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Restore the Shine to Fiberglass

Gelcoat is often touted as a maintenance-free material, but that's not quite the whole story. Here's how to restore the shine.

Let's face it. Your boat may look a little bit less than its best right now, especially if it has been quietly hibernating over the winter. So a bit of TLC before the season starts could go a long way to enhancing her appearance. There's more to polishing the fiberglass than just rubbing a bit of car wax onto the gelcoat, however. So set aside some time for your first boat project of the year. With a bit of commitment, care, and the correct materials, you'll not only bring back that showroom shine but you'll also protect your investment and add an extra layer of protection for the coming season.

  1. STEP 1

    Washing your boat is an important first step. Skip this step and you could be rubbing dirt into the surface, which will mar your gelcoat and cause long-term damage. (See "A Note About Boat Washing" below for more information.) Don't be tempted to use dishwashing detergent.

    Washing the Boat

    Although it's great at removing dirt, grime, and previous applications of wax, it can leave behind streaks that are almost impossible to remove.

  2. STEP 2

    Dry the boat with a chamois that has been wetted and well wrung out. Rinse it often in a bucket of hot, clean water. When the boat is completely dry, rub on some compound with a terry cloth or polishing pad. Work on one 3-foot-square area at a time and be generous with the compound, using about a tablespoon-sized dollop for each section.

    Compound with Polishing Pad

    This shows up well on the blue hull in the photo; it's harder to see how much you are applying to a white gelcoat surface.

  3. STEP 3

    I prefer to use a Makita or DeWalt slow-speed polisher with a medium foam pad for the compound. The compound won't clog up as fast on foam pads as it will on wool mops. However, it's worth noting that wool pads are a bit more aggressive than foam pads. They cut faster, so there's a greater chance of damaging the gelcoat.

    DeWalt Polisher with Foam Pad

    Set the machine to about 2,000 rpm, then place the pad in contact with the surface before pulling the trigger. This prevents the tool from skidding off and you from potentially losing control. Use firm pressure — just enough to keep the full pad surface in contact with the boat. Move the pad from side to side and then up and down in slow deliberate strokes.


    To achieve the best results, apply the compound on an overcast day or in the shade. Exposure to direct sunlight will cause the compound to dry too fast.

    You should see much of the chalking and scratches start to disappear. Stop when the pad is having no more effect. You'll notice that the surface is already much improved.

  4. STEP 4

    After you have compounded the entire boat, wipe the surface with a microfiber towel. Then swap out the medium pad for a fine one, and apply a coating of 3M Finesse-It — essentially a very fine cutting compound — to one 3-foot section at a time. Then buff this using the polisher at 3,000 rpm, using the same technique described in the previous step.

    Buffing Hull Using Polisher

    Keep the polisher moving until there is no trace of polish or swirl marks. By the time you're done, you should be able to see your reflection in the boat's surface. You're not quite finished, however.

  5. STEP 5

    The final important step is to apply a good coat of wax. I favor Collinite 25. A little goes a long way, and it leaves a deep, lustrous finish that will repel dirt and water spots for the coming year. If you keep your boat in the South, where it's beaten by the subtropical sun, you may need a second coat midseason.

    Applying a Coat of Wax

    Apply the wax by hand using a foam applicator pad or clean, dry microfiber towel. Rub a small amount of wax in a circular motion until dry, again working in small sections. Finally, buff it with a clean towel. Your arms may be aching at the end of the day, but your hard work will pay handsomely with a beautiful shine!

A Note About Boat Washing

BoatUS Foundation tests showed that the label "biodegradable" doesn't mean much when it comes to boat soaps. Technically it means that the ingredients break down into harmless components when they go through typical wastewater treatment, but we know that likely won't happen with boat soaps. So while the label sounds nice, it doesn't mean much. Also, the results of the Foundation's tests varied greatly: One soap labeled "biodegradable" can be hundreds of times less degradable than another with the exact same label.

When using boat soaps, those products that say "dilute with water in a bucket" are much less toxic than those products that are applied as a paste or a spray. When you have a troublesome spot, use one of the spray or paste cleaners, but wipe up with a rag instead of rinsing into the water. Our general advice is to wash your boat on the hard, away from the water's edge. If you must clean your boat in the water, we recommend frequent freshwater rinsing to minimize the buildup of dirt.

Tech Support

Degree Of Difficulty

Tools and Materials

  • Low-speed polisher
  • Microfiber towels
  • Chamois
  • 3M Imperial Compound and Finishing Material or similar
  • 3M Finesse-It Finishing Material or similar
  • Collinite 925 wax or similar
  • Pad and polishing pads for polisher, such as 3M’s 33274 (medium) and 33275 (fine)


Allow a complete day for the topsides of a 26-foot center-console.


Depends on boat size and level of detailing required. Expect to spend about $200 for compound, polish, and pads for a 26-footer. A decent polisher/buffer will set you back about $200.

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Mark Corke

Contributing Editor, BoatUS Magazine

A marine surveyor and holder of RYA Yachtmaster Ocean certification, BoatUS Magazine contributing editor Mark Corke is one of our DIY gurus, creating easy-to-follow how-to articles and videos. Mark has built five boats himself (both power and sail), has been an experienced editor at several top boating magazines (including former associate editor of BoatUS Magazine), worked for the BBC, written four DIY books, skippered two round-the-world yachts, and holds the Guinness World Record for the fastest there-and-back crossing of the English Channel — in a kayak! He and his wife have a Grand Banks 32.