GRP decks with a moulded anti-slip texture are durable, lightweight and robust. However, as they age, they become difficult to keep clean. Just as on smooth surfaces, the gelcoat weathers here too, and dirt becomes lodged in the recesses. The contrast is particularly striking when the hull and superstructure gleam after a fresh polish, whilst the deck remains dull and dirty.
You won’t get very far with ordinary brushes and deck cleaners – the dirt in the grooves remains. Traditional polishing doesn’t work either: sponges or lambswool only reach the peaks of the texture; the dirt remains in the valleys. With coarse textures, such as those found on older X-Yachts, the polishing materials are literally ground to pieces. The wear and tear is enormous, and the cleaning effect is virtually zero.
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After various experiments with different materials, a tip from the polish manufacturer led to a breakthrough: polish and a hard brush – though not applied by hand, but using a brush attachment on a cordless screwdriver. With the rotating brush, the polish works its way into even the deepest recesses, thereby removing stubborn dirt.
The result isn’t a high-gloss finish – which wouldn’t be desirable for an anti-slip mat anyway – but a noticeably cleaner, smoother surface. However, you shouldn’t underestimate the amount of work involved. Depending on the depth of the texture and the level of soiling, you’ll manage just 1.5 to 2 square metres on a single battery charge. The machine pulls quite hard, and it really takes it out of your arms. You should also mask off any wooden parts, as the brush spreads polish and loosened dirt liberally around the area.
It may not add any shine, but it does provide the desired cleaning effect
The choice of polishing compound is crucial. It should be water-based and wax-free so that it is easier to clean off. Products such as Mirka Polarshine 45, Sealine S1 or Menzerna Green Line are suitable. These so-called one-step polishes are coarse enough to sand away dirt; on smooth GRP, they would polish the surface from a matt finish to a high gloss. On textured decks, you won’t achieve a gloss finish, but you will achieve exactly the desired cleaning effect.
The method is simple: work on small areas, apply a generous amount of polish and work the surface first at a low speed, then at a slightly higher speed. An important tip: change the direction of rotation of the cordless screwdriver from time to time. This ensures you cover all sides of the indentations and keeps the brush working effectively.
After polishing, the surface must be thoroughly cleaned with a microfibre cloth and water. It is only when you wipe it down that you realise just how much material was actually involved. Once dry, wipe the surface again to remove any remaining dust. Next comes the polymer sealant: this prevents new dirt from settling quickly. If you’re treating a deck with little texture, you should take care: the sealant can make the surface very slippery.
Deck cleaning: A step-by-step guide
1. Initial cleaning
Stains can be removed effectively with a gelcoat cleaner. However, this method does not reach deep-seated dirt.
2. Preparation
Mask off the wooden parts, then apply a generous amount of sanding compound. Choose a medium-grit sanding compound.
3. Distribute
Apply the polish at a low speed and work it in at a higher speed. Whilst doing so, the direction of rotation …
4. Induction
… change position so that all edges are sanded. A fine mist of water keeps the work area damp.
5. Follow-up treatment
Thoroughly remove any polish residue and wipe with water; the surface is then sealed.
6. Monitoring
A direct comparison clearly shows just how effective the cleaning of the anti-slip surface is.
In a nutshell: a checklist to tick off
- Rough cleaning: Removing stains
- Preparation: mask off, apply polishing compound
- Share: Apply the polish
- Induction: Change the direction of rotation; keep it damp with a fine mist of water
- Follow-up treatment: Remove any polish residue, wipe with water, then seal
- Check: Check the results of the cleaning
Hauke Schmidt
Test & Technology editor
