# How to Tell Fiberglass Cracks From Gelcoat Crazing on Your RV, Step by Step

Canonical: https://theocrv.com/blog/how-to-tell-fiberglass-cracks-from-gelcoat-crazing/
Business: OCRV Center, Yorba Linda, CA. Serving Mission Viejo, California.
Phone: (949) 799-3387 | Email: info@ocrvcenter.com

Category: How-To Guides | Published: 2026-06-08

Here is the quick test. If the lines are shallow, weblike, and you cannot feel them with a fingernail, that is gelcoat crazing, a surface issue. If your nail catches in the line or it runs single-file from a stress point, the fiberglass underneath is likely involved, and that is a structural repair, not a cosmetic one.

## Step one: look at the pattern

Crazing shows up as a spidery network of fine lines, often across a broad area that flexes or bakes in the sun. A structural crack is usually a single line, sometimes radiating from a corner, a fixture, or an impact point.

## Step two: use your fingernail

Drag a nail across the line. Crazing sits on the surface and feels smooth. A real crack has depth and will catch the nail edge.

## Step three: check what is behind it

- Cracks at a slide corner or window corner suggest flex or stress
- Lines that appear after an impact point to a fiberglass fracture
- Broad hazy webbing on a flat panel is usually just gelcoat
- A soft or spongy feel around the crack means water and delamination

## Why does the difference matter for the repair?

Crazing can often be sanded and refinished. A structural fiberglass crack has to be ground out, backed, rebuilt with laminate, and only then refinished, or it comes right back.
Refinishing over a real crack is the most common shortcut we undo. It looks fine for a season, then the line telegraphs back through the new gelcoat.

## When should you stop guessing and bring it in?

If the nail catches, if the area feels soft, or if the line sits at a stress corner, let a shop map it. Some cracks look minor from outside and hide a spreading fracture beneath the skin.
> Not sure if it is crazing or a crack? OCRV Center handles both at our Yorba Linda shop, and Mission Viejo owners drive up so we can tell the surface issues from the structural ones before the repair starts.