The Aspen C128’s Mission as a Long-Range Power Catamaran
Aspen power catamarans new flagship 46’ C128 is meant for serious cruising. On her maiden voyage, she traversed the Straits of Juan DeFuca into the open Pacific Ocean for some extensive exploration of the rugged and rarely visited westside of Vancouver Island, Canada. The cruise was a roaring success and the boat performed admirably. But the C128 is not just a cold-water boat—her owners set her up for the Southeast, including larger air conditioning capacity to keep things comfortable while cruising Florida, the Bahamas and further into the Caribbean.
Aspen’s PROA Hull Design Explained
Aspen is known for its patented PROA cat hull design, which maximizes efficiency, provides plenty of usable cabin space and delivers a smooth, stable ride. Unlike other cats that have identical hulls, one of the Aspen’s hulls is one-third hull maintains the buoyancy required to keep the boat running true but requires less energy to move it. The first Aspens were powered by a single diesel inboard, and those models are still available. Next came outboard-powered models, with the size of the outboard matched to each hull, resulting in dissimilar power. The new C128 features two identical motors.
Twin Suzuki 300 Outboards: Power, Redundancy, and Fuel Economy
The C128 has twin Suzuki 300HP outboards with counter rotating propellers. The owners of hull #1 preferred the same motors on both sides. They wanted the redundancy of spare parts and the ability to run on one engine for long periods if needed. While dissimilar motors likely would have produced a slight gain in fuel economy, the hull form itself still makes the C128 more efficient than other similar sized cats.
Aspen founder and chief engineer Larry Graf modified the hull of the popular C120 diesel-powered model, removing the rudder and keel and extending the aft sections, providing additional flotation to compensate for the weight of the large outboards. He also slightly altered the hydrodynamic shape of the hulls for better tracking. Like all Aspens, both hulls have a narrow entry that slices through the water as the boats don’t plane. A unique tunnel design where the forward section can cut through wave tops in heavy seas prevents slapping as the water is cleaved and funnels back through the tunnel before exiting. The Aspen hull form has been widely proven, with multiple vessels going offshore and completing long passages such as the Great Loop. An Aspen C120 even cruised over 10,000 miles including open ocean passages on a journey from Alaska to Annapolis, MD.
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Handling and Maneuverability
The C128 has an LOA of 46’ with a 13’11” beam, so unlike some other catamarans the boat fits in most standard slips. Pinned tightly adjacent a walkway where another boat was moored, Graf had to back straight into the alleyway and then turn the boat in its own radius to get out. The counter-rotating propellers and separation of the engines allow for jockeying the throttles and turning the boat like a twin inboard cruiser. There is a bow thruster, too, in the wider starboard hull, which is carefully angled so its discharge doesn’t reflect off the other hull, but Graf barely used it. He handled the tight maneuvering in the marina, but in clearer waters during testing I was able to spin the boat in both directions on its own axis simply by adjusting the power fore and aft. This is an excellent feature of this boat that makes maneuvering in close quarters much more forgiving.
The helm is comfortable and well laid out with two large windshields, optimizing visibility. Two bucket helm seats are within easy reach of the wheel, throttles, controls, and MFDs arrayed in a large pod. Opening solar guard side windows are a nice touch, as is the additional companion seating to port.
Performance Test
As we began our testing, the twin Suzuki 300hp DF300BMB 4-Stroke/4.4 liter V6 outboards propelled the boat easily. Because Aspens don’t plane, there is no hump to get over; they simply accelerate smoothly and evenly up through the rpm range so you can choose any speed. I used an inclinometer to gauge bow rise, which barely moved and never rose above 2 degrees. The big outboards purred (59-82 db) as we revved up to our peak speed of 30.5 mph and ran 0-20 mph in 9.5 seconds—lively for a boat this size. On reciprocal runs at 20 mph, fuel burn was 21.4 gph, just under a mile per gallon, providing a 252-mile range based on 90 percent of our 300-gallon expedition tank fuel capacity. Slowing down to trawler speeds range increases to 462 miles, meaning you can travel extensively if you are willing to slow down.
We also did a one engine test run, and at 7.9 mph the range using one engine increased to 579 miles—117 miles farther than with both engines at the same speed. Peak speed with one engine was 16 mph. When powered by both engines, the C128, like most outboard-powered boats, likes to go. At 4,500 to 5,000 rpm, she feels rock solid, cruising at 25 mph or more, and still maintains a 200-mile range.
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With dissimilar hulls, you might wonder about turning. I performed high-speed, 26-mph turns in both directions in two to three boat lengths and the boat felt solid, losing only a few mph. She leaned slightly more in the port turn with the thinner hull down, but not excessively, and tracked an ever so slightly tighter circle.
We moved from inside the climate-controlled cabin up the steps to the flybridge to see how she handled from up top. The flybridge has a large u-shaped lounge seating area with a swing-out table and two bucket seats. You can opt for canvas, but the C128 we were on had an optional lightweight (240-lb.) hard top made with carbon fiber. We continued maneuvers from the fresh air of the bridge, where motion can sometimes be exaggerated but the turns felt stable and under control.
Interior Layout, Comfort, and Living Space
In addition to her performance, the C128 features a host of comfortable and useful spaces. The cockpit is large enough to fish, dive or blow up paddleboards, kayaks or other water toys. A RIB or one of Aspen’s Carbon Cat lightweight tenders can be launched, retrieved and stowed from a convenient stainless EZ davit system.
Inside, a large lounge/dinette is adjacent the fully equipped galley, which hosts electric and/or gas appliances, Corian countertops, glass tile backsplash, and elegant walnut cabinetry. There are three private sleeping cabins and two heads: A massive king-sized bed with access from either side is featured in the master stateroom, plus there is a queen VIP and a twin quarter berth cabin.
Shallow-Water Capability for Florida and Bahamas Cruising
The C128 performed flawlessly with her identical outboards. Graf noted that the engineering hours he typically allocates to fine-tune the hulls on new models weren’t necessary. With tiltable outboards and less than 3’ draft, the boat is an ideal cruiser for shallow waters around Florida and the Bahamas. Her narrow bow sections are Kevlar- reinforced and include a watertight collision bulkhead that allows for careful beaching on sandy isles and add protection if you hit coral.
The C128’s performance and efficiency lets owners adventure further and with over 600 square feet of living space and a smooth ride they can remain comfortable as they cruise.
If you hear the purr of a couple of Suzuki outboards, keep your eye out for the big cat on the prowl—the new Aspen C128 to which they are likely attached.
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Full Aspen C128 Specifications
LOA: 46′
Length waterline: 44′
Beam: 13’11”
Max bridge clearance: 14′-17’6″
Draft (estimated.): 2’6″
Cabin headroom: 6’8″
Fuel capacity standard tanks (gasoline): 220 gals.
Fuel capacity w/expedition tanks (gasoline): 300 gals.
Diesel capacity (for generator): 30 gals.
Fresh water capacity: 100 gals.
Holding tank capacity: 80 gals.
Dry weight (est.): 24,000 lbs.
Standard power: Twin 300hp Suzuki 4.4-liter V6
Generator: Kohler 6kw or 9kw (optional for AC upgrade)
Props: 3-blade stainless-steel counter-rotating dual-props
Starting price: $1,356,500
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