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Aspen Power Catamaran C90
by Roger McAfee
A Traditional Cat in Name Only
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We had no wind and no waves, and the vessel threw so little wake that we couldn`t even do any wake jumping to see how this 28-foot power catamaran handled in rough water. Designer Larry Graf and I were commiserating with each other about how difficult it is to run a significant test in still water... when a Washington state ferry appeared - a big one, motoring right along.
Without hesitation we headed for the ferry wake and ran into it, close to the ferry, at 21 mph. Just before we hit the wake, Graf took his hands off the wheel. The cat sliced cleanly through the wake without fuss or muss - and without any slamming. We crossed the wake on the other side and emerged into flat water. Graf had still not touched the wheel. Our track through the ferry wake was dead straight.
We immediately turned to starboard, took the power off and lay beam on to the coming wake. The cat handled the beam sea easily. We applied the power, ran up alongside the ferry, at a safe distance, turned stern to and took off the power. The wake lifted the stern slightly and passed by easily.
Thus was I introduced to an Aspen power cat. I have no doubt that a 28- foot monohull could have performed the same functions safely - but not as smoothly or as elegantly. A monohull could not have gone through that ferry wake at almost 20 knots without pounding and slamming.
Aspen Power Catamarans of Snohomish, Wash., just north of Seattle, has produced a power catamaran so unique it won a coveted NMMA Innovation Award at the 2009 Miami International Boat Show. The Miami 2009 model was an open boat, but at the 2010 Seattle International Boat show, the builder introduced its cabin version on the same hull - the Aspen C90. So if a 28-foot powerboat that is capable of cruising at almost 18 miles per hour while getting 6.6 miles per gallon is of interest, read on. If you`re happy to take that same boat and move along at trawler or sailboat speeds, about 7 mph, and get about 8.5 miles per gallon, you should read on carefully.
DESIGN AND CONSTRUCTION
Aspen`s Graf is the well-known developer of the original Glacier Bay catamarans. Boaters who follow marine design will remember that in 1988 the Glacier Bay full-scale prototype splashed down. It was a cat with displacement hulls specifically designed not to plane. It weighed 2,200 pounds and made 22 mph on a single 60 hp outboard.
When Graf left Glacier Bay in 2007, he decided to return to his original dream: to produce a non-planing power cat capable of running 20 knots, powered by a single small engine. The new Aspen is a manifestation of that dream. The vessel has a modern yet classy look, and from abeam it`s difficult to tell that it isn`t a monohull.
While the Aspen has twin hulls, it is not a traditional cat. Its port hull carries about 35 percent less beam than the starboard hull; in addition, it carries a 24-gallon water tank and a 40- gallon fuel tank. The starboard hull carries the diesel engine, a 40-gallon fuel tank, a 26-gallon water tank, head/shower and access to the stateroom (with a king-size bed).
Since the starboard hull is volumetrically much bigger than the port hull, it carries the extra weight easily. And because of truly elegant and precise engineering in shaping the two hulls differently, Graf has been able to negate the logical tendency for the boat to veer to port because all the prop thrust is being applied on the stern starboard corner.
The basic hull and other glass components are produced for Aspen by Burlington, Wash.-based Nordic Tugs, one of the Pacific Northwest`s premier builders, known worldwide for the quality of its construction. The components are then transported to Aspen`s shop for completion.
ON DECK AND INSIDE
Access to the vessel is gained from the swim grid through a transom door onto an aft deck big enough to handle four deck chairs comfortably. It is also large enough to satisfy even the most ardent fishermen. Access to the substantial foredeck is along port and starboard sidedecks, and security is provided by higher-than-normal stainless handrails fixed to the coaming and stainless grabrails fixed to the cabin roof. The cabin top also carries the solar panels that help keep the house batteries topped off, and it extends aft of the cabin`s rear bulkhead so rain will not pelt into the cabin when the door is open.
Access to the interior is through a watertight, metal-framed glass door in the aft cabin bulkhead. The door lets in plenty of light and combines with two additional windows in the aft bulkhead to provide a clear line of sight from the helm to the cockpit.
The galley and helm are along the deckhouse`s port side, and a dinette - convertible to a berth - and mate`s seat are along the starboard side. The galley itself contains a propane range with oven, a deep stainless sink, a refrigerator and ample storage.
Forecastle access is down a couple of steps from the starboard side of the deckhouse just forward of the mate`s seat. Forward is a king-size bed, complete with twin reading lamps; aft is the head/shower combination. There is a reasonably sized hanging locker to starboard and a step up to the bed. Graf noted that since the bed is king size, a couple sharing it can sleep athwartship and not have to crawl over each other to get out of bed.
There is also a quarter berth, down a couple of steps from the aft port side of the deckhouse, just inside the door from the aft deck.
The interior utilizes light-colored wood, carpet and upholstery to create a bright and cheerful ambiance, which is accentuated by the large windshield and long deckhouse side windows. The use of some darker wood accents is a nice touch. And in a nod to creative design, there`s plenty of room to move around.
UNDER WAY
The real test of this design comes in running the boat on the water. Since there is only one finished C90, and it was inside at the Seattle show, our test boat in the water was an L90, whose hull was the plug for the mold out of which the C90 was taken. The L90 is, in effect, an open boat, complete with a port center console and plenty of perimeter seating. Its hull is identical to the hull of the new cruiser.
With Graf at the helm, we backed out of the slip at Elliott Bay Marina and, making use of the stern thruster, we swung into a fairway that must have been the length of a football field, between two rows of docked boats. Centering the vessel in the fairway, Graf took his hands off the wheel and the vessel tracked straight to the breakwater at the end of the fairway. If the hull design and construction had not been perfect, such a straight run would have been impossible. We made 4.3 mph down the fairway, with the engine ticking over at 800 rpm.
Once out into the open water, we started "playing around." At 2,200 rpm, we made 11 mph and threw no real wake. With the engine turning over at 2,500 rpm, we made 16.2 mph. At 3,000 rpm, we ran at 21.1 mph, and at 3,400 rpm we were doing 24 mph. The vessel tracked perfectly at all speeds and responded to the helm smartly. I moved from gunnel to gunnel (and at more than 200 pounds I`m on the husky side) and that movement had no effect on the vessel.
In addition to our run through the ferry wake highlighted previously, one final test involved bringing the vessel to a complete stop, putting the helm hard over and slowly increasing power to wide-open throttle. With the helm to port, the vessel leaned slightly to starboard and, as the engine speed increased, it leveled out and then leaned very slightly into the turn. A number of cats on the market lean opposite the turn and never recover through the entire power range.
The new Aspen is an ingenious vessel designed from the outset to be sea-kindly and economical. It cruises comfortably at speeds that similarly sized full-displacement vessels, both power and sail, can only dream about. The single small diesel engine keeps the initial cost down and reduces ongoing maintenance costs. The built-in solar charging system, when combined with the efficient lighting system and appliances, gives the vessel a "green tinge" demanded by many, and since the C90 can live comfortably on a trailer, boating costs can be further reduced.
Boaters who might hesitate to embrace a new type and style of boat should remember that the guy who designed and developed Aspen is the same one who designed and developed Glacier Bay. By the time he left Glacier, he had turned it into one of the world`s largest power cat manufacturers. Plus, you can have all of this technical knowhow and a fun boat for right around $180,000.
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This article first appeared in the April 2010 issue of Sea Magazine. All or parts of the information contained in this article might be outdated. |
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