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Polish perfectly: high-gloss treatment for your boat


It is the simplest form of pimp my boat: polishing a matt gelcoat. Whether by hand or with a machine, I’ll reveal the best trick.

A new season and a fresh look for the holy boat go well together. In contrast to any “dirty jobs”, such as overhauling the engine or replacing the boat toilet, a sparkling exterior is firstly not witchcraft and secondly, it is likely to attract admiration and perhaps even envious looks from the dock neighbors. Before you start your adventure, however, there are a few basic points to consider so that the desired result is actually achieved in the end.


  • Washing – only if the surface is really clean can it be polished and sealed afterwards.
  • Sanding – if the surface is old and correspondingly dull or worn, it must be sanded before polishing. Choose the abrasive or paste as fine as possible in order to protect the intact gelcoat.
  • Polishing – after applying the polish, wait until streaks appear, only then start polishing. When working with a polishing machine, make sure that the attachment does not develop too much heat due to too much pressure or too high a rotation speed!
  • Sealing – the polished hull must finally be protected with either UV-resistant wax or silicone products. Apply thinly, let it harden according to the manufacturer’s instructions and only then proceed to the final polish.

Gelcoat is the protective outer skin of GRP laminates, which is originally about 1.5 thin and becomes dull and matt over the years due to oxidation. Darker colors, which are particularly affected by environmental influences such as UV light from the sun, dirt or salt water, are particularly at risk. In addition, there is wear and tear from normal use, just think about it. The shame filing of fenders on the ship’s sides ensures that even a well-maintained boat has imperfect cosmetics. If you look at such surfaces through a microscope, they appear anything but smooth. Bumps and depressions caused by broken pieces enlarge the surface and offer dirt a much better surface to attack. Scratched surfaces are also extremely bad for the reflection of light, which creates the matt appearance of the gelcoat.


The first rule is: get as much of the existing substance as possible. And the newer the boat and the better the gelcoat is, the easier it is. The small holes can then be filled with polish or wax and smoothed. Looks good and protects the boat from harmful environmental influences and further pollution. If you take this to heart from the start, you will enjoy a smooth and reflective outer skin for a long time with relatively little effort.
If the damage is deeper than 1.5 mm, more drastic means must be used, such as a grinding paste that removes the bumps that have remained between the scratches so that shine is restored. When the time comes, experienced owners let themselves be told by a scrutinizing look, others may have to seek advice from a professional. It’s kind of a last resort before you have to paint the boat, quite an expensive proposition, especially since you should or should hire professionals to do it. The following applies: start with fine-grained means in order to remove as little as possible and only switch to the coarse if the desired success does not materialize.


Before you get serious about cosmetics, you have to face the most dull task of all: cleaning! This is not only about removing dirt with special cleaners (please use biodegradable products), but also old polishes or wax to create the cleanest possible surface. Then rinse thoroughly with fresh water. If the gelcoat is still intact, you can go to work with a polish without abrasives after it has dried in order to get the maximum amount of residual gloss out of the existing substance.

Areas with heavy abrasion (under the fenders) will, however, require a sanding treatment. Likewise, places on deck that are particularly exposed to sunlight. The experienced gelcoat nurse will always test a product for its effectiveness in a difficult-to-see area before working on larger and prominent areas. If grinding polish is used, the surface should be finally sealed with UV-resistant Teflon or wax products. Please make sure that none of these agents contain silicone, as this greatly reduces the adhesion of other care products or paint.


Polishing makes no more sense in cold or rain than in scorching heat. If you talk to professionals, you will find out that they use different products depending on the temperature and humidity. Polishing in the blazing sun is also not advisable, because the product dries too quickly on a warm surface and thus hinders distribution. You can often see eager owners at work in autumn after the boat has been washed out and washed, when the sun is no longer as powerful and it is still relatively warm during the day. In winter storage in a hall it would also work, but depending on the work that is being carried out on the surrounding boats, there can be too much dust. If the boat is outside, the seal provides good protection against the winter weather in autumn, but it should be washed and reworked in spring.


Good results when beautifying matte gelcoat surfaces require two different ingredients: patience and spit. Often several work steps are necessary, which drag out the process, which is why resourceful manufacturers offer products that do several steps at the same time in order to simplify and shorten the procedure. Sanding, polishing and sealing in one wash, so to speak. It works, but it is and will inevitably be a compromise. Combination pastes initially remove the surface like fine sandpaper, but become a polishing agent as soon as the abrasive particles are used up or ground up. Sounds good and works well, but if such a product is used on a surface that actually only needs a seal, for example on newer boats, there is a risk of inadvertent scratching. Therefore, such products should not be considered until the gelcoat is so faded or worn that grinding is indicated as part of therapy.


If you are in a hurry, you will tend towards machine polishing, but be careful, this can have undesirable consequences if you use a polishing machine incorrectly. And this also costs accordingly, because it should be powerful and also turn slowly (1500 revolutions per minute or less) in order to avoid overheating of the polished surface, which is almost the case with a fast rotating flex (approx. 10,000 rev / min) is preprogrammed. Of course, professionals have expensive professional machines because they need them every day for their job, but for hobbyists who only work on the gelcoat of their boat once or twice a year, a 500-euro device usually pays off not from. Doesn’t matter, because maybe you can borrow one or you go back to the beginnings and work by hand, with an old but clean cotton shirt. If this is too tedious for you, you can also use a special palm with an ergonomically shaped handle, where the polishing attachment can be changed. This saves energy and distributes the pressure better than a clumped T-shirt. Regardless of how, when manually refurbishing large areas of the fuselage, it is advisable to have an assistant with you who already starts polishing while you are still applying the product, because firstly it is faster and secondly because it prevents you from having to go between the two work steps too much time passes while the product dries and the result may look less perfect afterwards.


One more word about the contact pressure of the polishing machine, which should be carefully dosed because the more pressure, the more heat. And the more heat, the more offensive the grinding or polishing product and the surface treated with it react. Particular caution is required with lambskin attachments, because they are often used for the last step in which the high-gloss finish is produced. If you use too much pressure or too high revolutions here, you heat the surface too much, which could compromise the previous work steps and, unfortunately, the most desired surface gloss. So move the polishing machine in a circular motion frequently and replace the polishing head with a clean one every 15 to 20 minutes. (Usually the covers can be washed after use).
Conclusion: A nicely polished gelcoat dress suits every ship and can in most cases be realized by a layperson with a reasonable investment of time and money. The prerequisites for this are the right equipment, the right products and a dry, clean work environment that should neither be too hot nor too cold.


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