The WHITACRE 47 four-season, liveaboard catamaran is a game-changer.
It’s a massive departure from the typical warm-weather, mass-market charter boat, with an affordable semi-custom design, and a unique, energy-efficient power system.
At Whitacre Yacht Design, we believe that a growing number of sailors are searching for a more customized approach to their multi-hull experiences — but one that doesn’t break the bank.
Our market model is simple – we offer a semi-custom, performance, offshore catamaran to discerning multi-hull sailors who want it their way.
We developed the WHITACRE 47 after we evaluated the increasing complexity of high-tech performance/cruising catamarans on the market. It was clear that simpler operations for an owner-operated performance/cruising catamaran were missing from current builds.
The higher-tech also adds cost, complexity, and weight. And when that more complex tech fails, sailing is off the table.
Most available 45’-50’ cruising cats are over-outfitted with tech and amenities for charter builds which essentially strips them of the “performance/cruising” label.
To put the “performance” back into “performance/cruising,” and make it accessible to owner-operators who want to cruise year-round, we designed the simple, lightweight, reduced-tech WHITACRE 47.
While weight can be the natural enemy of performance, the greater enemy is a hull designed to meet unrealistically low weight claims that won’t support real-world uses.
Too-low boat weight projections result in a larger wetted surface, reduced bridge deck clearance, and overloaded rigging.
WHITACRE YACHT DESIGN believes in projecting realistic build weights and designing the hull around them.
While competitors’ “sailing weights” sound great, they don’t account for the “stuff” we all bring on board; clothes, diving equipment, pots and pans, and furniture.
Our boat is a liveaboard. So we use real weight projections, for real cruisers.
The WHITACRE 47 hull form is designed with the tweaks we glean from constantly re-evaluating the cats we work on.
The bow form is fine in terms of waterline shape, but in a cross-section view, you see a gentle parabola to give the bows dynamic lift when you’re running down a swell. This allows the hulls to penetrate waves at relatively low speed. As speeds increase, usually accompanied by increased vertical motion, lift in the bow is dynamically generated – keeping the bow on top of the water, rather than plunging.
The aft hulls are less circular/parabolic, to boost buoyancy there, and keep aft trim down. Current sailing catamarans tend to accumulate weight aft, but what they actually need is more buoyancy aft, to lift the weight of the propulsion system and fuel, so you’re not displacing water, but planing across it.
Another unique feature in the aft sections of the WHITACRE 47 is a slight chine that prevents water from running up the sides of the hull at higher speeds. It is not intended to achieve full water separation in this area, but to help it along. It also boosts underwater volume and buoyancy aft, while providing a bit more dynamic dampening of the hulls in pitch.
In short, hull length-to-beam ratio is based on actual volume/displacement – not an unrealistic goal set at the outset of the boat’s design simply because it sounds good.
Deck arrangement and layout of the WHITACRE 47 is heavily influenced by experience with forward-inside helm stations popular with Gunboats, HH, and similar vessels.
That design generally results in a spaghetti factory of lines surrounding the helm station, whether inside or outside. And the space required to accommodate a forward cockpit is too great to be accommodated in a 47-foot boat.
Instead, the WHITACRE 47 uses dual aft helms, to which the mainsheet, traveler, and solent or genoa sheet are led. The dual helm allows the helmsman to work from one side of the boat, out of the way of sheeting activities, or on the other side, when single-handing. Halyards and reefing are forward, up at the mast.
We also know from experience that it is possible to reef and hoist sails from inside the cabin area. But it usually requires a second person at the mast to spot the maneuver. On the WHITACRE 47, mast-mounted winches allow one person, in one spot, to do it all.
All winches are intended to be non-powered, to reduce weight and electrical load.
The machinery outfit on the WHITACRE 47 is customizable, ranging from a traditional diesel auxiliary propulsion system to a hybrid diesel-electric propulsion system.
A diesel auxiliary propulsion system would be best with 2x 40+ hp marine diesels connected to saildrive units. A small generator would usually also be required. But high-output alternators, combined with available solar power and a reasonable electrical load could eliminate the need for a generator.
An alternative to the traditional diesel auxiliary propulsion is an available hybrid system, with a diesel engine on one side of the boat and an electric motor on the other.
This system is being fitted to Hull #1. It will use robust solar-based electricity for lower speeds and low range, and the gotta-get-there diesel for longer and perhaps higher-speed passages under power.
WHITACRE 47 is designed to be a performance cruising catamaran that can be handled safely by just one or two persons.
She is designed to be quick, but more performance would require a sailplan that not only requires more crew, but reduces safety margins when she is used as an offshore cruiser.
We had to find the sweet spot.
WHITACRE 47 mast and boom are made of aluminum, and engineered to meet or exceed both the CE and DNV GL standards for rig construction. Aluminum significantly reduces the cost of the rig, but without any significant reduction in performance in a catamaran configuration.
Standing rigging is intended to be stainless steel compact-strand wire rope, with lower shrouds of Dyneema or Aramid rope, for both low-stretch properties and cost-effectiveness.
We can customize the mainsail with either pin-headed or square-head full-battened configuration. We suggest three reefs and a low-friction luff system, such as a Harken track or Tides Marine systems.
The headsails are intended to be a self-tending, non-overlapping jib or solent. Flying sails are also customizable, and could range from tight-luffed reaching Code-type sails, to loose downwind asymmetric spinnakers.
Whitacre Yacht Design developed our own bowsprit system. It is mounted to the crossbeam and contains the jammers for the sail tacklines. The system is considerably simpler and lighter than a full-length longeron but retains almost the same protrusion forward of your bows as a longeron.
We also engineered our mast to accommodate sail loads bio halyard locks, to reduce cost, and to keep sails from jamming aloft.
The rig and sailplan of WHITACRE 47 could certainly be both more complicated and more powerful, but that would negate the intention of the boat’s entire concept, of owner-operated simplicity.
The WHITACRE 47 is designed for extended cruising and life aboard.
The helm is located aft, out of the way of main-deck living space.
The galley is starboard, and includes an island for work space, storage, and even a TV. The port main deck can be outfitted with stand-alone furniture or a built-in settee. Finishes, including decks, are customizable.
The main deck is enclosed, with hard frames and weathertight doors aft. Three large skylights provide ample natural light.
The “garage door” aft and on the centerline drops down to a swim deck, and up to open the living space to the sun and sky. Below-deck accommodations are accessed through dual companionways from the main deck.
Living quarters are customizable, but the owner’s cabin utilizes the entire port hull. A queen-sized berth is aft of the companionway, with a head and shower forward.
Inboard of the head, in the cross structure, you can opt for a locker or for generator space, depending on the machinery outfit you choose. Forward of the shower is a sail locker, accessible from the deck and through the shower area.
The starboard hull can be customized to include a queen berth in the cross structure, and an additional queen or two single-berths aft of the companionway. A head and shower are forward of the cross structure. Alternatively, the aft companionway can be an office or workshop.
Interior materials are entirely up to you, but simple and lightweight work best in a performance cruiser.
The WHITACRE 47 is intended to be a cost-effective, customizable, performance-oriented cruising catamaran.
Her hulls, bulkheads, and decks are primarily fiberglass reinforced plastic (FRP) with E-glass cloth and epoxy resin.
We also added modulus carbon fiber, for increased strength and stiffness without added weight, and we did it where it matters — in wet deck transverse frames, the mast bulkhead, and around the aft “garage” door.
The boat is fully cored with high ductility SAN-type foam. These core materials are hydrophobic and prevent laminate failure. There is no wood present to absorb water and take on weight in the unlikely event there is laminate failure.
We also use a vacuum-bag cure process to compress the sandwiched laminate structure, and eliminate excess epoxy resin and air bubbles, for a strong, lightweight composite.
Epoxy resins are more expensive but, in this case, you really do get what you pay for: Greater-strength composite panels and low-VOC, for the most eco-friendly manufacturing environment.
Once the resin/laminate matrix completes its initial cure, the entire hull is heat-cured to improve primary bonding of the laminate skins to the core, and increase strength.
The laminate engineering and specifications are designed to meet or exceed stringent European CE construction requirements.