Displacement Hull and Semi-Displacement Hull

boatlinessmallBlue Water Cruising

Displacement hulls are well suited for rough, offshore seas and ocean crossings. Because of their design, these hulls can carry large payloads of fuel and water, which make them ideal for long range cruising.

Passage makers use the low power demands of displacement hulls to their advantage. Little driving force is needed to move one of these boats until the hull speed is reached. the hull goes through the water without ever raising up to plane off. Making this hull the most fuel-efficient desired for trans-oceanic crossings.

Displacement hulls are often rounded and would be termed round bottom hulls. A round bottom powerboat has little or no discontinuity in the curve of its section between the gunwale and keel. A round bottom provides a soft ride at the hull speed.

Semi-Displacement Hull

Local, Coastal and Island Cruising

Semi-displacement hulls are designed to operate economically at low speeds while still able to attain efficient planing speed performance.

Flat bottom hulls have defined corners called “chines” where the sides of the hull meet the bottom. Semi-displacement trawler style hulls combine round bottom sections forward and flat bottom sections aft.

Pushed above hull speed, this design operates as a semi-displacement hull. The bow rises out of the water giving more speed to the boat. Faster semi-displacement hull vessels come equipped with larger horsepower engines, normally turbocharged. These hulls are not designed for the performance required for trans-oceanic voyages.

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