When it comes to boat building or repairs, choosing the right fiberglass reinforcement is one of the most important decisions you can make. Fiberglass gives your vessel its structure, strength, and durability — but not all fiberglass is the same. 

At True Composites, we carry trusted, marine-grade fiberglass materials like fiberglass cloth, chopped strand mat (CSM), and 1708 biaxial, each suited to different types of boats and applications. 

This guide will help you understand the differences between them, how to apply them, and which is best for your boat. 

Understanding Fiberglass Types 

Fiberglass is made from extremely fine glass fibers, formed into mats or woven into fabrics. These reinforcements are combined with resin to create strong, water-resistant structures perfect for marine use. 

Here are the primary types of fiberglass available at True Composites:

1. Fiberglass Cloth 

- Best for: Lightweight reinforcement, cosmetic repairs, and smooth surface finishing 
- Why use it: This woven fabric drapes easily and is perfect for kayaks, paddleboards, and boat decks. It wets out nicely and provides a refined finish. 

2. Chopped Strand Mat (CSM)

- Best for: General reinforcement, mold building, base layers 
- Why use it: Made from randomly oriented glass fibers bound with a resin-soluble binder, CSM adds thickness and provides a nice fiish. It wets out easily and bonds well with other layers. 

3. 1708 Biaxial Fiberglass

- Best for: Structural reinforcement such as hulls, transoms, stringers 
- Why use it: This heavy-duty option combines ±45° stitched fibers with a CSM backing for superior strength. Ideal for areas that require rigidity and impact resistance. 

Matching Fiberglass to Boat Types 

Each boat type has unique stress points and design needs. Here’s how to choose the right fiberglass for common builds: 

Small Boats (Kayaks, Canoes, Dinghies) 

- Recommended Fiberglass: Fiberglass Cloth 
- Why: Lightweight and easy to shape, it’s ideal for smooth, curved hulls and cosmetic finishes. 

Medium Boats (Bass Boats, Pontoon Boats, Runabouts) 

- Recommended Fiberglass: Chopped Strand Mat + Fiberglass Cloth or 1708 Biaxial 
- Why: CSM offers bulk and quick reinforcement. Cloth adds some strength. For transom or deck repairs, add 1708. 

Larger Vessels (Yachts, Cabin Cruisers) 

- Recommended Fiberglass: 1708 Biaxial 
- Why: For structural reinforcements like hulls, stringers, and bulkheads — 1708 offers unmatched durability and strength. 

Application Tips 

1. Choose the Right Resin: Polyester resin is common for CSM; epoxy pairs well with cloth and 1708 for stronger bonding. 
   2. Layer Strategically: You could start with CSM for bulk, layer with 1708 or cloth for structure, and finish with chopped strand mat to prevent print through.  
   3. Use a Roller: To eliminate bubbles and ensure full resin saturation. 
   4. Trim Excess Edges: Sand or trim excess between layers to maintain a clean profile. 

Where to Find These Products 

You can find all these fiberglass reinforcements and compatible resins in the Resin & Fiberglass collection at True Composites. 

Whether you're patching up a deck or building from scratch, using the right fiberglass will make all the difference in performance and longevity. 

Ready to Build? 

Explore our full line of fiberglass cloth, CSM, 1708 biaxial, and marine resins online. Need help choosing the right materials? Our team is here to support your next project — big or small. 

👉 Shop now at TrueComposites.com