Displacement
Also known as: displacement weight, boat weight
The weight of the water displaced by a sailing yacht, which equals the yacht's total weight. Measured in tonnes or kilograms. Heavier displacement (diesel, steel, or heavily built) provides more comfort in rough seas and storage capacity but reduces acceleration and top speed compared to lighter displacement designs.
Related Terms
Ballast Ratio
The ratio of a yacht's ballast weight to its total displacement, expressed as a percentage. A typical cruising yacht has a ballast ratio of 30-45%, while performance-oriented designs may exceed 50%. Higher ballast ratios generally indicate a stiffer, more stable boat, though hull form and center of gravity also matter significantly.
Technical
Hull Speed
The theoretical maximum speed of a displacement hull sailing yacht, calculated as approximately 1.34 × √LWL (where LWL is in feet, speed in knots). Beyond this speed, wave drag increases dramatically. Light displacement, planing, or semi-planing hulls can exceed traditional hull speed limitations.
Performance
Ballast
Weight placed low in a sailing yacht, typically in the keel, to provide stability and prevent capsizing. Modern yachts use lead or iron ballast, often shaped as a fin bulb or in a winged configuration. The ballast ratio (ballast ÷ displacement) is a key indicator of a yacht's stiffness and safety.
Technical
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