Gulf Coast Outdoors - By Larry Hyland
While many inventions and innovations are the result of blind luck or a fortuitous accident, most are the product of a person trying to solve a problem. Bill Allison of Rosenberg, Texas was presented with just such a problem in the mid 1980s when he determined the pounding he was taking from his monohull boat was just too much for his back and knees.
A college-educated biologist and self-taught nautical engineer, Bill set about designing a boat that would dampen the pounding and allow him to spend less stressful days fishing the shallow bays of South Texas. His initial efforts resulted in a 14-foot hydrofoil that would hoist two large men out of the water with a 20HP engine. The boat definitely ran smoothly with its hull above the water, but, as Allison explained, “it was the wettest boat I ever rode in!” Abandoning the hydrofoil concept, Allison began working on a design that would eventually wear the Flats Cat logo.
This next step in development had its own set of lessons that should be passed along to budding boat designers. Purchasing a saw, some marine plywood and all manner of woodworking tools, Allison built his first boat in his shop on the main drag of Rosenberg.
While the resultant boat performed well, a painful accident with a saw convinced him that, while he was on the right track, plywood was not the way to go. Mentally divorcing himself from Flats Cat hull 001, he rolled the boat in front of his shop, put a sign on it and sold it two hours later. With the saw safely out of the way, Allison next purchased a welder, a supply of flat stock and set about teaching himself how to weld.
Flats Cat 002 was an equally impressive performer, but would have been prohibitively expensive to mass -produce. His choices bounded by pain at one end and the laws of economics at the other, hull 003 and the subsequent 350-plus Flats Cats boats launched since 1985 run on fiberglass hulls.
After spending an afternoon in Allison’s 20,000-square-foot production facility on the outskirts of Rosenberg, I gained a better appreciation of the boats’ rugged construction. Preferring proven materials to synthetics, Allison puts a lot of wood in his boats and makes no apologies.
The transoms are a 1 1/2 sandwich of resin-impregnated marine ply from Greenwood Forest Products with ¾-inch planking in the decks. The sponsons (hulls) are stiffened with resin-impregnated, end-cut balsa in the sides and along the planing surfaces with a 6-inch-tall stringer running down the centerline. The hulls are further stiffened by lateral bulkheads and the voids in the hulls are filled with solid foam blocks before the deck is mated to the hull.
The foam blocks are trimmed to size with a “hot wire” cutter which seals the end cells of the material and makes them impervious to water intrusion. A series of sea trials the next day confirmed the impressions I formed in the shop — the Flats Cat is a stiff package and will take whatever its owner can dish out.
I have examined a lot of multihull boats in the last few years and I can honestly say I’ve never seen anything like the Flats Cat. The lack of copycat designs stems from the fact Allison secured a patent for his boat and will sue your brains out if you try to “splash” one of his hulls.
The outboard hull sides are effectively vertical and run parallel to the caprail from stem to stern. The sponsons pick up at the bow and rapidly flow inboard to a point about one-third the hull length, then run straight back to the transom. The patented aspect of the hull is the magic going on between the sponsons. The distance between the bottom of the hulls is less than the distance at the top.
Those familiar with geometry will recognize this as a trapezoid with its top wider than the base. In theory and in practice, the unique sponson configuration creates a column of water which courses between the hulls to the prop. Believe it or not, this allows the prop to grab water and push the boat, even when the engine is jacked up to the point where the prop is above the planing surface of the hulls. The hull is equally unbelievable when viewed from the side. Even though the twin hulls are devoid of protrusions or strakes, it would be incorrect to label the Flats Cat a “flatbottomed” boat. The hulls are gently curved from bow to transom, a nautical interpretation of the runner on a rocking chair.
Departing Rosenberg in the wee hours of a Saturday morning, we traveled 2 1/2 hours south to Rockport to run 21- and 17-footers. The 21-foot model has been the mainstay of the fleet and the 17-footer is new for 2001. With licensed fishing guide Tom Kruft at the helm of his fully rigged, 21-foot Flats Cat, we motored from the launch ramp toward the shallows of North Bay at Aransas Pass.
Low speed handling was acceptable but sluggish, understandable given the keel-less hulls. Backing was equally tricky for the same reason. Throttling up the big 125HP Mercury, the boat quickly came to plane with minimal bow-rise. Up and running, the engine gave a throaty roar, suggesting cavitation and overreving, but the tachometer indicated normal operations.
Tom pointed out this was typical since the engine’s through-hub exhaust is actually above the waterline at cruise. Cruising in the high 30s, we transited the flats running high and wide in around six inches of water. Dropping off plane the boat settled calmly, drawing around three inches. After poling around for a few minutes to sample the boat’s fishability,” Tom advanced the throttle to max and the boat was once again on plane.
Coming to plane in shallow water is not as simple as it sounds and, for a few brief seconds, the engine had to double as a seaweed and mud pump to get things moving. This necessitates outfitting the Flats Cat powerplant with a four-bladed stainless steel prop.Bill motored over and I mounted the 17-foot to put it through its paces. Performance characteristics coming out of the hole were nearly identical with the 21-footer, and the 90HP Yamaha cruised the 17 in the mid-30s and would sprint into the mid-40s at full bore.
The 17 is a nimble little package and elicited a stable ride in 1- to 2-footers. Up and running, there is practically nothing below the surface of the water, so sharp turns are to be avoided. With that minor caveat noted, the rest of the ride was enjoyable. Returning to the ramp, Bill brought the 17 alongside and I could see the column of water flowing between the hulls. I also noted Bill was running in water that honestly was knee-deep to the seagulls that scrambled out of his way as he roared down the beach.
It’s nice to find a product that lives up to the hype and the Flats Cat will definitely do what its designer says it can do. Well built and rugged, it can take a pounding, run on a wet lawn, and provide a stable fishing platform. A boat guaranteed to draw a crowd at the launch ramp, the Flats Cat is priced right for a “custom” boat.
Gulf Coast Boating - By Al Rogers
"The catamaran hull was designed and is built for a smooth ride in rough seas and glide across water less than an inch deep."
"In rough water, I could put a soft drink in the tower, and it wouldn't spill."
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