Flats Cat Boats 21 Foot Review, the Texas Cat That Runs in Inches

What Flats Cat boats are, and where the 21 fits

Flats Cat boats are small fiberglass catamarans built in Rosenberg, Texas, for anglers who fish the skinniest water on the Gulf Coast: back lakes, marshes and the shallow flats of Texas bays. The company builds three models today, a 17, a 19 and the 21, and the 21 is both the largest and the original. Flats Cat says its first boat was the 21 in 1991, followed by an 18.6 in 1995, the 17 in 2001 and the 19 a year later.

The builder's pitch is three words, smoothest, driest, shallowest, and the 21 is pitched as the boat for anglers who need more space, power and storage than the smaller cats. It keeps their shallow-water ability, with the same 4-inch draft at rest and 3.5-inch minimum running depth, but adds a much larger front casting platform and a smoother ride in choppy bays.

Bill Allison's patented hull

Flats Cat exists because of a bad back. Founder Bill Allison, a college football player, was injured and found traditional boats too hard on his spine, so he spent years drawing and researching a catamaran that would run smooth, dry and shallow. He filed for a patent in May 1988, and US Patent 4,870,919 for a catamaran type boat was granted on October 3, 1989.

The patent explains the thinking. It notes that catamaran pontoons with upswept forward bottoms generate lift and reduce pitching because the two hulls rarely hit a wave at the same instant, and it sets out the goal of a fishing boat fast enough to reach the grounds quickly yet able to cross water as shallow as three or four inches. The first boats were aluminum pontoons joined by welded beams. Allison later concluded that aluminum was too noisy and spooked fish, and moved production to fiberglass. Flats Cat also credits research help from Texas A&M.

The numbers behind the 21

Flats Cat publishes an unusually shallow-water-focused spec sheet. The 21 has a 7-foot 6-inch beam and a 7-foot bottom, weighs 1,650 pounds, and has a 27-inch transom. Take-off depth is 6 inches, minimum running depth 3.5 inches, draft at rest 4 inches, and the builder says it planes in 10 feet. Recommended power is a 150 hp outboard, mounted on a 6-inch Bob's Action Jack plate, and fuel capacity is 40 gallons.

Those figures compare with 1,400 pounds and 115 hp for the 19 on the same beam. The 21 is the one to choose if you regularly carry three anglers, fish open bay water as well as back lakes, or want more deck to cast from.

• Beam 7 ft 6 in, bottom 7 ft, weight 1,650 lb
• Draft at rest 4 in, minimum running depth 3.5 in, take-off depth 6 in
• Planing distance 10 ft
• Recommended power 150 hp, fuel 40 gal
• Transom height 27 in with a 6-inch jack plate

Deck layout and standard equipment

The deck is simple and built around poling, wading and casting. A large front casting platform has three hatches with Trim-Lok seals, and dual rear platforms carry more hatches. The console is fiberglassed to the deck, with an aluminum welded console rail, a tinted windscreen, a non-skid top and a six-switch panel. A custom leaning post with a backrest and storage, an insulated livewell with fill, recirculation and aeration, one-way scuppers that keep the boat self-bailing, pop-up cleats and hydraulic steering are standard.

The hull is foam filled and Flats Cat calls the design unsinkable. Wiring runs through a conduit from the console to the bow for the trolling motor. The listed accessories include an 8-foot Raptor shallow-water anchor, a Minn Kota iPilot package, a Wet Sounds sound bar, trim tabs, a light bar, bucket seats on Shockwave mounts, an elevated ice chest, a removable sport top and a wade ladder with a handrail. A single-axle trailer is standard, with a tandem option.

The company after Bill Allison

Bill Allison died in 2014. Gina ran the company afterward, and Chris Mapp took over in 2020. Every boat is still built start to finish in Rosenberg, from hull lamination and gelcoat to wiring and rigging. Under the new ownership, the 2024 boats moved to all-composite construction, and the company signed Sonny Cook Marine in Port O'Connor as a dealer. A 2023 walkthrough by the Texas Fishing Force channel toured the plant and introduced the 2024 model.

Flats Cat boats have also proved useful far from the fishing grounds. The company says its boats were used as rescue craft in flooded neighborhoods during Hurricane Harvey, where few other boats could maneuver in such shallow water.

Who the 21 suits, and who it does not

The 21 is a specialist. It suits Texas and Louisiana anglers who sight-cast for redfish and trout in inches of water, wade fishermen who want a stable platform to step off, and duck hunters who need to cross mud flats. The catamaran hull trades some of the predictable feel of a monohull bay boat for its shallow running and smooth ride in a short chop.

It is not an offshore boat, and it is not a family runabout. With 40 gallons of fuel and a small console, it is designed for bays and marshes. Ownership costs are low, roughly $3,000 to $7,500 a year for insurance, outboard service, trailer upkeep and fuel, which is a large part of its appeal.

Buying a used Flats Cat 21

Used Flats Cats turn up mostly on the Texas coast, often privately. Because the 21 has been built since 1991, you will see aluminum boats, early fiberglass boats and the newer composite boats under the same name. Check the hull material and year carefully, and expect the newest boats to cost several times more than the oldest.

Shallow-water boats live hard lives. Inspect the bottoms of both hulls for gouges and repairs from oyster shell and running aground, check the transom and jack plate mounting for cracks, and look for soft spots in the casting platform. Older outboards are the most common big expense, so price a repower into any boat with an old two-stroke.