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As summer rolls around, boat owners across the country prepare to launch their vessels into sunlit marinas, sparkling lakes and open seas. The warmth of the season marks not just the perfect time to enjoy the water, but also the ideal opportunity to give your boat some much-needed care and attention. A clean, well-kept boat isn’t just about aesthetics, remember, it’s a key factor in performance, safety and longevity.
If your boat is made from Glass Reinforced Plastic (GRP), otherwise known as fibreglass - and chances are it is - you’re in good company. GRP is favoured across the marine industry for its strength, durability and cost-effectiveness. Its corrosion resistance and flexibility makes it perfectly suited to withstand both saltwater and freshwater environments. However, like any premium material, GRP needs proper care to stay in peak condition.
Cleaning a GRP boat isn’t as simple as hosing it down. Harsh weather, UV rays, algae and salt can all take their toll on your GRP boat’s surface. Without the right cleaning techniques, products and materials, you risk damaging the gelcoat, inviting microcracks and even weakening the structure over time. Worse still, using the wrong solvent or abrasive cleaner can dull or degrade the finish, leaving your boat looking prematurely aged.
In this guide, Fibreglass Supplies will help you tackle the cleaning process with confidence. Whether you’re a seasoned fibreglass technician or a first-time boat owner, we’ll walk you through the steps, tools and vital products you need to keep your GRP boat clean, shiny and, most importantly, seaworthy.
GRP (Glass Reinforced Plastic) is a composite made from polyester resin reinforced with glass fibres. The surface is protected by a gelcoat, which gives the boat its smooth finish and colour. This gelcoat is tough, but not invincible. It can oxidise, stain and fade if not maintained.
Over time, salt residue, diesel fumes, algae, bird droppings and general grime accumulates on the surface. If these contaminants are left unchecked, they can:
That’s why GRP cleaning requires gentle but effective products, proper tools and a consistent approach.
Before starting, gather the following tools and products - ideally ones designed specifically for GRP or marine use:
Avoid using bleach, harsh degreasers or kitchen scouring pads as they can scratch and dull the surface irreversibly.
Start by thoroughly rinsing your boat with clean, fresh water. Use a hose with good pressure to dislodge loose salt, silt and debris. This prevents grit from scratching the surface during scrubbing.
Mix your marine-safe cleaner with water according to the manufacturer’s instructions. Use your soft-bristle brush to work section by section, starting from the top deck and working your way down. Rinse each section before moving to the next to avoid streaks or soap drying onto the surface.
For diesel stains, rust marks or resin residues, dampen a cotton rag with a small amount of acetone or isopropanol and gently rub the affected area. Always wear gloves and ensure good ventilation. Avoid excessive solvent use, especially near decals or painted stripes.
Use microfibre towels or white cotton rags to hand-dry all surfaces. This prevents water spots and allows you to inspect for missed grime or imperfections.
Once clean and dry, apply a quality marine polish or UV-protective wax. This step not only enhances the shine but also forms a protective layer against UV damage and grime buildup.
Regular maintenance reduces long-term repair costs and helps preserve your boat’s resale value.
Each of these mistakes can weaken the gelcoat or degrade the finish, leading to expensive restoration work.
Remember, keeping your GRP boat clean isn’t just about appearances, it’s about protecting your investment, ensuring safety and extending the life of your vessel. With the right tools and cleaning approach, you can keep your boat looking pristine all summer long and beyond. Whether you're polishing the hull for a family trip or maintaining fleet boats for charter, clean and cared for GRP means better performance and fewer headaches down the line.
So next time you're docked or pulled ashore, take the time to follow these steps - you’ll definitely thank yourself next season.