Sea trials on this stylish vessel exceeded all our performance expectations and validated our tunnel slot concept. Originally a custom design, plans are now available at a fraction of the original design fee. And while the first was custom built, this is not a project beyond the abilities of a qualified do-it-yourselfer.
Construction uses the latest in modern composite technology - vinylester resins, non-woven unidirectional reinforcements, vacuum bagged PVC or balsa coring, and carbon fiber reinforcements at critical areas. Layup is done over a simple male mold resulting in a structure that is amazingly strong and lightweight. There is absolutely no wood or plywood used in the boat; even non-structural interior members are foam cored. Yet our methods are surprisingly simple and low cost (see recommended texts which give the details).
Power is by twin stern-mounted motors using either surface-piercing drives or I/O units. Horsepower in the range of 900-1100 gives speeds in the 50-60 MPH range depending on load, and with a generous fuel capacity. Yet this is a practical boat too. Accommodations are spacious. A huge cockpit with convenient swim step makes carrying and launching a large inflatable dinghy easy. The cabin includes a queen-sized bed and huge dinette that seats six, plus complete galley and enclosed head with shower, all with full headroom.
NOTE: COMPLETE PLANS include hull lines, offsets (corrected so you can lay out members directly without complete lofting), laminate schedule, all working drawings and required details. Full-size patterns are NOT available. REVIEW PLANS are also available; these include all the above except for hull lines, offsets, and laminate schedule. The price of REVIEW PLANS can later be applied to the purchase of COMPLETE PLANS (required to build the boat) if you decide to build. Our typical STUDY PLAN PAK is NOT available otherwise.
"SLOT MACHINE" was reviewed and tested by Steve Temple, editor of The WESTERN BOATMAN magazine in July/August 1990 - partial text as follows:
Monohulls and catamarans both have advantages. Those in favor of the deep-vee hulls point to their rough-water capabilities; advocates of twin-hull powerboats boast of higher speeds. Where one hull type excels, though, the other is usually second-best. Imagine the excitement that would be caused if a designer could somehow produce a hull that bridged the gap betwen the two - a best-of-both-worlds boat with an easily driven hull that could handle heavy or following seas.
Such a design is not just a dream. The Slot Machine 46 is a one-off express cruiser that combines the advantages of monohulls and catamarans. By using a proven racing design - the tunnel hull - and by adding a new wrinkle, this boat's tunnel which is actually a "tunnel slot", as described by designer Ken Hankinson because it is proportionately narrower (in comparison to the beam) than those employed on its competition-bred cousins. The underbody is essentially a vee-hull with 18 degrees of deadrise and a 30-inch groove cut down the middle. By contrast, a true catamaran is two separate hulls held together by a deck.
The difference between these design concepts becomes evident when handling Slot Machine. A conventional catamaran usually turns flat, or even leans outboard, sometimes to the point of tripping over its outer chine (hence the common use of a beveled or "anti-trip" chine). A deep-vee hull, on the other hand, leans steeply inboard, and tends to fall off plane on particularly sharp maneuvers.
The Slot Machine does neither. When steering hard-over at full speed, the boat banks gently inward at a reassuring angle. With the hull slightly heeled in a turn, the tunnel edge provides lateral plane - in effect, a small keel - that grabs the water and keeps the hull from skidding outboard. As a result, the turning radius is unusually short and the helm quite responsove. (Moreover, low-speed wandering is elimiated.) The hull will eventually stall if you keep the wheel all the way over, but a minor steering correction maintains planing speeds.
Another performance advantage of the tunnel-slot is reduction in the amount of wetted surface that causes drag and robs power and speed. On the other hand, the tunnel-slot reduces reserve buoyancy somewhat, so the boat doesn't hop on plane; it climbs steadily out of the hole.
Despite the Slot Machine's difference from true catamarans, its tunnel-slot is nevertheless big enough to have aerodynamic benefits. Like a catamaran, compressed air flow passing underneath provides both lift for higher speed and a cushion for re-entry. We can vouch for the latter characteristic after making a full-throttle run at a ferry wake. The hull lifted off as smoothly as an elevator and then landed just as softly - no slamming, wobbling, or stuffing of the bow. The attitude of the bow was remarkably flat in all sea conditions, with or without the application of the Kiefhaefer K-planes. The tabs are not needed for getting on plane, but are particularly effective for transverse trimming, in a crosswind or beam sea.
The tunnel-slot is not so big that it induces kiting (or chine walking) because of its excessive lift. However, Hankinson says he intended the boat for speeds in the low 50-knot range (60 mph). Even though its construction certainly appears to be tough enough, this craft has not been tested with larger engines and at higher speeds. No doubt faster performance is possible, but anything about 60 mph puts the boat in the competition category.
Slot Machine's owner originally requested a boat for weekend cruising among the Channel Islands off Southern California. Explains Hankinson, "The philosophy behind the tunnel-slot hull was not to design the ultimate high-speed raceboat. Instead, the owner wanted a boat that would run at 40 to 45 knots in a wide variety of sea conditions, one that would allow him to get from point to point quickly, but in some degree of comfort."
In keeping with the owner's intended use, the boat's accommodations are far more spacious and comfortable than typically seen on sportboats, monohulls or otherwise. A queen-size berth athwartships is partially surrounded by a shelf with storage bins underneath. The semi-circular dinette to starboard can seat six adults, and can make up into a huge double berth. To port is a complete galley with CNG range, microwave over and refrigerator/freezer. Aft to starboard is an enclosed head with shower. The tunnel-slot and transverse ring-frame encroach somewhat on the interior layout, requiring an occasional "step-over" but they are minor inconveniences. (end of article excerpt)
Specifications and Photos