The C120 mixes an efficient ride with comfortable accommodations.

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Aspen Power Catamarans employ asymmetrical hulls similar to Polynesian proas. These provide stability, seaworthiness, extraordinary efficiency and generous interior space for cruising accommodations. The C120, Aspen’s largest model, features a single Volvo Penta D6 diesel driving a conventional inboard prop shaft at a low, efficient angle. A shallow keel protects the propeller and rudder. Bow and stern thrusters aid maneuverability.

Both hulls of an Aspen are narrow enough for their length to beat the speed limitations of displacement hulls. Our test boat hit a top speed of 22.9 mph. High cruise is an impressive 17.2 mph, while low cruise is 9.1 mph at 4.4 gph, good for passage-making at trawler speed, with enough extra on tap to run ahead of a storm.

The genius lies in the fact that the port hull is 35 percent narrower than the starboard, and its actual drag is approximately 50 percent less because it has no keel, shaft, rudder or propeller. The single-engine design also saves machinery weight, which in turn eliminates the need for additional structural components and fuel. These savings reduce the boat’s weight approximately 40 percent, with corresponding efficiency gains.

The configuration also offers comfortable living space, with a bright, airy pilothouse/salon with a full galley and dinette. The helm includes multiscreen Garmin electronics and seating for two. An optional Aspen Adventure Electronics Package ($43,658) hints at the C120’s designed long-range cruising mission.

Forward, a queen-size berth offers standing headroom on each side. Amidships, there’s a full head with a shower in each hull. Aft, there’s a queen berth in the starboard hull and a single in the port hull. The shaded cockpit offers seating and a teak table. Hatches provide access to the engine and 6 kW Kohler genset. A broad transom platform mounts an ingenious dual-winch system for carrying an 11-foot RIB with a 20 hp outboard. The flybridge offers a second helm, seating for eight, a drawer refrigerator, and a polished teak table with a compass rose inlay.

Engine: Single 435 hp Volvo Penta D6

Drive/Prop: Inboard/23″ x 20″ 4-blade bronze

Gear Ratio: 2:00:1 Fuel Load: 55 gal. Water Load: 80 gal. Waste Load: 15 gal. Crew Weight: 760 lb.

There’s no other proa cats that we know of, but check out the Fountain Pajot MY4.S ($827,867 with twin 250 hp engines). Its two hulls are similar, with twin diesel inboard engines of 150 or 250 hp. It offers redundant safety and is faster at wide-open throttle, at about 25 mph. But it can’t match the Aspen’s range and efficiency.

Aspen Power Catamarans – Burlington, Washington; 360-668-4347; aspenpowercatamarans.com

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