In shopping for a multihull, you review and compare the plans offered by numerous designers trying to sort out which of these boats will best suit your needs. Jim Brown, one of the modern multihull pioneers, wrote this piece to help you understand the advantages of a Searunner trimaran over other multihulls.



Who Do I Believe?

As you shop for a new multihull, you ask yourself these questions, "Who makes the best cruising multihull? Which designer can offer me the best boat for my needs? All of them tell me their boat is the BEST. Who do I believe?"

You can only believe yourself in this matter. The best boat is the one that’s best for you.

It’s as simple as that. Searunner trimarans should be given your highest consideration in making your “What’s best for me?” decision.

Jim Brown, designer of Searunner trimarans along with co-designer John Marples, has been part of multihull design and development since the early days of the modern multihull. Jim, an extremely talented designer applies his deep seated love and understanding of both traditional vessels and multihulls by bringing together features from successful world cruisers, combining them to create his Searunner trimarans. These unique features are: the centerboard, the central cockpit, cutter rig, the interior, and the hull form and its construction.


A retractable fin keel that, when retracted, yields a shallow, beachable boat, but when extended serves many purposes. The centerboard is “down there”, always hanging on, performing its primary function of lateral resistance. It also serves to dampen the pitching motion and roll of a boat under way, reaching down into deep, quiet water. Float fins or daggers can’t do this because they are jumping in and out of disturbed water and are, at best, marginally effective. Off the wind the board keep the boat from sliding sideways (broaching) and lets the rudder perform its job of control. To make the board big enough and strong enough to do a really good job demands a large trunk, so Searunners put this trunk in the center of the boat. That’s okay because the central cockpit goes on top of this trunk.

Central Cockpit

The central cockpit gets the helm up there where the helmsperson can see, not huddled down in the back of the boat, exposed to boarding seas and uncomfortable motion, due to centralized weight distribution. Tankage and heavy stores go where they belong: in the center of the boat, next to the center-board trunk and under the cockpit. And, if you have an inboard engine, it goes there too. All this should be enough, but combine the central cockpit with the cutter rig and now, you’ve really got something. The mast is in the cockpit too, easily accessible for both helmsperson and crew!

Cutter Rig

In a cutter rig the mast is stepped further aft than a sloop, almost to the center of the boat. In Searunners, the mast steps on top of the centerboard trunk, taking advantage of its inherent strength. This gets the mast off the akas (cross-arms), allowing them to be lighter. The larger fore-triangle allows Searunners to carry both a headsail and a staysail, permitting sail adjustments to be made without leaving the cockpit. Add the strength of double spreaders and running backstays and the result is that Searunners give you the most rugged rig available in modern cruising designs.


Searunner interiors offer privacy by having the central cockpit separates the two sleeping cabins. Nobody is cooking in your sleeping area because space is allowed for that too. Head compartments include shower facilities and ample stowage. Stowage space is designed to fit the needs of the serious cruiser, with many nooks and crannies so that your gear can be stowed near the area where it is used. Heavy stores are kept under the floor boards or in the large lockers under the cockpit. All this adds up to comfort, both while underway and in harbor.

Hull Form and Construction

The main hull of Searunners has a fine entry to relieve wave-making, a chesty forebody for buoyancy forward, a nearly semi-circular midsection and a broad, flat outrun to minimize pitching. The result is a good compromise giving both speed and stamina. The amas (floats) must operate with a variable waterline, just skimming the surface when running down wind but being burdened by the heeling effort of the sails when sailing to weather. If they had broad transom like the main hull they would drag a chunk of water behind them while depressed, but Searunner amas have fine entries and fine exits.

Construction is of sheet plywood rather than molded plywood. This makes possible widely spaced frames which in turn make possible the easy installation of the Searunner Interior. A molded chine greatly simplify the installation of plywood planking, and the removal of the mast from the cross-arms enables Searunners to replace the akas with main strength bulkheads. Because these lighter, simpler main strength bulkheads are relieved of mast stress, it is possible to allow large, cut out doorways through them, meaning the crew doesn’t have to duck under beams.

With the design criteria established the next most logical question is:

Can I Build it Myself?

And if so … How?

By taking matters into your own hands, that’s how. Yes, you can build your own seafaring sailboat if you know exactly what to do. If it’s a Searunner trimaran you are building, the plans and the Searunner Construction manual tell you how, exactly.

For some, a mere suggestion of how to build a boat—terse notes inscribed on the building plans—is all that is required. Others want basic guidance every step of the way. Building and outfitting any cruising boat has certain oceanic aspects, and the neophyte builder is very often an uninitiated oceanaut…he needs instructions which relate the building to the sailing! The plans hold the two together. They say, “Build it like this, because using it is going to be like…that.”

The individual’s backyard project is divided into five phases, and each phase starts right at the beginning. It’s assumed that you may have built a birdhouse, but never a boat.

Phase I. To Build the Hulls, begins by describing the needs of the worksite, proceeds through selecting tools and procuring materials—and then you start building. The exact process of framing-up and planking a Searunner is given—step by step—with detailed illustrations for each, literally holding your hand and prodding you with encouragement.

Phase II. Fiberglass tells the whole story of a special method for covering wooden hulls—a system which has been shown to give long-lasting protection and require minimum maintenance. To use this method, the builder must understand the requirements of fiberglass—its basic component materials, special tools of the trade, and the nature of surface preparation. These plans give that understanding. Fiberglas is perhaps the most foreign of all materials to the beginning boat builder. This is hard, messy work with great portent for frustration. However, if the builder is armed with a dozen little hints, like how to handle the cloth, how to catalyze the resin, how to take advantage of changing climatic conditions, and how to make use of different degrees of hardness while sanding—these will all combine to minimize the work, the mess and the frustration. Most important of all, these instructions tell you what not to do, as well as how to do it right.

Phase III. Wings, Decks and Superstructure, starts by describing the rather tricky business of joining together the hulls of a multihull. To position and align the hulls, and install the wing framing, is handled with a careful step-by-step approach. Then the myriad details of deck framing and superstructure are given. These details provide, in advance, for all the openings like: companionway hatches, deck hatches, wet-lockers, life raft stowage, propane bottle compartments, windows, ports and ventilators. Close-up photographs are used to illustrate the details of a total decking system which prepares for many features on the inside, so that deck hardware can be easily installed later from the outside: like winch bases, mooring cleat doublers, chainplates backups and hatch hardware attachments. A broad discussion of interior and exterior painting is included.

Phase IV. Interiors starts with the installation of your auxiliary engine: “more than any other kind of engine, a boat’s engine is lived with—day in and day out”. Such matters as the engine bed, shaft alignment, propeller sizes, engine room ventilation, vibration damping, exhaust systems, engine plumbing, wiring and controls are all considered form the standpoint of owner installations. Outboard motor versus inboard engine, gas versus diesel, and engine versus no engine, ... these subjects are addressed in a manner to qualify the reader enough to make his own decisions.

Going on to furnishings, there is emphasis on the single most important space in the interior—the galley. And the second most important space—the head. Dinette design, stowage arrangements, bunk spaces, carpets, headliners, upholstery, plumbing, wiring, ventilation and safetyin the interiors are topics which receive straight-talking, build-your-own type explanations, with illustrated examples from Searunner interiors.

Phase V. Outfitting, asks if you have thought about building your own hollow spruce mast? The plans tell how. Or would you prefer to build-up you own aluminum spar from a bare extrusion? The plans compare these two alternatives and give you enough information to decide which to build, and how to accomplish both. Spar hardware, booms, goosenecks, rigging, chainplates, spinnaker poles, winches, deck hardware, lifelines, pulpits,.... It takes a lot of savvy to do your own, and these plans will guide you through, even if you’ve never done your own before.

Sails, centerboards, rudders, self-steering—it’s all there in detail for Searunners, and Searunner details have already been applied to many different boats.

The equipment list contains descriptions of such things as life rafts, dinghies, man-overboard poles, anchors, navigation materials, even spare parts. And there is a separate appendix with sailplans and specifications for each Searunner design. There are also sections on building for economy and using epoxy.

Searunner Plans and Searunner Construction answer the question “Can I build it myself?” You can build your own multihull. And once you’ve built your own ocean-cruiser you’ll know, "There is nothing on the earth more satisfying than running the sea in a boat you have built yourself."