Fiberglass (GRP)

Glass-fiber cloth laid up in resin inside a female mold, perhaps the most common way production boats are built.^1,2

Hulls on record: 8
Builders: 1
Built between: 2013–2026

On the recordHulls by decade built

42010sViking
42020sViking

First on record: PanaceaViking hull 82-019 · 2013
Latest on record: HoorayViking hull 82-210 · 2026

What it is

Fiberglass is fiber-reinforced plastic: layers of glass cloth bonded with polyester, vinylester or epoxy resin. It caught on in the 1960s and is now perhaps the most common way production boats are built.¹

It came into its own on lower production costs. In sportfishing, the Hatteras name went on to dominate the fiberglass market for decades.^3,4

How it's built

Most production hulls are laid up in a female mold. A release agent goes on first, then gelcoat, the glossy outer finish, 12 to 22 mils thick. Alternating layers of glass cloth and catalyzed resin follow to build the laminate.^1,2

A core of balsa, marine plywood or foam can add strength without more heavy glass, typically in the transom, topsides or deck. Even a solid-glass hull relies on stringers and bulkheads to keep the laminate from flexing.^1,2

What it's good for

Fiberglass is relatively low in maintenance, high in strength and easy to repair, and it generally costs less than other boatbuilding materials.¹

Trade-offs

Polyester resins and gelcoats are not waterproof. Water migrates through them, and some hulls suffer osmotic blistering. A 1990 Practical Sailor survey suggested one in four boats would blister in its lifetime.^1,2

Unless combined with composite materials, a fiberglass hull can run heavy.¹