouling treatment.
YACHT SERVICE - Antifouling Lake Maggiore
advises on the different types of antifouling paint and the correct application of antifouling:
Why, when and how should a yacht receive an antifouling paint?
At the latest when a yacht is drained at the end of the season and various types of fouling have settled on the hull, the answer to the question "what for" is revealed.
The growth of plant and animal organisms on the hull is natural and depends in particular on the water quality of the area being sailed on.
Once the underwater hull is densely overgrown, several problems arise. Propulsion is slowed down and increased fuel consumption is the result. The manoeuvrability of the vessel also decreases, which can become a safety problem. Animal organisms in particular can compromise the populated surface through their growth and thus cause consequential damage. Examples are osmosis on GRP hulls and rot on wooden ships.
An antifouling paint applied as a precautionary measure counteracts the growth of vegetation on the underwater hull by toxins, so-called biocides. Until a few years ago, these biocides consisted of highly toxic substances, which obviously prevented any fouling. Today, the substances used must comply with strict standards to avoid unnecessary environmental pollution.
Why, when and how should a yacht receive an antifouling paint?
At the latest when a yacht is drained at the end of the season and various types of fouling have settled on the hull, the answer to the question "what for" is revealed.
The growth of plant and animal organisms on the hull is natural and depends in particular on the water quality of the area being sailed on.
Once the underwater hull is densely overgrown, several problems arise. Propulsion is slowed down and increased fuel consumption is the result. The manoeuvrability of the vessel also decreases, which can become a safety problem. Animal organisms in particular can compromise the populated surface through their growth and thus cause consequential damage. Examples are osmosis on GRP hulls and rot on wooden ships.
An antifouling paint applied as a precautionary measure counteracts the growth of vegetation on the underwater hull by toxins, so-called biocides. Until a few years ago, these biocides consisted of highly toxic substances, which obviously prevented any fouling. Today, the substances used must comply with strict standards to avoid unnecessary environmental pollution.
After the toxic effect of the biocides used is limited, the most suitable type of antifouling should be used, depending on the requirements. A main distinction is made between the following types: Hard antifouling, soft antifouling, thin layer antifouling
and 2-component antifouling based on epoxy resin.
Hard antifouling consists of a water-insoluble carrier resin containing the biocides. These are washed out of the resin matrix by water over time. As long as there is enough active substance on the surface, the antifouling effect is given.
The biocide release and thus the effect are not constant; if the coating is new, a relatively large amount of biocide is released, while afterwards the biocide has to travel an ever longer distance through the matrix, reaches the surface more slowly and has a decreasing effect there.
Another disadvantage is that over time a thick, porous and unstable resin layer builds up. In order to avoid this, the old antifouling layer should be removed before each painting.
The advantage of hard antifouling is its high mechanical load capacity. Ships that are often launched and de-launched, that are trailered or even very fast boats should be painted with hard antifouling.
In the group of soft antifouling paints, a distinction is made between conventional eroding and self-polishing antifouling paints. Both types consist of a soft resin matrix which contains the biocides, which dissolves slowly in water and is removed by friction, e.g. sailing. Accordingly, there is always an optimum amount of fresh biocide on the surface, which inhibits fouling.
The difference between the two types is of a chemical nature and, in the case of conventionally eroding paints, causes the biocide to be released somewhat more irregularly over time. However, the price is often lower.
In contrast to hard antifouling paints, however, there is generally a relatively constant release of toxins, which guarantees an even growth-inhibiting effect over time. The application of a thicker layer of antifouling thus enables a relatively constant and prolonged effectiveness. The biocide is not or hardly washed out at all, but develops its effectiveness only after the "spent" top layer of paint has been removed, as soon as it is on the newly exposed surface.
The advantage of this type of antifouling is that no thick porous paint layers are built up over the years. After rinsing and before a new coat of paint is applied, the old antifouling layer can be removed easily and relatively simply with a high-pressure cleaner.
The disadvantage, however, is that a lot of material is removed when driving fast and the paint layer can also be worn away prematurely during washing in and out, bouncing and transport. Soft antifouling is not suitable for fast boats that reach speeds above 25 kn. Ships lying in flowing waters also risk that the soft antifouling application will be washed off prematurely.
Thin-film antifouling almost always consists of a relatively thin hard matrix to which Teflon-based additives are added. The antifouling effect of the biocides contained in the matrix is supported by the special nature of the paint surface, which is due to the Teflon.
If the biocides are washed out after the season, a new application of the antifouling paint must be carried out. However, as the existing layer is very thin, there is no need for the complete removal as it is necessary with hard matrix paints, as no thick layer of paint is formed in a comparable time.
A disadvantage that should not be overlooked is that thin-film antifouling can in principle only be painted over with itself. If one wants to change antifouling type, the entire old coating of thin-film antifouling must be removed before one can start a new paint application.
2-component antifouling based on epoxy resin results in an extremely hard coating of the underwater hull, which contains copper or zinc powder as biocide. The metal powder is very slowly washed out of the epoxy matrix and thus develops its effect. To maintain this effect over time, the surface should be lightly sanded every 2 to 4 years.
Another important effect of this epoxy coating is the protection against osmosis, after the epoxy resin provides an almost 100% moisture barrier.
The manufacturers often advertise these products with a 10-year period of effectiveness, but the cost of applying this material is correspondingly high.
Apart from the optimal choice of antifouling type, there are a number of other aspects to consider:
Antifouling paint - except the latter, which is based on epoxy resin - does not form a waterproof layer. The surface of the underwater hull must therefore, depending on the nature of the construction material, first be protected from contact with water. Wood, steel and GRP hulls are given a waterproof primer, which is adapted to the material, before being treated with antifouling paint. Particularly with steel hulls, the suitability of the antifouling paint must be checked to avoid problems due to galvanic corrosion.
If an antifouling paint is renewed, it is essential to ensure that the new paint is compatible with the old one. A barrier layer may be used to apply a new paint that is not directly compatible. If in doubt, the entire old coating must be removed.
The timing of the painting, in relation to watering, is also important. Depending on the type of paint and the manufacturer, the time between painting and watering may vary from a few hours to several months. A minimum drying time before watering is also specified and varies from product to product depending on the manufacturer.
Hard antifouling consists of a water-insoluble carrier resin containing the biocides. These are washed out of the resin matrix by water over time. As long as there is enough active substance on the surface, the antifouling effect is given.
The biocide release and thus the effect are not constant; if the coating is new, a relatively large amount of biocide is released, while afterwards the biocide has to travel an ever longer distance through the matrix, reaches the surface more slowly and has a decreasing effect there.
Another disadvantage is that over time a thick, porous and unstable resin layer builds up. In order to avoid this, the old antifouling layer should be removed before each painting.
The advantage of hard antifouling is its high mechanical load capacity. Ships that are often launched and de-launched, that are trailered or even very fast boats should be painted with hard antifouling.
In the group of soft antifouling paints, a distinction is made between conventional eroding and self-polishing antifouling paints. Both types consist of a soft resin matrix which contains the biocides, which dissolves slowly in water and is removed by friction, e.g. sailing. Accordingly, there is always an optimum amount of fresh biocide on the surface, which inhibits fouling.
The difference between the two types is of a chemical nature and, in the case of conventionally eroding paints, causes the biocide to be released somewhat more irregularly over time. However, the price is often lower.
In contrast to hard antifouling paints, however, there is generally a relatively constant release of toxins, which guarantees an even growth-inhibiting effect over time. The application of a thicker layer of antifouling thus enables a relatively constant and prolonged effectiveness. The biocide is not or hardly washed out at all, but develops its effectiveness only after the "spent" top layer of paint has been removed, as soon as it is on the newly exposed surface.
The advantage of this type of antifouling is that no thick porous paint layers are built up over the years. After rinsing and before a new coat of paint is applied, the old antifouling layer can be removed easily and relatively simply with a high-pressure cleaner.
The disadvantage, however, is that a lot of material is removed when driving fast and the paint layer can also be worn away prematurely during washing in and out, bouncing and transport. Soft antifouling is not suitable for fast boats that reach speeds above 25 kn. Ships lying in flowing waters also risk that the soft antifouling application will be washed off prematurely.
Thin-film antifouling almost always consists of a relatively thin hard matrix to which Teflon-based additives are added. The antifouling effect of the biocides contained in the matrix is supported by the special nature of the paint surface, which is due to the Teflon.
If the biocides are washed out after the season, a new application of the antifouling paint must be carried out. However, as the existing layer is very thin, there is no need for the complete removal as it is necessary with hard matrix paints, as no thick layer of paint is formed in a comparable time.
A disadvantage that should not be overlooked is that thin-film antifouling can in principle only be painted over with itself. If one wants to change antifouling type, the entire old coating of thin-film antifouling must be removed before one can start a new paint application.
2-component antifouling based on epoxy resin results in an extremely hard coating of the underwater hull, which contains copper or zinc powder as biocide. The metal powder is very slowly washed out of the epoxy matrix and thus develops its effect. To maintain this effect over time, the surface should be lightly sanded every 2 to 4 years.
Another important effect of this epoxy coating is the protection against osmosis, after the epoxy resin provides an almost 100% moisture barrier.
The manufacturers often advertise these products with a 10-year period of effectiveness, but the cost of applying this material is correspondingly high.
Apart from the optimal choice of antifouling type, there are a number of other aspects to consider:
Antifouling paint - except the latter, which is based on epoxy resin - does not form a waterproof layer. The surface of the underwater hull must therefore, depending on the nature of the construction material, first be protected from contact with water. Wood, steel and GRP hulls are given a waterproof primer, which is adapted to the material, before being treated with antifouling paint. Particularly with steel hulls, the suitability of the antifouling paint must be checked to avoid problems due to galvanic corrosion.
If an antifouling paint is renewed, it is essential to ensure that the new paint is compatible with the old one. A barrier layer may be used to apply a new paint that is not directly compatible. If in doubt, the entire old coating must be removed.
The timing of the painting, in relation to watering, is also important. Depending on the type of paint and the manufacturer, the time between painting and watering may vary from a few hours to several months. A minimum drying time before watering is also specified and varies from product to product depending on the manufacturer.
YACHT SERVICE - Antifouling Lake Maggiore.
The specialist for boat maintenance advises and carries out antifouling coatings.
YACHT SERVICE - Antifouling Lake Maggiore
will be happy to advise you on the optimum antifouling type and carry out the appropriate application with antifouling paint.
Antifouling Lake Maggiore
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