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June Edition 2023

Antrim Associates Naval Architects: Designing ultimate and diligent sailboats which offers great buoyancy and performance


Naval architecture, the art and science of designing boats and ships to perform the missions and to meet the requirements lay down by the prospective owners and operators. It involves knowledge of mechanics, hydrostatics, hydrodynamics, steady and unsteady body motion, strength of materials, and design of structures. A good naval architect and ship designer must have experience in a number of fields of engineering, as well as in the field of engineering economics. The architect must also understand the characteristics and properties of construction materials and be familiar with the latest and best methods of fabricating parts and joining them. Like other branches of engineering, naval architecture involves estimates and predictions of the final performance of the ship and all its parts, and of initial and operating costs. Such calculations must be made while the ship is still in the paper stage in the form of plans and specifications.

By all accounts, Jim Antrim is one of the more thoughtful and diligent designers in the business. A long time Bay Area favorite, Jim's Antrim 27 is what has put him on the map nationally. Like many of the "independent" designers, Jim is busy with a number of projects, not the least of which is in the multihull arena. If there is one area that separates Jim from some others it is here. His 40' tri "Aotea" launched in 1990, helped establish Jim as a serious threat in this seemingly strange (at least to monohull sailors) world. He founded Antrim Associates Naval Architects in 1979.

Design Services

These are questions that 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. Antrim Associates makes 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. Their 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 they 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.

Antrim Assoaciates' Monohulls

The monohulls range from the rugged ocean racing Open 50 ‘Everest Horizontal’ to the exciting buoy racing Ultimate 20. All of their monohulls feature deep bulb keels which give way to generous sail plans. A small, low overlap jib can be found on their production sport boats, making the use of a winch virtually nonexistent. All use the latest com- posited 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. Their 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 their multihulls. Their trimarans feature high buoyancy and planning 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. The 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. Their 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 the trimarans.

All of their 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. Multihulls enjoy other, less obvious, light air advantages. These days, most multihulls today have a fully battened main. These are great for holding the sail steady. Anyone who has slatted about for more than 5 minutes can appreciate the enormous speed (not to mention sanity enhancing) advantage of this feature. And, if I may be permitted a bit of promotion, wing masts and boomless mains are great in these conditions. The wing mast is efficient: low drag and smooth flow over the main. A boom in light air is like hanging a 3 pound salmon ball on your spinnaker clew. All it does is make the leech too tight and fling the sail about.

Jim Antrim | Owner

A graduate of Webb Institute of Naval Architecture, Jim Antrim founded Antrim Associates in 1979 after apprenticing with leading naval architects Dick Carter, Britton Chance and Gary Mull. His design portfolio is one of the most diverse in the industry, and includes record-breaking custom multihull and monohull sailboats, popular production boats, wing-sail assisted motor-catamarans, and recently, a solar-powered unmanned electric craft.

Jim has developed several computer programs used in laminate engineering analysis, as well as performance analysis and prediction. His services are often sought after by other leading naval architecture firms. His love for the sport of sailing ensures thoughtful, fun and leading edge designs

"People come to us because they are looking for innovation and personal attention. We work hard to make sure they will get the most enjoyment out of their boat."