Washing and reproofing your boat canopy: mould, stains and windows

Short answer

Brush off dirt and rinse the canopy with water. Wash with a mild solution of washing-up liquid and lukewarm water. Rinse thoroughly and let it air dry. If the canopy has mould stains, use a weak bleach solution on the fabric, not on the windows. Once the canopy is clean and completely dry, you can reproof it.

What you need

Wash the canvas while it is fitted or laid out on land. Check the fabric label before using bleach. The recipes below are from Sunbrella and apply to their acrylic fabric.

Washing step by step

1. Brush off loose dirt, leaves and bird droppings.
2. Mix 1 teaspoon (4 ml) of washing-up liquid in 1 cup (250 ml) of water, or the same proportions in a bucket.
3. Wash with a soft brush and let the solution soak in for a while.
4. Rinse until all the soap is gone. Residue attracts new dirt.
5. Let the canvas air-dry completely before folding it.

Mould

Mildew grows on dirt left on the fabric. For mildew, Sunbrella recommends 1 teaspoon (4 ml) of washing-up liquid and 1 teaspoon (4 ml) of bleach per cup (250 ml) of water. Heavy mildew may need more bleach. Rinse thoroughly afterwards.

• Bleach can fade other fabrics, seams and cushions. Test on a hidden spot first.
• Keep bleach away from windows, zips and the boat's deck.
• Do not let bleach water run into the lake or sea.

For mould inside the boat, see damp and mould in the boat.

Waterproof

When water no longer beads on the fabric, the canopy needs reproofing. Washing also removes some of the protection.

1. The canopy must be clean and completely dry.
2. Choose a warm day. 303 specifies above 21 °C (70 °F) and full sun.
3. First test on a hidden spot to make sure the colour doesn't run.
4. Spray evenly until the fabric is wet, from 20 to 30 cm away. Overlap the spray passes.
5. Wipe off any spray that lands on windows, vinyl, wood and metal immediately.
6. Let it cure for 12 to 24 hours before rain hits the canopy.

The spray is flammable until it has dried. Work in a well-ventilated area and avoid sparks and open flames.

Windows and zips

• Rinse the windows with plenty of water before wiping, so sand doesn't scratch them.
• Wipe with a soft cloth and mild soapy water. Don't use solvents.
• Don't fold the canopy so the windows get sharp creases. Roll them instead, with a soft cloth in between.
• Brush salt and sand out of the zips. If a zip is stiff, lubricate it with a product made for zips.
• Broken zips and seams are best repaired by a canvas maker. Small tears can be patched temporarily with canvas repair tape.

Storing over winter

Only put the canopy away when it is clean and completely dry. Store it somewhere airy and dry, not in a sealed plastic bag. More on winter storage in winter storage for your boat and covering your boat for winter.

DIY or canvas maker

Washing and proofing you can do yourself. Most people leave new canvas windows, zip replacements and worn seams to a canvas maker. Find canvas makers and boatyards under Marinas & boatyards.

Frequently asked questions