How To Fix Spider Cracks, Hairline Cracks, and Crazing in Boat Gelcoat [MATERIALS LIST👇] | BoatUS
Like 4 Dislike 0 Published on 3 Apr 2020
BoatUS Magazine's Mark Corke shows you how to easily repair those pesky spider cracks that show up 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!
Before you tackle repairing hairline cracks in gelcoat, you'll need to prepare the area well by washing and cleaning with acetone. Then you'll drill out the gelcoat crazing using a dremel tool, just scratching the laminate but not going into it. You'll mix up your gelcoat, add the catalyst and a little colloidal silica to help thicken it, and apply it to the spider cracks. Use an old credit card to smooth it down, then let dry. Wet sand using wet/dry sandpaper wrapped around a block, then use a finer grain to further smooth it. Apply a compound and buff, apply a glaze and buff again. Finish using a wax and buff with a clean cloth.
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. Acetone is widely available.
http://www.evercoat.com/product-detail/base-part/100581/us/
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-ScotchBlue-24-in-x-30-yd-Pre-Taped-Painter-s-Plastic-with-Edge-Lock-and-Dispenser-PTD2093EL-24-s/204344770
Dremel rotary tool
https://www.dremel.com/en_US/products/-/show-product/tools/200-series-rotary-tool
Dremel bit
https://www.dremel.com/en_US/products/-/show-product/accessories/7150-diamond-wheel-points
Premixed gelcoat for almost any boat color
https://www.iboats.com/shop/paint-and-maintenance/fiberglass-and-epoxy-boat-repair/boat-gel-coat-repair.html
NOTE: The catalyst is included when you buy the gelcoat.
Syringes: cheapest I've found from Walmart
https://www.walmart.com/ip/Monoject-Curved-Tip-Syringe-12mL-Pack-of-4/500588759
Colloidal silica: For thickening the gelcoat
https://www.westmarine.com/buy/west-system---406-colloidal-silica-filler-5-1-2-oz--323618
Plastic mixing sticks: West System
https://www.westmarine.com/buy/west-system--mixing-sticks-8-pack--318287?cm_mmc=PS-_-Google-_-GSC%3ENonB%3EProduct%2520Type-_-318287&product_id=318287&creative=108421551244&device=c&matchtype=&network=g&gclid=Cj0KCQjw7qn1BRDqARIsAKMbHDbN_kRv1Zu0bECYXg7YBrIYKjVPD_pCYMSb8cmgGhkKAym9FSXNbucaAkRiEALw_wcB
Respirator: Available at home improvement stores
https://www.3m.com/3M/en_US/company-us/all-3m-products/~/3M-Half-Facepiece-Respirator-Assembly-6291-07002-AAD-Medium-with-3M-Particulate-Filters-2091-07000-AAD-P100-24-EA-Case/?N=5002385+8709322+8711405+3294780266&preselect=8720539+8720550+8720785&rt=rud
Wet/dry sandpaper (available at home improvement stores)
https://www.westmarine.com/buy/3m--wetordry-sandpaper-sheets-assorted--18359208?cm_mmc=PS-_-Google-_-GSC%3ENonB%3EVendors-_-18359208&product_id=18359208&creative=108421561444&device=c&matchtype=&network=g&gclid=Cj0KCQjw7qn1BRDqARIsAKMbHDZQHJiyunYVeJYAWmYlbKUXu0bD4P6THGX4WLozGnDIYGwtt5rDcBsaAojzEALw_wcB
Polishing compound
https://www.mirka.com/Polarshine-45-Polishing-Compound-1L-7994510111/
Buffing machine. The one I have is no longer available but this is the equivalent
https://www.dewalt.com/products/power-tools/polishers-shears-and-nibblers/7--9-variable-speed-polisher-with-soft-start/dwp849x
Polishing pad
https://www.westmarine.com/buy/3m--double-sided-polishing-pad-9--2091122?recordNum=21
Polish/Glaze: Also available in West Marine
https://www.3m.com/3M/en_US/company-us/all-3m-products/~/3M-Marine-Finesse-it-II-Glaze/?N=5002385+3293242387&rt=rud
https://www.westmarine.com/buy/3m--finesse-it-ii-finishing-material-pint--569486?recordNum=1
Collinite Wax Bottle looks different now but same product.
https://www.westmarine.com/buy/collinite--no-925-fiberglass-boat-wax--4758322
For more information, visit https://www.boatus.com/Expert-Advice.
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