BoatUS Magazine's Mark Corke shows you how to easily fix gelcoat spider cracks, hairline cracks, and crazing in your boat's fiberglass gelcoat. While this may seem like a scary project, with a little time and patience, it's something you can do yourself with great results!

It's important to differentiate between stress cracks and spider cracks (though the terms are often used interchangeably). Stress cracks are generally deeper, involve more than just the gelcoat, have an underlying cause (structural or impact), and are likely to come back if the underlying cause isn't addressed first. Spider cracks are less likely to come back as they're superficial and often caused by age, UV, weather, or dings.

Here's a helpful list of the tools and products I used in the video:
Acetone: I used an Evercoat product, linked here, but any acetone would be fine.
http://www.evercoat.com/product-detai...

Pretaped Masking Plastic: 3M brand, readily available at Home Depot. You can also find it in Sherwin Williams stores and some West Marine stores have it.
https://www.homedepot.com/p/3M-Scotch...

Dremel rotary tool:
https://www.dremel.com/en_US/products...

Dremel bit: Silicon carbide grinding bit in a bullet or cone shape
https://www.dremel.com/us/en/p/84922-...
OR tungsten carbide bit (bullet or cone), but be very careful not to grind too deep.

Premixed gelcoat for almost any boat color:
https://www.iboats.com/shop/paint-and...
NOTE: The catalyst is included when you buy the gelcoat.

Syringes: cheapest I've found from Walmart
https://www.walmart.com/ip/Monoject-C...

Colloidal silica: For thickening the gelcoat
https://www.westmarine.com/buy/west-s...

Plastic mixing sticks: West System
https://www.westmarine.com/buy/west-s...

Respirator: Available at home improvement stores

Wet/dry sandpaper: (available at home improvement stores)
https://www.westmarine.com/buy/3m--we...

Polishing compound:
https://www.mirka.com/Polarshine-45-P...

Buffing machine: The one I have is no longer available but this is the equivalent
https://www.dewalt.com/products/power...

Polishing pad:
https://www.westmarine.com/buy/3m--do...

Polish/Glaze:
https://www.3m.com/3M/en_US/company-u...
https://www.westmarine.com/buy/3m--fi...

Collinite Wax:
https://www.westmarine.com/buy/collin...

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0:00 Introduction
0:23 Wash area & wipe with acetone
0:40 Mask off work area
1:01 Open up cracks
1:40 Stir gelcoat well
2:04 Decant gelcoat into cup
2:46 Mix well
3:08 Thicken gelcoat with colloidal silica
3:31 Apply thickened gelcoat
3:57 Scrape off excess gelcoat
4:12 Let dry overnight
5:01 Remove tape
5:15 Wet sand with 220 grit paper around block
5:56 Wet sand with 400 grit paper around wood block A Boatus
6:18 Wipe with clean rag
6:35 Apply rubbing compound with rag
6:52 Buff with polisher
7:15 Apply glaze
7:31 Buff #2
7:47 Apply wax with applicator pad
8:08 Buff #3 with clean pad