The meaning of circulation
Circulation is one of the most misunderstood terms in sailing. Yet, circulation is essential to understand lift and why sails, wingsails, keels, rudde…
Hydrodynamics
The Reynolds number
The Reynolds number is the ratio of inertia forces to viscous forces involved in the flow. Reynolds understood that while inertia forces were dominant…
Understanding the boundary layer
In 1904, Ludwig Prandtl introduced an approach to understanding and analyzing flows around bodies that produced a massive breakthrough: the boundary l…
Bernoulli’s principle
The physical significance of Bernoulli's equation is what is known as Bernoulli's principle. It states that when the velocity of a fluid increases, th…
Flows in sailing
Sailing boats interact with flows of two very different fluids: air and water. Moreover, sailing boats are able to make their way through the water su…
Added resistance in waves: “Pinkster” solver versus “Keuning 2006” comparison
In 1980, Johannes Albert Pinkster defended his doctoral thesis "Low frequency second order wave exciting forces on floating structures". His work focu…
Added resistance in waves of a yacht (calculation)
See also: Added resistance in waves knowing yacht’s radius of gyration (calculation). Added resistance in waves: Response Amplitude Operator (calculation). What the hydrodynamic resistance is…
Added resistance in waves knowing yacht’s radius of gyration (calculation)
Calculation template How does it work? The calculation requires LWL, Tc, BWL, ∇c, CP, the yacht’s radius of gyration, Kyy, as well as the significant…
Added resistance in waves: Response Amplitude Operator (calculation)
How it works When sailing against waves, a sailing craft experiences an additional resistance that penalizes its performance. To study how the boat is affected,…
Wave spectral density (calculation)
The performance of a sailing boat is affected by the presence of surface waves. To understand the boat’s behavior under waves, it is necessary first…
Viscous resistance of the rudder (calculation)
Viscous resistance of the rudder (advanced calculation)
Pressure resistance of the rudder (calculation)
Pressure resistance of the rudder (advanced calculation)
Frictional resistance of the keel (calculation)
Frictional resistance of the keel (advanced calculation)
Frictional resistance of the rudder (calculation)
Frictional resistance of the rudder (advanced calculation)
Total residuary resistance of a boat or yacht (calculation)
Total residuary resistance of a boat or yacht (calculation)
Residuary resistance of the keel upright and heeled (calculation)
Residuary resistance of the keel upright and heeled (calculation)