Fiberglass Tape vs Cloth — When to Use Each

Fiberglass tape and fiberglass cloth serve different roles in composite repair and construction. Choosing the correct reinforcement material improves strength, durability, and ease of application.

Fiberglass Tape

• Narrow woven strips designed for seams, corners, and joints

• Ideal for reinforcing structural connections

• Conforms well to curved or angled surfaces

• Often used over epoxy fillets

Fiberglass Cloth

• Wide sheets used for covering large areas

• Provides uniform reinforcement across panels

• Common for hull repairs and laminate buildup

Tape is typically used where directional strength is needed, while cloth is preferred for broad surface reinforcement.

Types of Fiberglass Cloth and Tape

West Marine sells fiberglass as chopped strand matt, cloth, tape and roving.

Chopped Strand Mat

Chopped strand mat is a flat sheet of randomly orientated fibers that leaves a flat, rather than a rippled surface. This material works well as an external layer, as well as between other layers of cloth.

Fiberglass Cloth

Fiberglass cloth woven much like the oxford weave of a shirt, wherein the weft threads pass over and under the warp threads in a 90 degree pattern.

Fiberglass Tape

Fiberglass tape is woven like fiberglass cloth and available in various widths and lengths. One difference between fiberglass tape and cloth is that tape has a non-raveling edge unlike the edge of fiberglass cloth which easily unravels and comes apart. Fiberglass tape is used for creating champers, fillets, tabbing bulkheads and for other purposes.

Fiberglass Roving

Fiberglass roving consists of large bundles of fibers woven in a coarse fabric that is used for flexible strength, and for building up thicknesses of laminates. Generally, roving and mat are alternated for several layers to create the desired thickness.

The weight of fiberglass cloth, tape and roving is quantified as the material’s weight per square yard.

Tape Weights & Widths Explained

Fiberglass tape is available in various fabric weights and widths to match different repair requirements.

• Lighter weights conform easily to complex shapes and are suitable for small repairs

• Heavier weights provide greater strength and durability

• Narrow widths are ideal for tight seams and edges

• Wider tapes cover larger joints and distribute loads more effectively

Selecting the appropriate size helps balance ease of application with structural performance.

Structural vs Cosmetic Reinforcement

Fiberglass tape can serve both strength-critical and appearance-focused repairs.

Structural Reinforcement

• Restores load-bearing capability

• Prevents cracks from propagating

• Used in hull seams, bulkheads, and high-stress areas

Cosmetic Reinforcement

• Stabilizes minor cracks or surface defects

• Often followed by fairing and finishing

• Improves surface durability

Understanding the repair goal helps determine the number of layers and tape weight required.

Compatibility With Epoxy, Polyester & Vinyl Ester

Fiberglass tape can be used with multiple resin systems, but compatibility influences strength and adhesion.

• Epoxy Resin: Provides the strongest bond and highest moisture resistance

• Polyester Resin: Common for traditional fiberglass repairs but less adhesive

• Vinyl Ester Resin: Offers improved durability and water resistance

Epoxy systems are generally preferred for critical repairs and bonding to diverse materials.

Common Marine Repair Applications

Fiberglass tape is widely used across many boat repair scenarios:

• Reinforcing hull seams and chines

• Strengthening joints between panels

• Repairing cracks and splits

• Bonding bulkheads and stringers

• Reinforcing deck-to-hull connections

Its ability to conform to corners makes it especially valuable for structural repairs.

How to Apply Fiberglass Tape Properly

Proper application ensures maximum strength and adhesion.

Typical steps include:

1. Prepare and clean the surface

2. Apply resin to the repair area

3. Position the tape over the wet surface

4. Saturate the tape thoroughly with resin

5. Remove air bubbles using a roller or spreader

6. Allow the laminate to cure before finishing

Fully wetting the fibers is essential for achieving structural integrity.

Seam Reinforcement Techniques

Seams and joints are common failure points in composite structures. Fiberglass tape distributes loads across the joint, reducing stress concentration.

Best practices include:

• Applying tape over a properly shaped epoxy fillet

• Using multiple layers for high-strength areas

• Extending reinforcement beyond the damaged zone

• Ensuring full resin saturation

Proper seam reinforcement significantly improves long-term durability.

Boat-Specific Use Cases

Fiberglass tape is versatile and suitable for many marine components.

Hull Repairs

• Reinforcing cracks, splits, or seams

Deck Repairs

• Strengthening high-traffic areas

Bulkheads & Structural Panels

• Bonding panels to hull structures

Interior Components

• Securing stringers, frames, or supports

Matching tape selection to the specific component ensures reliable results.

Estimating How Much Tape You Need

Material requirements depend on repair size, number of layers, and tape width.

Factors affecting quantity include:

• Length of seams or joints

• Structural requirements

• Overlap between layers

• Waste during cutting and placement

Purchasing sufficient material helps ensure continuous reinforcement without interruptions.

Shop fiberglass tape and cloth at West Marine.

Fiberglass cloth and tape are reinforcing fibers that create structural strength when combined with polyester, vinylester or epoxy resin. These materials are used in a wide variety of boat building and repair applications. Examples include hull layups, reinforcing hulls and decks, repairing cracks and holes and patching up damaged areas.