Jim Krogen's rugged displacement yachts are
born from workaday hulls.

    Today most people want to go fast; a boat that can’t cover 50 miles in two hours in almost any sea condition is soon traded for one that can, regardless of concomitant double-digit hourly fuel consumption and esoteric, tweaked-to-the-max powerplants. For a small but growing minority of boatmen, though, speed is unimportant; they prefer seaworthy, economical vessels driven by a single diesel (usually of the naturally aspirated persuasion) that can chug along at displacement speeds for up to a thousand miles on a tankful of fuel.
    Such yachts are known in the vernacular as “trawlers,” even though that term is more correctly used to describe a fishing boat dragging a net.
Few trawler-type yachts bear any resemblance whatsoever to true trawlers, other than the fact that both float are powered by internal combustion engines. A fishing trawler’s hull is full-bodied – some might even say “fat” – and designed to run heavily laden with fuel, ice,


and fish, while trawler yachts are more svelte, with a harder turn to the bilge and a less burdensome hull; many have chines and can run at semi-displacement speeds.

Body By Krogen
    One designer who sticks closely to traditional displacement hulls is Jim Krogen of Miami; Jim’s different from most yacht designers in that, armed with a degree in naval architecture (as in “big ships”) from the University of Michigan, he started out drawing commercial boats. “I don’t really know how I got started [designing yachts],” he says. “Although I’ve always been interested in yachts, most of my original work was commercial, and we still do a lot of commercial design – tugs, small tankers, cargo ships, landing craft for the Bahamas and Caribbean [cargo, not troops], and so forth.”
Commercial boats are primarily displacement hulls, and Jim figures this aspect of this work has influenced his yachts. While he based a fewsemi-displacement yachts on New England lobsterboat designs – they were soft-chined and “not real


fast” – he became better known for true trawler-types of strip-planked mahogany or plywood covered with fiberglass. In 1978, he teamed up with Art Kadey to design to design and market a stock 42-footer reflecting his earlier custom work; the resulting Krogen 42 is still sold today, 150 boats later. And the Kadey-Krogen line has expanded to include a 38’ shoal-draft sailboat, a recently introduced 54’ trawler yacht, and the unorthodox but charming Manatee.
    A lot of people don’t realize that you can’t build both a displacement and planing hull at the same time, says Jim, although a planing hull can be operated in the displacement mode. The hull that’s designed to go fast isn’t as efficient throttled back as a hull intended from the outset for slow going – “you can’t have both worlds.” But there are a lot more advantages to designing for displacement speeds than just fuel efficiency, and most of them center about the engines.


Jim Krogen's experience at sea is reflected in his able, functional yachts.

  The Krogen 42 is perfect for an overnight jaunt to the other side of the bay, or a six-month voyage to the other side of the Equator; her rugged, full-displacement hull is designed for passagemaking.

    If a boat can’t plane, she doesn’t need very big engines; it doesn’t take much relative horsepower to push a boat to a speed/length ratio of 1.34 or so, which represents roughly the optimum displacement speed of a particular hull. (The speed/length ratio is the speed of the boat in knots divided by the square root of the waterline length.) At higher ratios than this, the hull is trying to get “over the hump” into a semi-planing mode by climbing her own bow wave; this is like driving your car up a hill – only the thing is, the farther up you go, the steeper the hill gets.
    Boosting the speed/length ratio from 1.34 to 2.0 (into the semi-planing mode – true planning starts at a ratio of about 4.0) takes a tremendous increase in horsepower. More horsepower means bigger, heavier engines, or more of them, or both – this in spite of the sensitivity to weight and trim of the planning hull. Add bigger fuel tanks to handle the exponentially increased consumption, a generally elevated level of complexity, and astronomically higher initial and operating costs, and you see that there’s more to going fast than just advancing the throttles. Since there’s also less room available for stowage and living space, more dollars are buying you less boat – except when she’s planning, of course. 

Some people don’t care about planing, though; they’re more interested in cruising hither and yon, nosing into out-of-the-way harbors and creeks, and generally enjoying themselves while aboard; when it’s time to go south for the winter, they can run all the way to Florida without stopping for fuel. These are the folks who buy Jim Krogen’s boats. “In general, people who buy trawler yachts – Kadey-Krogens, at least – are very experienced boatmen,” says Jim. “Most have come from sailboats, and are happy and comfortable with single-screw. They know what to expect as far as handling goes, they know how to use spring lines, and so forth. We offer the 42 with twin screw, but so far only a few have been sold that way.” Contrary to what most twin-screw powerboatmen think, handling a single-engined boat around the marina isn’t very hard – it just takes practice – and there are some distinct advantages to having only one engine.

    Adding a second engine doesn’t do much for the speed of a displacement hull, assuming she was properly powered to begin with; once the s/1 ratio hits the magic 1.34 value, doubling the horsepower won’t push it very much farther up the resistance curve. In a displacement boat, twin screws offer improved close-quarters maneuverability and the extra reliability of a “spare” engine; how important either of these are, especially considering the dependability of the modern diesel, is a matter of opinion.
There are trade-offs. A single prop shaft lives along the centerline where it, along with its rudder and propeller, can be protected by a skeg molded or otherwise built into the hull. Twin screws don’t have this security – they hang out to port and starboard in the path of whatever debris happens to pass under the hull. Touch the bottom, and you may very well wrap up a prop and/or rudder.
   Cruising boatmen like to “gunkhole” where the water is thin, and don’t like shelling out long green to boatyards whenever they miscalculate water depth – the “advantages” of twin screws aren’t all that apparent to boatmen like these.
    Sailors, of course, go a ground all the time, their underwater gear “insured” by


several feet of keel. Old habits die hard, so when they see the light and switch to power, ragboatmen want a hull with good anti-grounding protection – which means a single screw.

Rolling Stock?
Many boatmen think that displacement hulls, without the damping effect of “hard” chines, roll more than their angular-bottomed sisters. (Anyone who’s spent the afternoon lying in the trough aboard a deep-V fishboat knows the fallacy of this reasoning.) Jim disagrees, saying, “If the underwater shape has a good deadrise, and the turn of the bilge is kept reasonably high, the boat won’t roll so much.” The problem, he continues, stems from designers drawing hulls with semi-circular sectional shapes.
    When an errant wake passes through the marina, Jim says, a Krogen 42 will roll 3 or 4 times before her motion dampens – other boats of her type seem to roll more under similar circumstances. “A light, planning, chine boat will probably dampen quicker, but if she’s heavy she’s going to roll as much as anything else.”
    At sea, a slight course change can often solve an uncomfortable rolling problem, and a steadying sail, if the boat is so rigged, can be effective with the relative wind anywhere from 45 degrees to 135 degrees off the bow. The ultimate solution is a set of stabilizers, which Kadey-Krogen does offer on the 42. “We recommend people use their boat before installing the stabilizers, though,” says Jim. “They can always be retrofit, but only five or six owners have asked us to do it.” 

The Marvelous Manatee
While the Krogen 42 was designed with passagemaking in mind – several have voyaged from Florida to Central America, California, Alaska, and beyond – the Jim Krogen creation that’s come to epitomize the cruising boat was never intended to leave Biscayne Bay. Based on the lines of a Florida lobsterboat, the 36-foot Manatee was designed for coastal cruising and living aboard, but not expected to join the Kadey-Krogen fleet.

    Jim was living aboard his sailboat when the Manatee was created. “I had a lot of female friends – not girlfriends, but acquaintances – who were envious of living aboard. They didn’t want sailboats, so I conceived of a simple, easily handled, houseboat-type vessel that would be suitable for a single man or woman, maybe with a child, to live aboard and use primarily on Biscayne Bay.”
Originally he was going to take the hull lines of a local 26-foot-squared ended lobsterboat and add a cabin, but interest in the Manatee was so great that Jim decided to lengthen her ten feet while keeping the lobsterboat underbody, round off her bow and stern, and market her has a Kadey-Krogen. The result it a boxy, almost Dutch-looking craft that’s rather homely until you step aboard-then, as long as you accept function as an aspect of beauty, she metamorphoses into something wondrous.
The after cockpit, shaded by the


upper-deck overhang, leads    into a huge saloon the equal of many shoreside living rooms. Like all Kadey-Krogens, the Manatee is built in Taiwan, so there’s plenty of rich teak, but the overheads are kept white, with molded-in “carlines,” each capped with varnished teak, that recall cabins of a more genteel era.
    Handholds run fore and aft along the overhead to provide security for moving about the saloon while underway. (This aboard a boat that Jim never expected to go to sea – wonder what nifty touches he adds to his “passagemakers”?)
    Farther forward to port is a fully equipped, kitchen-sized galley, with all kinds of lockers and drawers for cooking stuff.  The stove/oven is propane-fired, with is the only way to go if you really want to cruise; who wants to lie in a secluded anchorage and listen to a generator rattle away during cocktail hour? (Her twin 140-amp-hr. batteries will keep the 12v lights burning strongly long after the brandy and cigars are stowed.)
    The head lies to starboard, and forward is a big master stateroom with a queen sized centerline berth. There’s an L-shaped hanging locker and lots more drawers just waiting for you to move your things aboard.
    Piloting is done from the enclosed flying bridge; sunning is done on the spacious upper deck, unless you want to carry your dinghy there. The whole works is cruised along at a maximum of eight knots or by a 100-hp Volvo Penta TMD 31A diesel. Because she’s a displacement hull, the Manatee can run efficiently at any speed, so should you need extreme cruising range, just slow her down a bit – according to Jim’s calculations, at seven knots you’re looking at close to 1,000 nautical miles o 280 gallons of fuel, with a little left for emergencies.
    “Lots of people laughed at the Manatee when she first came out,” says Jim, “but we’ve sold 90-some boats now [since 1982]. We realize she’s not what you’d call ‘super-attractive,’ and doesn’t have graceful lines, but she’s turned out to be extremely functional and a great boat to cruise on – she’s very, very comfortable. Visibility form the helm station is great, performance is good, and, while not designed to go to sea, the Manatee is a better sea boat than I originally anticipated. All in all, we feel pretty good about her.”

    There’s a lot of cruising enjoyment out there for the boatman who doesn’t have to go fast; maybe you owe it to yourself to drop off plane for a while and try it out. If nothing else, you’ll meet great people like Jim Krogen – and that, if you ask me, is worth any number of 30-knot passages.

Reprinted with permission from Power and Motoryacht magazine.