Marine Fiberglass Manufacturing: What You Should Know

Ryan Franklin
January 18, 2023

Many people have heard of fiberglass but don't necessarily know what it is or how it's made. Marine fiberglass, in particular, is a material that's incredibly strong, light, and durable as long as the right type of fiberglass is used for the correct application. Here, we'll take a look at what marine fiberglass is and how it's created.

What Is Marine Fiberglass?

Fiberglass is a man-made substance made of reinforced plastic that’s overlaid with glass and woven material to create a type of fiber. In some cases, it can be a glass-reinforced plastic fiber. Sometimes fiberglass is called glass-reinforced plastic, GRP, or fiberglass-reinforced plastic, FRP.

In the marine industry, fiberglass can be used for countless things; the most commonly known are yachts and larger boats. In addition, due to the high resistance to wear, it is also frequently used for surfboards and dinghies. Since it has high moisture resistance, is insulated from electrical components, and has advantageous physical strength, it can be used in countless applications.

Different Types of Marine Fiberglass

There are three common types of fiberglass, organized by the types of fibers and how they're arranged. These marine fiberglass designations apply not only to boat construction but also to any repairs that occur to marine fiberglass. Generally speaking, glass fiber can be flattened into a sheet, made into a woven fabric, or arranged randomly.


Mat fiberglass, also known as chopped-strand mat, is made from the same fibers as E-glass. The two or three-inch fibers are arranged randomly in all directions. Mat fiberglass is held together with a resin-soluble binder but requires a large amount of resin. Mat fiberglass is relatively waterproof and can be smoothed considerably with sanding. Mat is used most often for building up the layered thickness in layups.


E-glass is made from melted plastic that's spun into ultra-thin fibers. Those fibers are then consolidated and woven into fiberglass cloth. E-glass is one of the most popular and common types of fiberglass and is the most frequently used for boat building.

E-glass is woven into light and heavyweight cloth, each with its benefits. The lightweight E-glass fiberglass cloth has a smoother finish when cured and, when used in combination with a resin, provides excellent waterproofing. Heavier E-glass becomes much more rigid and offers more strength.


S-glass fiberglass cloth is what most would consider "high-performance" fiberglass. This is because the cloth reaches 30% or even 40% more tensile strength than conventional E-glass. Tensile strength is the measurement of stress the material can withstand before breaking.

Other Options

Another option that can often be chosen when designing a fiberglass product is the directionality of the fibers, which can contribute to strength. In some cases, different textiles may be used as well, such as Kevlar and carbon fiber. Finally, different resins may be used, including varieties of polyester resin, vinyl ester, and epoxy resin.

Questions about marine fiberglass or any other fabrication or composite part needs? Reach out to our Painted Rhino team today!