Ericsson Submerged Screw Propeller
US 588Contra-Rotating Helical Spiral Blades, Hydrofoil Camber, and Submerged Shaft Thrust
How It Works: Step-by-Step Mechanical & Physical Breakdown
A steam engine drives an axial propeller shaft passing through a watertight stuffing box in the stern below the waterline. The shaft turns a hub fitted with curved helical blades shaped like sections of a giant screw thread. As the blades slice obliquely through the water, their cambered hydrofoil cross-section accelerates a cylindrical column of water backwards (). By Newton's third law, the water exerts an equal and opposite forward reaction force (thrust ) transmitted through a heavy thrust bearing into the vessel's hull, driving the ship forward with high hydrodynamic efficiency.
Interactive Real-Time Physical Simulation
Detailed Component Architecture
1Helical Screw Hydrofoil Blades
Blades designed with constant or progressive axial pitch (axial advance per revolution: ). The cross-sections act as submerged hydrofoils, generating dynamic lift perpendicular to the relative inflow velocity vector .
2Concentric Shaft Contra-Rotating Drive
To eliminate rotational swirl and torque steer in early short-diameter screws, Ericsson geared two counter-rotating wheels. The aft propeller recovered kinetic energy from the rotational wake of the forward propeller, ensuring zero net yaw moment on the rudder.
3Submerged Stern Tube & Thrust Bearing
The shaft passes through a lignum-vitae water-lubricated bearing and hemp packing gland in the sternpost. A multi-collar thrust bearing transmits forward axial thrust () directly to the keel structural stringers.
4Blade Camber, Skew, and Hub Boss Streamlining
The blade roots transition smoothly into a tapered ellipsoidal hub boss (), preventing flow separation at the inner radii. Backwards rake angles () increase clearance between the blade tips and the ship's stern frame, suppressing propeller-induced hull pressure pulses.
5Bevel Reversing Geartrain & Disengaging Clutch
A pair of heavy cast-iron bevel gears with crowned teeth links the primary engine crank to the outer sleeve shaft and inner core shaft. The gear assembly maintains precise counter-rotational synchronization while absorbing peak torque pulsations () from single-expansion steam cylinders.
Governing Equations & Colorized Principles
Screw Propeller Thrust & Axial Momentum Theory
Hydrodynamics & Contra-Rotating Screw PropulsionThe governing physical relationship for describes how and system equilibrium and energy transfer according to first principles.
Engine Shaft Speed
Adjusting Engine Shaft Speed modulates real-time physical telemetry states and governing forces in the simulated mechanism.
Concentric shafts drive two contra-rotating screw wheels enclosed in cylindrical shroud rings, canceling gyroscopic torque and rotational wake turbulence.
Interactive Schematic Sheet (Fig. 1)
Sectional drawing showing concentric propeller shafts, forward and aft helical blade hubs, and submerged rudder integration.
Select Any Numbered Pin
Click pins on the schematic or select from the list below to inspect historical specifications.
Why It Still Matters
Ericsson's submerged screw propeller replaced paddle wheels worldwide and made modern ocean shipping, container fleets, and armored naval warships possible. Ericsson later designed the USS Monitor (1862), whose submerged screw propeller and revolving armored turret revolutionized naval warfare forever.
Legal Claims Decoder (2 Numbered Claims)
The Historical Bottleneck
Why Prior Art Failed
- •Archimedean water screws were long, full-turn helical augers that choked with weeds and suffered massive skin-friction drag.
- •Francis Pettit Smith's 1836 British screw was an oversized two-turn wood spiral that broke in half during trials.
- •The British Admiralty rejected Ericsson's 1837 prototype (the Francis B. Ogden) on the false theoretical belief that steering from the stern would be impossible with a screw propeller!