Short answer
Do it in four steps: wash, compound away the oxidation with an abrasive polish, polish with a finer product and wax for protection. Dull, chalky gelcoat needs compounding. A glossy boat only needs wax. Wax at least once a season, ideally before launching.
What you need
| Step | Product | Tools |
|---|---|---|
| Wash | Boat shampoo | Sponge, soft brush |
| Compounding | Coarse compound | Rotary polisher, wool pad |
| Polishing | Fine polish | Dual-action or rotary polisher, foam pad |
| Protection | Wax or polymer/ceramic | By hand or by machine at low speed |
3M's procedure for boats follows the same order and changes pads between steps so that coarser product isn't carried over.
Step by step
- Wash and rinse off salt and dirt. Sand in the pad causes new scratches.
- Tape off decals, rubber strips and teak.
- Work half a square metre at a time with a little compound and moderate pressure. Don't let the machine sit still on edges.
- Wipe off with a clean microfibre cloth and check in raking light.
- Polish with a finer compound until the surface has a deep gloss.
- Wax and buff according to the manufacturer's instructions on drying time.
Common mistakes
- Work in direct sunlight – the product dries and smears.
- Rub too hard on edges, where the gelcoat is thin.
- Wax the antifouling or the non-slip on deck. It gets slippery.
- Forget that wax must be removed with acetone before you repair gelcoat.
Oxidation, chalking and yellowing
Gelcoat is broken down by UV light. The surface first turns dull, then chalky – it leaves white on your hand when you run a finger over it. Dark hulls and older boats are hit hardest. Here's how to decide which step you need:
| Surface condition | Start with |
|---|---|
| Glossy, just dirty | Wash and wax |
| Slightly dull | Polish and wax |
| Chalky, white on your hand | Rubbing compound, polish and wax |
| Deep scratches | Wet sanding, then rubbing compound |
| Yellowed waterline | Waterline cleaner before polishing |
Do a test patch first and start with the least aggressive product. If polish won't bring back the shine, go one step coarser. You can always remove more material, but never put it back.
Work from the top down: superstructure, deckhouse, then hull sides. Change or clean the pads often, as a clogged pad heats the surface and causes holograms. Stop a little short of taped edges and do the edges by hand. It's worth noting which products worked, so it goes faster next year.
DIY or order
Many boatyards offer polishing in connection with launching. Compare prices by requesting a quote through Marinpedia, and see more spring jobs in the spring commissioning checklist.
Frequently asked questions
How often should you wax your boat?
At least once a season. A boat kept in the water in strong sun benefits from two treatments.
Do I need a polisher?
Hand application is fine for wax. To remove oxidation you'll in practice need a machine.
Is ceramic coating better than wax?
It often lasts longer but requires more careful prep work. Follow the product instructions.
Can I polish the boat while it's in the water?
You can do the superstructure and deck, but the hull sides are much easier and safer to do while the boat is ashore before launching. Water and wash make power-tool work difficult.