Waterline Length (LWL)
Also known as: Length at Waterline, waterline length
Length at Waterline. The length of a sailing yacht measured at the water surface when at its designed displacement. LWL is a more accurate predictor of hull speed and performance potential than LOA, as it reflects the portion of the hull actually in contact with water.
Related Terms
LOA
Length Overall. The maximum length of a sailing yacht from the forward point of the bow to the aftermost point of the stern, including any bowsprits or stern extensions. This is the most commonly cited length specification and is used for registration, marina fees, and many regulations.
Dimensions
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
Displacement
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.
Technical
Beam
The maximum width of a sailing yacht measured at its widest point. A wider beam generally provides more interior space and initial stability but can reduce performance in rough seas and increase windage. Modern cruising yachts often have beams around 35-45% of their LOA.
Dimensions
Draft
The vertical distance from the waterline to the lowest point of the keel, also known as the yacht's keel depth. Shoal draft yachts (under 1.5m) can access shallow coastal waters and anchorages but may sacrifice upwind performance and stability compared to deeper draft designs.
Dimensions
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