A radial paddle wheel carries rigid floats on arms around a horizontal shaft. Explore the rotating wheel and calculate its radius, circumference, bottom-tip immersion and angular float spacing. These dimensions alone do not determine propulsion performance.
Declared Radial-Wheel Geometry
Enter a declared wheel diameter, bottom-tip immersion as a percentage of diameter and equally spaced float count. The worksheet reports exact geometry only, independent of hydrodynamic performance.
Equation Used
- The wheel is a perfect circle with a horizontal shaft and equally spaced radial floats.
- The waterline is horizontal and bottom-tip immersion is a declared fraction of wheel diameter.
- Float count is a whole number and affects angular spacing only.
- Float width, blade shape, hull interaction, waves, trim, slip, thrust, torque, power, speed, efficiency, loads and safety are excluded.
Change the float count and waterline to explore wheel geometry. Diameter sets the numerical dimensions while the drawing keeps a fixed display size; the animation rate does not represent a specified operating speed.
Rigid radial floats rotate through a partly submerged lower arc
A California State Lands Commission maritime study distinguishes radial and feathering paddle wheels. In the radial type, floats are connected directly to arms radiating from the paddle shaft; the floats are the boards that push the craft through the water.
US Patent 6,264,518 documents a horizontal shaft, spaced hubs, radial spokes and blades that extend downward to engage the water. The animation preserves that rigid wheel geometry and uses the declared immersion only to place a horizontal waterline.
A propulsion topology with many design-dependent outcomes
The cited California study reports radial wheels on sternwheelers and many other paddle-wheel craft, while feathering wheels use linkages to control float orientation. The patent documents a stern-mounted radial paddle-wheel arrangement and an embodiment that can raise or lower the wheel to change engagement depth.
Those sources support the topology, not universal performance bands. Vessel hydrodynamics and machinery selection require a specific design and qualified naval-architecture analysis.
Declared circle and equal-spacing identities
D, k and N are declared inputs. The immersion depth is measured vertically from the waterline to the wheel's bottom tip; it is not a recommendation.
Declared geometry example
For D=3.0 m, k=15% and N=8, radius is 1.500 m, ideal circumference is 9.425 m, declared bottom-tip immersion is 0.450 m and equal float spacing is 45.00 degrees.
No thrust, slip, RPM, boat speed, torque or power follows from those geometric identities.
What geometry alone cannot determine
Actual paddle-wheel behavior depends on float size and shape, immersion through waves and trim, hull wake, wheel speed, vessel speed, entry and exit losses, ventilation, structural stiffness and drive losses. A static immersion percentage is not an efficiency curve.
Choosing an operating immersion and wheel speed requires the float geometry, vessel conditions and drive characteristics. The entered immersion percentage is a geometric setting, not a recommended operating point.
Radial paddle-wheel questions
Is the entered immersion an optimum?
No. It is only a declared geometric waterline.
Does float count predict smoothness or thrust?
No.
Why does the animation keep every float radial?
That is the defining geometry of the radial type described by the cited maritime study.
Does circumference equal distance advanced per revolution?
No; real water interaction includes slip and losses.
Can this calculator size a vessel or drive?
No.
Radial paddle-wheel references
- California State Lands Commission, Sacramento River Shipwrecks: government maritime study distinguishing radial and feathering wheels and defining floats mounted directly on radial arms.
- US Patent 6,264,518, Paddle wheel boat: horizontal shaft, hubs, radial spokes, blades engaging the water and adjustable immersion embodiment.
- Library of Congress, The Paddle-Wheel as an Instrument for Propelling Boats or Vessels: digitized historical treatise on paddle-wheel propulsion.
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