International Measurement System: Sails
The International Measurement System (IMS) is a set of rules that defines what and how is measured on a boat. It is used by the Offshore Racing Congre…
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Challenges in sailboat design
Using wind power and sails as the primary means of propulsion brings additional dimensions to the design of a sailboat compared to ship or powerboat d…
Sea state and wave forecasting
The performance of a sailing boat is affected by the presence of surface waves. To understand how the waves influence the boat's performance, we need …
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 …