Kitchen Rudder, invented 1914, installed 2003 to maneuver Gertrude- a boat powered by a vintage 3 HP two-cycle engine
Start here and play video - click white arrow - to pause video click double bars ll - best viewed full screen
Kitchen's 1914 British Patent #869,051 ( USA patent #1,186,210) described a clever mechanism consisting
of two clamshell like deflectors that encircled a boat's propeller. These can be opened or closed in unison.
When closed, all of the propeller stream is reversed and then acts in a forward direction causing the boat
to move backwards. The engine usually operates at one speed, always in forward rotation. Although this
reversing capability was the main objective of the invention, it is soon discovered that a boat fitted with a
Kitchen Rudder can be maneuvered at least equal to a vessel with twin screws. This unprecedented
maneuverability encouraged the British Admiralty to install Kitchen Rudders on open vessels used for rescue
missions where ability to maneuver was crucial.
Gertrude - owner built replica circa 1900 Power Dory powered by
a vintage single cylinder 3HP St Lawrence two-cycle marine
engine. As is typical, engine is directly connected to propeller.
When engine operates, propeller rotates, boat moves. In place of
transmission, owner designed/built Kitchen Rudder was installed.
This device provides unprecedented maneuverability including
neutral, reverse and stern thrust, much better than a
Two-cycle engines use few moving parts compared to many parts used for construction of four-cycle engines where sequence is
controlled by valves opening and closing by the action of a rotating cam shaft. The simple two-cycle construction is one reason for
their popularity early 1900. Two-cycle engines are dependable and easy to repair. From about 1900 to 1920, many organizations
manufactured two cycle marine engines. By 1950 most small marine engines were outboard style. Now because of environmental
concern, almost all small marine engines use the four stroke cycle. St Lawrence Engine Company manufactured two-cycle marine
engines from 1905 to about 1949 at a facility located in Canada at Brockville, Ontario. Only minor improvements occurred during the
period, notably changing to aluminium pistons about 1935.
Typical two cylinder St
marine engine Circa
1935 Bore 3 1/4",
Stroke 3/1/2' x 2
Flywheel is 14"
diameter 6 HP @ 850
Typical single cylinder
St Lawrence two-cycle
marine engine Circa
1949 Bore 3 1/4",
Stroke 3 1/2'" Flywheel
is 12" diameter 3 HP @
The advancement of gas engine use occurred as a result of understanding the advantage of compression prior to ignition. This
occurred in 1876 in Germany by Nikolaus Otto. Otto's engine used a four-stroke cycle where combustion occurred once during two
engine revolutions. Even now the four-stroke cycle is referred to as the Otto cycle.
During 1890 a Scottish engineer, Sir Dugald Clerk, introduced an engine where combustion occurred each engine revolution. This is
referred to as the two-stroke cycle. Clerk's engine used a separate chamber for taking in the combustible charge and transferring it to
the power cylinder. In 1892, Frederic Caswell Cock, an Englishman, patented the two-cycle method where combustible charge entered
the crankcase before transfer to the combustion chamber via an integral transfer port.
The content in this site is for information purposes only. The author assumes no liability for inaccurate or
incomplete information in this site or contained in any links that are provided solely as a convenience.