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Cobalt Yachts 46

Star of the show. From model to supermodel.

December 12, 2007
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Besides designing a boat to go a certain speed, sleep a set number of guests, and displace a specific amount of water, most manufacturers want a hull that pops from a single mold. Vertical transoms and straight or slightly flared topsides fulfill this parameter nicely. That’s why so many cruisers look alike. Yes, these simple shapes have real benefits, but they owe their existence as much to bean counting as to seaworthiness.

Now look at the Cobalt Yachts 46. The fluted aft topsides are as eye-pleasing as the turn of a cover girl’s waist. The tumblehome is delightful. Note the sloping transom and the way in which it integrates the slickest hydraulic lift platform you’re likely to see. It takes split molds, three in all, to shape such a curvaceous boat. Design is not subordinate to cost aboard the 46.

The 46’s function, elegance, and top engineering-a Cummins MerCruiser’s Zeus propulsion system, for instance-are linked. Each element isn’t just the result of the others but, in fact, allows the others to flourish. There may be reasons to pass on this boat, money being a main culprit, but few cruisers will make you as hungry to take a test ride as the 46.

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Low Rider

****The quest for maximum headroom also makes many cruisers look like kissing cousins. A hull needs stringers for support, and for a boat to be strong, they need to run all the way to the bow. This imposes the minimum height of the cabin sole. A quick route to avoiding “stooping headroom” is to balloon the foredeck, but that makes for a too-tall cabin trunk and a perilous slope for walking forward to handle lines. Ballooned cabin trunks rarely look good, and they provoke derisive comments. Legendary designer N.G. Herreshoff once said: “If I want more headroom, I’ll go on deck.” To avoid a boat that looks like a bleach bottle, some builders taper down the forward stringers to nothing, but that seriously compromises the boat’s structural integrity.

Wanting a boat that looks sleek but uses full height, full-length stringers, Cobalt loosened the purse strings and engineered a new stringer system. By spreading the stringers outboard and running them under furniture, they could remain full height. The hull, therefore, is still robustly supported and the resulting headroom is 7′. Except for some attractive, functional camber, the foredeck is flat, too. It works. This is one handsome boat.

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Question: How many caulk lines are acceptable aboard a luxury cruiser? These goopy furrows, necessary to hide the gap between two mating but separate parts, look okay when brand new. But once the boat is in service, they turn tea-stained, highlighting rather than hiding the gaps they were intended to conceal. Hardtops and arches are glaring examples. But look at the 46’s hardtop and you won’t see a single seam. Cobalt again used a split mold, this one six parts, to make a seamless, one-part structure.

Of all structural points, the hull-to-deck joint takes the most abuse as hull and deck constantly alternate between tension and compression. It’s a common source of leaks. Cobalt’s solution uses a flush-fit joint in which the deck flange mates into a rabbet-a perfect-fit recess-on the hull flange. This rabbeted joint is self-supporting and water resistant, better than the typical shoebox fit. Plus, the joint is glued, bolted, and fiberglassed. Few boats possess as robust a hull-to-deck joint.

Run, Boy

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****Fitted with twin 473-bhp Cummins MerCruiser QSB diesels and joystick-controlled Zeus drives, the 46 has the speed and efficiency to go with its looks. In joystick mode, the Zeus drives rotate in independent directions, while the onboard computer independently shifts each between forward and reverse and applies higher or lower rpm, also independently, to make the boat follow the simple movement of your hand on the joystick. Need to slide diagonally backward while countering a headwind to slip the boat in a cross current? Move the stick. The boat mimics the movement.

Zeus drives are more efficient than traditional inboards. Their aft-facing propellers are mounted in shallow tunnels. At 30 mph, my tester delivered nearly 1 mpg. Zeus drives also provide agile handling. It’s worth a test ride to experience the sensation of zipping around in a boat this big. Part-time underwater exhaust (through-hull at lower speeds) and less vibration make Zeus-powered boats quieter than inboards, too. I recorded a hushed 82 decibels at 30 mph. Top speed is 37 mph.

This demonstrates excellent performance compared to straight shafts. But how does it compare to boats powered by Volvo Penta’s IPS? IPS drives mount on the deadrise, the props face forward, and exhaust is underwater at all rpm. Formula’s 45 Yacht ($931,200 with twin 435-hp IPS 600s) tops out at 37.3 mph, burning 31 gph at 30 mph while emitting 78 dB-A. Tiara’s 4300 Sovran ($640,600 also with twin 435-bhp IPS 600s) hits 37.8 mph and burns 30 gph at 30 mph, emitting 82 dB-A. The Formula weighs 2,000 pounds less than the 46, the Tiara 3,000 pounds less. Both achieved marginally higher top speeds using less horsepower and burning less fuel at both full throttle and the 30-mph cruise benchmark. However, the differences in weight, as well as the boats’ hard-sided coupe helm enclosures, are likely just as responsible for their better efficiency.

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Picking a boat such as this is about amenities as much as performance. So head belowdecks on the 46. Hit a switch. The microwave rises out of the galley counter. Run your hands across the real leather, real granite, and real glass tile. The sensation is superior to materials preceded by the word “faux.” At the fuel dock, enjoy the convenience of port and starboard tank fills. Fold out the solid teak cockpit table, cleverly hinged and hidden within the aft lounge backrest. In short, the more you explore this boat, the more it pleases. That, if anything, truly sets it apart.

EXTRA POINT: Spreading the stringers in the bow increases headroom. The sole is bonded to the stringers and athwartship frames are added, so hull stiffness isn’t sacrificed.

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