How to describe the sea state
The performance of a sailing boat is affected by the presence of surface waves. In order to understand the boat's behavior under these conditions, it …
Wind-generated sea waves
Wind-generated waves occur when the wind blows over the surface of the sea. They are divided into gravity waves (wind sea, and swell) and capillary wa…
Hull appendages, planforms, and wing sections: what are they?
Fin keels and rudders have become the standard configuration nowadays for racing and cruising yachts and everything in between, be it inshore or offsh…
Wind triangle
The wind experienced by a fixed observer (true wind) is not the same wind an observer on a moving yacht will feel (apparent wind). The wind triangle h…
Points of sail
The points of sail refer to the course a boat is sailing in relation to the wind. They are defined in reference to the wind angle, which is the angle …
What the hydrodynamic resistance is and why it matters
The motion of a sailing yacht through water requires energy to overcome resistance. It is essential to know the mechanisms behind the generation of th…
The air-water interface
Water and air are two different fluids that enter into contact at the ocean's surface at what is called the air-water interface. This interface plays …
Surface waves
Surface waves are created by disturbance forces applied to a specific area. It can be either the wind, a surface vessel moving through the water, an e…
What is the Froude number?
The Froude number is a dimensionless number used to quantify the influence of gravity on the motion of a fluid. It is the ratio of the inertia forces …
The evolution of hull and keel forms – Part 2
British "plank-on-edge" suffered from poor form stability. Yet, the deep down located ballast offered a considerable amount of weight stability and po…
The evolution of hull and keel forms – Part 1
Until the 19th century, the art of yacht design had been mainly influenced by tradition, economic and commercial motivations, understanding of materia…