Dave Gerr - Boat Mechanical Systems Handbook-How to Design, Install, and Recognize Proper Systems in Boats

and Canadian navies before World War II, and

it won raves from those who used it. Sales and

marketing here in the U.S.—under 1916 U.S.

Patent No. 1,186,210—was spotty, though.

The McNab Company—first of Bridgeport,

Connecticut, and later of Yonkers, New

York—had the American license. Though they

made successful installations on everything

from outboards (yes, outboard motors with

Kitchen rudders) to large ships, all traces of

it seem to have vanished.

KITCHENSTEERINGMECHANISM One possi-

ble difficulty is the steering mechanism. The

two halves of the rudder are steered in

unison with a more-or-less conventional

tiller, but that tiller is itself a worm-screw

that controls the closing and opening of the

two conical half-circles. This is reliable and

apparently free from failures, but back in

1916 it required complex mechanical link-

ages to run controls to a remote helm station.

Today, however, with modern hydraulics,

such controls would be inexpensive and reli-

able to install. You would need only one stan-

dard hydraulic steering cylinder and one sec-

ond half-circle closing (reversing) hydraulic

cylinder—not a very powerful one at that. If

you installed a Kitchen rudder, you would

have to add the cost of fabricating the rudder

and the second hydraulic cylinder. (You

could subtract the cost and, not at all inci-

dental, the weight of the reverse gear, if you

could get a reduction gear only.) You would

also have effectively added—at no extra cost

or weight—a complete stern thruster for

incredible maneuverability in harbor. For

years I’ve been promising myself that the

next motor cruiser I design will have a

Kitchen rudder. Maybe one day it will.

The Kitchen rudder wouldn’t be suitable

for planing hulls or for most boats cruising

at speed-length ratios over 1.5 or so, as the

extra drag from the Kitchen rudder would be

too great a drawback.

Harrison’s Patent Rudder

Interestingly, another rudder shares a vague

similarity with the Kitchen rudder. This is the

Harrison patent rudder. Figure 13-3 shows a

rudder that is a half-circle surrounding the top

portion of the propeller. Mounted on a single

rudder stock, these rudders were fitted to fast

steam launches many, many years ago. The

Harrison rudder worked well and gave

slightly better water flow to and from the

prop. Twin-screw vessels sometimes had two

quarter-circle Harrison-type rudders installed,

one on the outboard side of each rudder. This,

too, worked well. Though effective and worth

noting, the Harrison patent rudder didn’t

generate the broad array of advantages that

the Kitchen rudder did and still does.

A very similar rudder is used on some

surface-drive propeller installations with ex-

cellent results.

Steerable Kort Nozzles

A vaguely related ring-form rudder is the

steerable Kort nozzle (Figure 13-4). This is the

standard Kort nozzle most commonly used on

tugs and trawlers to increase low-speed

thrust. The common installation is to have the

PART FOUR:RUDDERS AND STEERING SYSTEMS

Figure 13-3. Harrison patent rudder