Aspen C108 Review and Ownership Guide

From Glacier Bay to a patented power proa

The Aspen C108 only makes sense once you know who drew it. Larry Graf founded Glacier Bay Catamarans in 1987 and ran it for 20 years, taking small twin-outboard cats on open-water runs to Bermuda, Midway Island and Alaska. He left in 2007 and founded Aspen Power Catamarans in Burlington, Washington, in 2008 around a different idea: a catamaran whose two hulls are identical in profile but very different in plan view, with one hull about 35 percent thinner than the other.

Graf calls it a Power Proa, after the Pacific outrigger canoes with a big hull and a small one, and it is protected by US Patent 8,109,221. Early Aspens such as the C90 and C100 used a single diesel inboard in the fat hull, with the thin hull shaped to cancel the offset thrust and torque so the boat runs straight. The C108 moves the concept to outboards, and it is the model most buyers mean when they search for the Aspen c108 today.

Aspen describes the C108 as its 35 ft model in the lineup, though the boat measures 37 ft 6 in overall with the swim step. It sits between the 32 ft C100 and the 40 ft C120, alongside the newer C110 and the 44 ft C128.

Why a 200 and a 115 share one transom

Look at the transom and the asymmetry stops being hidden. The C108 carries a 200 hp outboard on the wide starboard hull and a 115 hp outboard on the slim port hull. Boating's test boat had a Yamaha F200 and F115 with 1.86 and 2.15 gear ratios, propped proportionately so both engines share the same rpm range. Current boats list Mercury 200 and 115 outboards as standard.

Graf's explanation is simple: the thin hull makes less drag, so it needs less thrust, and matching thrust to drag keeps the boat tracking without a constant helm correction. Boating found the boat ran straight, banked flat turning to starboard and showed a slight outboard lean turning to port. The tester also noted there is no automatic engine sync, so you match rpm by hand, and that the binnacle sits to port of the wheel, which takes some getting used to.

There is a practical upside the spec sheet does not shout about. If one engine fails, either outboard can bring the boat home at displacement speed, and Aspen's earlier C107 test in Boating showed the boat making 7 mph at 1.9 gph on the bigger engine alone.

Boating's numbers, 2.1 mpg and no planing hump

Boating tested the C108 for its March 2021 issue with 72 gallons of fuel and 400 lb of crew. The most economical cruise came at 19 mph (about 16.5 knots) and 3,500 rpm, where the boat returned 2.1 mpg, which works out to roughly 9 gph combined. Top speed was 30.6 mph (about 26.6 knots) at 5,500 rpm, at 0.96 mpg, or roughly 32 gph. Sound levels were 72 dBA at cruise and 81 dBA at wide open throttle with the cabin closed.

The C108 does not plane in the conventional sense. Boating saw very little bow rise anywhere in the range, so there is no hump to climb and no drop in visibility as you accelerate. With the optional 180 gallon tanks, Boating calculated about 340 miles of cruising range at the efficient setting.

Put those figures next to the magazine's comparison boat, a World Cat 400 DC-X on twin Yamaha 425s that reached 43.6 mph but managed only 1 mpg at its best cruise, and the Aspen's case is obvious. It is not fast. It is cheap to move, and it carries real cruising accommodation that a dual-console cat does not.

Trailerable at 37 ft, with conditions

Aspen kept the C108 under 40 ft overall and quotes a combined boat and aluminum trailer weight of about 12,500 lb, light enough for a standard three-quarter ton pickup. That makes it unusual: a full cruising cabin with a king berth that a snowbird can tow from Puget Sound to Florida, or haul home for winter storage in the driveway.

Be realistic about the beam. At 10 ft 8 in the C108 is wider than the 8 ft 6 in most US states allow without an oversize permit, so long tows mean permits, daylight-only travel rules in some states and possibly escort requirements. Bridge clearance is 8 ft 2 in with the mast down in the water and 12 ft 8 in on the trailer. Aspen's April 2026 options list includes a triple-axle float-on trailer rated for 15,000 lb net.

Teak, a 12 ft galley and a king berth athwartships

Aspen widened the beam to 10 ft 8 in for this model and claims about 30 percent more living space than some earlier Aspens. The saloon has full-height wraparound Solar Gard windows that slide open, a five-person C-shaped dinette with a Burmese teak table, twin Bentley's helm and companion seats, and a long galley with a Force 10 propane stove and oven, microwave, Nova Kool refrigerator and stainless sink. Boating measured 6 ft 5 in of maximum cabin headroom.

Down a passage on the starboard side, the master in the bow has an elevated king berth that sleeps athwartships, a hanging locker and two overhead hatches. Aft of it, the head compartment has more than 6 ft of headroom, a shower and a second door into a midcabin berth. The price sheet also lists quarter berths port and starboard. The aft bulkhead window hinges up to open the cabin to the cockpit, which is the best feature on a warm evening.

Joinery is the brand's calling card. Walnut is standard and teak is optional, with an ash inlay, and the build quality on the boats we have seen is closer to a semi-custom yard than to a production builder.

Systems built for anchoring out

The standard spec reads like a Pacific Northwest cruising checklist: a Side-Power bow thruster, Lewmar windlass with deck and helm controls, two 6 volt house batteries plus a start battery, a 360 watt solar array with boost charging, a 400 watt inverter, Victron chargers, eight automatic bilge pumps (one per compartment), double-bottom hulls with collision bulkheads and 30 amp shore power.

Most buyers add to it. The 2026 options list includes a 600 amp-hour Victron lithium package, larger inverter chargers, a 17,000 BTU air conditioner, Wallas diesel or Propex propane forced-air heat, a stern thruster, an electric tender davit and a Starlink mount. Budget at least $60,000 to $100,000 of options on a new boat if you plan to cruise for weeks at a time.

• Standard fuel 130 gallons in three tanks; 180 gallons optional
• Water 50 gallons; holding 26 to 30 gallons
• Draft about 22 inches with the outboards half tilted
• Cockpit 65 sq ft with sink, mini fridge and cooler

What the C108 costs to buy and keep

In 2021 Boating quoted a $398,000 base price. Aspen's April 2026 price sheet lists $634,100 with standard equipment, and options are priced individually, from $200 for a cooling fan to five-figure electrical and comfort upgrades. Local freight and launch are included, while trailer delivery and longer freight are quoted separately.

Running costs are modest for a 37 ft cruiser. Two outboards are cheaper to service and replace than diesels, there is no shaft, strut or bottom-mounted running gear to maintain, and at 9 gph cruise the fuel bill stays low. We estimate $18,000 to $38,000 a year including moorage, insurance, outboard service, bottom paint and a repower reserve. Trailer owners who store at home can come in well below that.

Used C108s rarely come up, and when they do they tend to sell through owner networks and Aspen itself. Low hours, the 180 gallon tank option, lithium power and a trailer are what buyers pay for.