hulform

Hulform is a rarely used variant spelling of hull form, a term in naval architecture and marine design that denotes the external shape of a vessel's hull. The hull form describes the geometry that determines how the hull interacts with water, including its waterlines, cross-sections, and overall longitudinal lines.

The hull form influences resistance and propulsion, stability and buoyancy, seakeeping, and payload efficiency. Designers optimize the hull form to balance speed, fuel consumption, handling, and comfort for a given mission profile. Changes to the hull shape can alter flow patterns, wave-making resistance, and righting moments, affecting overall performance.

Key parameters used to characterize a hull form include length overall (LOA), length on the waterline (LWL), beam, draft, and hull coefficients such as the block coefficient and prismatic coefficient. Other important features are the keel line, stem and stern shapes, transom or stem configurations, waterplane area, and the distribution of volume along the hull. Evaluation methods typically combine model testing in towing tanks with computational fluid dynamics (CFD) simulations and, in some cases, full-scale trials.

Hull forms are commonly categorized by operating regime: displacement hulls aim for efficient cruising at modest speeds; planing hulls are designed to achieve high speeds by riding on a thin layer of water; semi-displacement hulls mix characteristics of both. In addition, hull forms may be monohulls or multihulls, with various configurations to optimize stability, load-carrying, and maneuverability.

In practice, the standard term is hull form; hulform may appear as a typographical variant or older usage and is not widely recognized in contemporary nautical engineering.