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2021 Aspen C108

A proa-style power catamaran boasting asymmetrical hulls and a unique pairing of outboards.

February 10, 2021
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Aspen C108 cruising through the bay
With an asymmetrical hull design and accommodations for extended cruising, Aspen’s C108 begs you to set a course for new horizons. Courtesy Aspen Power Catamarans

Overview

Asymmetry rarely exists in boat hulls, but there are exceptions, including the outrigger canoe and the Pacific proa. Both of these have two parallel hulls, but one hull is thinner than the other. These helped inspire a unique line of boats—Aspen Power Catamarans. Company founder and president Larry Graf has long stood as an advocate of catamarans, but Aspen takes this hydrodynamic concept to a new level with an asymmetric design. With its asymmetrical hulls, efficiency and intelligent accommodations for extended cruising, Aspen’s C108 begs you to set a course for new horizons.

Engines

An Aspen’s starboard hull is wider than its port hull. The thinner hull generates less drag. At the same time, each hull offers a balance between displacement and load, and that keeps the boat stable. The asymmetry goes largely hidden, except for one obvious element.

While early Aspen models featured a single diesel inboard within the larger of the two hulls, newer models, including the C108, are propelled by two outboards. Here’s where the asymmetry becomes readily apparent because the outboards are not identical. On our test boat, for example, the starboard engine was a Yamaha F200, but the port outboard was an F115. Both engines share the same rpm range, and each is propped proportionately.

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Aspen C108 running comfortably
The C108 makes for a great overnight cruiser. Courtesy Aspen Power Catamarans

“Because the port hull creates less drag, it does not require as much power as the starboard hull,” Graf explains. “This combination of horsepower offers the best of both worlds in terms of tracking, speed and efficiency.” Indeed, the C108 runs straight while underway. It banks flat when turning to starboard, but we observed a slight outboard lean when turning to port. Most economical cruising speed occurred at 19 mph and 3,500 rpm, where the C108 achieved 2.1 mpg. We recorded a top speed of 30.6 mph at 5,500 rpm, where the C108 posted 0.96 mpg. The boat does not plane, so there is little bow rise throughout its displacement speed range.

How does that compare with other cats? The World Cat 400 DC-X ($848,943 as tested in our October 2019 issue with twin Yamaha 425 XTO outboards) achieved a top speed of 43.6 mph at 6,100 rpm with 2.7 times the horsepower. Best cruising efficiency was 21.3 mph, where the World Cat posted 1 mpg. Also, this World Cat is a dual console, and while about 2 feet longer, it hardly approaches the Aspen’s cruising accommodations.

Interior and Accessories

The C108 begs to venture far and wide, with an enclosed cabin featuring an aft companionway to port and a special aft bulkhead to starboard—the top half hinges and locks upward to open the cabin quarters. Solar Guard windows flank the cabin to reflect 50 percent of the sun’s UV energy, but the glass and screens can slide open to allow a breeze. Four Lewmar hatches in the cabin usher in light and fresh air from above.

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Aspen C108 helm
The helm is outfitted with two Garmin multifunction displays, a ­Garmin autopilot display, and controls for the standard bow thruster. Courtesy Aspen Power Catamarans

A convertible nook-style dinette with a Burmese teak table occupies the starboard-side, while a Corian-topped galley counter with a sink and faucet, propane cooktop/oven, fridge and teak cabinets line the port side. Grab rails provide handholds and keep items from sliding off. There’s also a passageway aft to a cozy berth within the port hull. Amtico decking offers the look of wood, without the warping or stains.

The helm resides forward on the port side, with an adjustable Bentley’s captain’s chair. Exquisitely crafted teak forms the instrument panel that accommodates two Garmin multifunction displays, a Garmin autopilot display, and controls for the standard bow thruster and optional stern thruster, among other controls and displays. SeaStar Optima power steering reigns in the two outboards. In an unorthodox setup, the binnacle control for the outboards is on the port side of the wheel. Opposite the helm is another Bentley’s chair. A full-width glass windshield, equipped with a pair of wipers, offers an expansive forward view. With the cabin closed, sound levels while underway are exceedingly low. We recorded just 72 dbA at optimum cruise, and only 81 decibels at wide-open throttle.

Aspen C108 dinette
A convertible nook-style dinette with a Burmese teak table occupies the starboard-side. Courtesy Aspen Power Catamarans

A descending passageway on the starboard-side accesses the master stateroom in the bow, with an elevated king berth, hanging locker, teak accents, and a pair of Lewmar hatches overhead. Access to the immaculate helm rigging is outstanding thanks to a removable panel in the bulkhead abaft the berth. Step aft to find the head compartment, replete with more than 6 feet of headroom, a shower, flushing toilet, sink, vanity and mirror. Keep walking aft, through the second door of the head compartment, to find a midcabin berth.

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Aspen C108 galley
A propane cooktop/oven combo is located to port. Courtesy Aspen Power Catamarans

The cabin top extends aft over the cockpit to provide shade while fishing or crabbing. There’s a sink and faucet to wash up. A surprisingly spacious platform between the motors, accessed via a starboard transom door, allows for easy snorkeling or scuba diving. The C108 comes with a 96-quart cooler for the cockpit, and you can order a rack to stow an inflatable dinghy above the outboards and roof racks for kayaks. A stainless-steel rail along the catwalks and bow ensure safety when going forward to man the anchor windlass.

Aspen C108 master stateroom
The master stateroom is equipped with an elevated king berth. Courtesy Aspen Power Catamarans

If you’re a boater intent on exploring fresh destinations with no rush to get home, Aspen’s C108 may well be your ticket to adventure.

How We Tested

  • Engines: Two Yamaha outboards (F200 starboard and F115 port)
  • Drive/Prop: Outboard/14.5″ x 13″ (starboard), 13.125″ x 16″ (port) 3-blade stainless steel
  • Gear Ratio: 1.86:1 (F200), 2.15:1 (F115) Fuel Load: 72 gal. Crew Weight: 400 lb.

High Points

  • Overnight accommodations for five or more render the C108 a great cruiser.
  • Optional 180-gallon fuel tanks offer 340 miles of cruising range based on our testing.
  • A 360-degree view from the cabin helps you stay aware of your surroundings.

Low Points

  • Throttle-and-shift controls to the left of the wheel take some getting used to.
  • With a top speed of about 30 mph, this boat is not for speed demons.
  • No auto-syncing of engine rpm, so you need to do it the old-school way.

Toughest Competitor

How does that compare with other cats? The World Cat 400 DC-X ($848,943 as tested in October 2019 with twin Yamaha 425 XTO outboards) achieved a top speed of 43.6 mph at 6,100 rpm with 2.7 times the horsepower. Best cruising efficiency was 21.3 mph, where the World Cat posted 1 mpg. Also, this World Cat is a dual console, and while about 2 feet longer, it hardly approaches the Aspen’s cruising accommodations.

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Pricing and Specs

Price: $398,000 (base with Yamaha F200 starboard and F115 port)
LOA: 37′6″
Beam: 10′8″
Draft: 2′2″
Displacement: 10,840 lb. (with test power)
Transom Deadrise: NA
Bridge Clearance: 8′2″ (mast down)
Fuel Capacity: 130 gal. (standard); 180 gal. (optional)
Max Cabin Headroom: 6′5″
Max Horsepower: 315
Available Power: Two Yamaha outboards (F200 starboard and F115 port)

Speed, Operation, Efficiency

Aspen C108 performance data chart
Aspen C108 Certified Test Results Boating Magazine

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

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