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Design Services, How Does it work? What is the process?

These are questions we are often asked by people considering their first custom designed and built boat. The relationship has three phases, commencing with design of the boat, proceeding through the construction process, and continuing after launching.

Conceptual Design often starts with CAD or pencil sketches and ends with an outboard profile or sail plan and preliminary layout. This is the first broad stroke. We make sure the layout you are hoping for fits in the size of boat you want; and that you are happy with the appearance of the boat.

Preliminary Design carries this process further with structural calculations, approximate hull shape, preliminary weight estimates. Our goal here is twofold - to carry the design to a point where builders can give an estimate of cost of construction; and to make sure that the design is feasible from a structural, weight, and performance point of view.

Final Design usually proceeds after a builder is selected and the client has determined that the project is financially feasible. Often the construction process starts before the final design in complete. Obviously we try to stay a couple steps ahead of the builder so that the construction process can proceed smoothly to finally build the boat of your dreams.


Our monohulls range from the rugged ocean racing Open 50 ‘Everest Horizontal’ to the exciting buoy racing Ultimate 20.

All of our monohulls feature deep bulb keels which give way to generous sail plans. A small, low overlap jib can be found on our production sport boats, making the use of a winch virtually nonexistent. All use the latest com- posite building technology to guarantee a solid and stiff boat.

The Antrim 27 is a proven one design and ocean racer, winning back to back Pacific Cups while the Ultimate 20 Class has nearly 200 boats sailing worldwide. Our Open 50 is currently racing around the globe in the Around Alone and plans to compete in the Vendee Globe.

Whether it’s a one-off, or a production monohull racer or cruiser, Antrim Associates has the experience to design a boat that will meet and exceed your expectations.


Easy handling and high performance sailing are features you’ll find in all of our multihulls.

Our trimarans feature high buoyancy and planing geometry which is highly resistant to burying the bow at any speed. Nevertheless, every trimaran will occasionally bury the ama bow. When the ama is submerged, the highly rounded decks will shed water quickly.

Our 30’ tri, Erin, features twin daggerboards in the amas and because they’re canted and asymmetric in cross section, they develop tremendous vertical lift like a hydrofoil.

Our hulls are typically sandwich construction using foam or balsa core. Skins are a composite of carbon fiber, Kevlar, s-glass, and e-glass. Carbon is used in high load areas, and Kevlar in areas vulnerable to impact damage. Amas, daggerboards, rudder, and crossbeams are also composite, heavily carbon reinforced. Wing mast, bowsprit, and rudder posts are essentially all carbon on most of our trimarans.

All of our cruising catamarans feature high bridge deck clearance and retractable daggerboards to provide upwind pointing and reduced drag. Antrim catamarans feature spacious main salons: navigation station, dinette, galley, and lounge. All the comforts of home with a 360 degree view.

Construction is generally triaxial glass over 1" Core-Cell foam, local carbon reinforcement at high stress locations, Kevlar used selectively for impact protection.

Contact Us


4018 Archery Way
El Sobrante, CA 94803

(510) 223-9680