A watersports boat includes a hull having an underside extending from a forward bow to an aft transom along a longitudinal centerline. The underside defines a running surface that contacts water when the hull moves therein. The running surface includes a bow section and port and starboard midship running surface sections that flatten moving aft to an aft running surface section. The port and starboard midship running surface sections are separated by a keel member. The keel member has an apex lower than the aft running surface section and that inclines toward the aft running surface section aft the apex and forward a propeller positioned beneath the aft running surface section.

A watersports boat includes a hull having an underside extending from a forward bow to an aft transom along a longitudinal centerline. The underside defines a running surface that contacts water when the hull moves therein. The running surface includes a bow section and port and starboard midship running surface sections that flatten moving aft to an aft running surface section. The port and starboard midship running surface sections are separated by a keel member. The keel member has an apex lower than the aft running surface section and that inclines toward the aft running surface section aft the apex and forward a propeller positioned beneath the aft running surface section.

A shape shifting foil alters the shape of a fluid foil contour by rotating a leading edge structure. A skin that forms the fluid foil contour is at least partially attached to the leading edge structure, and is wrapped around the leading edge structure so two edges of the skin form the trailing edge of the fluid foil. The two edges forming the trailing edge slide with respect to one another, thereby permitting the skin to shift when the leading edge structure is rotated.

A shape shifting foil alters the shape of a fluid foil contour by rotating a leading edge structure. A skin that forms the fluid foil contour is at least partially attached to the leading edge structure, and is wrapped around the leading edge structure so two edges of the skin form the trailing edge of the fluid foil. The two edges forming the trailing edge slide with respect to one another, thereby permitting the skin to shift when the leading edge structure is rotated.

A motile buoyancy apparatus for use in a fluid. The motile buoyancy apparatus includes an outer layer, the outer layer having a performance surface. The motile buoyancy apparatus includes at least a portion including a first material. The first material is a non-Newtonian material. The at least a portion causes the performance surface to exhibit a shear rate-variable shear response.

A flexible steering fin and passive cambering keel for sailboats having fundamental simplicity yet enhanced performance and superior operation in terms of design and components. The steering fin is a relatively short and elongated flexible blade with its leading edge fixed beneath the hull. A rod passing through the hull functions as a simple lever controlling the trailing edge of the blade, which provides both tilt and curvature for unique handling and ease of use. A separate flexible keel provides the function of tilting the keel as it is cambered, for greater lift. A unique pivoting resilient steering assembly is incorporated, along with a rotational circular hull section, frame and cam assembly to control the keel.

A flexible steering fin and passive cambering keel for sailboats having fundamental simplicity yet enhanced performance and superior operation in terms of design and components. The steering fin is a relatively short and elongated flexible blade with its leading edge fixed beneath the hull. A rod passing through the hull functions as a simple lever controlling the trailing edge of the blade, which provides both tilt and curvature for unique handling and ease of use. A separate flexible keel provides the function of tilting the keel as it is cambered, for greater lift. A unique pivoting resilient steering assembly is incorporated, along with a rotational circular hull section, frame and cam assembly to control the keel.

An engine room arrangement for a marine vessel comprises a fin formed at a rear portion of a hull of the vessel. The fin projects downward from the hull and protects a propeller of the vessel. A gear box is arranged at least in part in the fin and transmits a rotation of a propulsion shaft coupled to a main engine to a propeller shaft drivably coupled to the propeller. The fin provides extra buoyancy for the vessel. The propeller shaft is formed as a relatively short shaft, while the propulsion shaft is formed as a high speed/low torque shaft having a smaller diameter.

An engine room arrangement for a marine vessel comprises a fin formed at a rear portion of a hull of the vessel. The fin projects downward from the hull and protects a propeller of the vessel. A gear box is arranged at least in part in the fin and transmits a rotation of a propulsion shaft coupled to a main engine to a propeller shaft drivably coupled to the propeller. The fin provides extra buoyancy for the vessel. The propeller shaft is formed as a relatively short shaft, while the propulsion shaft is formed as a high speed/low torque shaft having a smaller diameter.

This invention provides a water craft hull having an air chamber, wherein the sidewalls of the air chamber extend lower than the fore wall and the aft wall of the air chamber, and wherein the hull comprises at least one air injector configured to deliver pressurized air to the air chamber. Optionally, a hull of the invention has a high aspect ratio air chamber defined by a stable fore wall, a stable aft wall, and stable sidewalls, is a non-planing hull, has a wave-piercing bow, and has elongated keel fins (e.g. inner keel fins and/or outer keel fins). Optionally, the air chamber is configured for recirculating air flow.