How sailboats are made

A production sailboat gets its whole interior before its deck, which then drops on like a lid.

stations: 11
things upstream: 69
raw sources: 21
steps from the ground: 8

The short version

Most production sailboats are fiberglass hulls laminated inside a polished mold, starting with a skin of gel coat. A stiffening grid goes in, then engine, plumbing and prefabricated cabins. The separately molded deck is bonded and bolted on top, a cast keel is bolted beneath, and the boat is water tested. Mast and sails often go on at the dealer.

Spray the gel coat

Layers of gel coat are sprayed into a clean, highly polished mold to form the outer skin. Dufour's molds come in two parts and sit on rollers, so workers can rotate them in place.

Goes in
Polyester
Laminate the shell

Glass cloth and core materials go in by hand and are soaked with resin, layer by layer. Hunter's hull is solid below the waterline and balsa-cored above it. Vacuum infusion and injection are the alternatives.

Goes in
Fiberglass Polyester
Thicken the loaded areas

Workers add extra laminate at the chainplates and around the keel, where the rig and ballast pull hardest.

Goes in
Fiberglass
Bond in the grid

A molded fiberglass grid is chemically bonded into the fresh hull to give it stiffness. Hunter builds interior units onto this grid first, then lowers the lot in together.

Goes in
Adhesive
Infuse the top half

Dry glass mats go into a separate mold under a plastic cover. Air is sucked out at one end and resin drawn in at the other, which pulls it through the mats and leaves a stiff, thin deck.

Goes in
Fiberglass Polyester
Install the systems

The empty hull rolls to the fitting hall. Engine, tanks and steering usually go first, then plumbing and wiring.
Drop in the cabins

Series builders assemble bathrooms, cabins and saloons outside the boat, already wired. Each module is hauled in and glued, screwed or laminated into place.

Goes in
Adhesive
Marry hull and deck

Once the interior is in, the deck goes on top, closing the boat. The joint is usually high-strength glue plus screws or bolts.

Goes in
Adhesive
Bolt on the keel

A keel of cast iron or lead is lined up exactly with the centerline and fixed to the underside with keel bolts. Cast iron is heavy and cheap, while lead is denser.

Goes in
Lead Pig iron
Test for leaks

In a pool or a station like an oversized carwash, the boat floats for the first time and takes hours of artificial rain, so inspectors can find leaks at hatches and portholes.
Rig the mast

Dealers at big brands often step the aluminum mast, attach the wire rigging, and install sails of synthetic cloth such as Dacron.

Goes in
Aluminum Wire rope Polyester

End of the lineSailboat

Worth repeating

Monohull sailboats generally rely on ballast for stability, and in racing boats the ballast can be a large part of the weight.
Multihull sailboats rely on the geometry and broad stance of their hulls for stability and carry no ballast.
A prefabricated bathroom can be fitted into a yacht in just a few hours if the installation goes well, according to the builder Hanse.