Provided is a hull of a boat including a central portion of a bottom of the hull, side portions of the bottom of the hull, lateral to the central portion of the bottom of the hull, the central portion of the bottom of the hull being substantially lowered in a substantially discontinuous way with respect to the side portions of the bottom of the hull, central side walls separating the central portion of the bottom of the hull from the side portions of the bottom of the hull. The hull also having external side walls laterally external to the side portions of the bottom of the hull.

A skeg mounts from the stern of a towing vessel and extends below the waterline. A channel in the skeg protects cables for steamers and a source of a seismic system deployed from the vessel. Tow points on the skeg lie below the water's surface and connect to towlines to support the steamers and source. A floatation device supports the source and tows below the water's surface to avoid ice floes. The streamers can have vehicles deployed thereon for controlling a position on the streamer. To facilitate locating the streamers, these vehicles on the streamers can be brought to the surface when clear of ice floes so that GPS readings can be obtained and communicated to a control system. After obtaining readings, the vehicles can be floated back under the surface. Deploying, using, and retrieving the system accounts for ice at the surface in icy regions. In addition, handling the seismic record can account for noise generated by ice impact events.

A skeg mounts from the stern of a towing vessel and extends below the waterline. A channel in the skeg protects cables for steamers and a source of a seismic system deployed from the vessel. Tow points on the skeg lie below the water's surface and connect to towlines to support the steamers and source. A floatation device supports the source and tows below the water's surface to avoid ice floes. The streamers can have vehicles deployed thereon for controlling a position on the streamer. To facilitate locating the streamers, these vehicles on the streamers can be brought to the surface when clear of ice floes so that GPS readings can be obtained and communicated to a control system. After obtaining readings, the vehicles can be floated back under the surface. Deploying, using, and retrieving the system accounts for ice at the surface in icy regions. In addition, handling the seismic record can account for noise generated by ice impact events.

It is an object of the present invention to reduce a restriction caused by a water depth of an area available for sailing. The ship has a hull part and is configured to be able to sail on water. The hull part has: a fuselage extending in the longitudinal direction of the hull part; a keel and a rudder arranged on the fuselage to receive water flow when the ship sails; a first posture switching mechanism for switching the postures of the keel and the rudder between a first posture and a second posture; and a first power source. The first posture is in the keel and the rudder respectively extending to the lower side of the fuselage. Compared with the first posture, the second posture is shorter in the length of the keel and the rudder when extending toward the lower side of the fuselage.

It is an object of the present invention to reduce a restriction caused by a water depth of an area available for sailing. The ship has a hull part and is configured to be able to sail on water. The hull part has: a fuselage extending in the longitudinal direction of the hull part; a keel and a rudder arranged on the fuselage to receive water flow when the ship sails; a first posture switching mechanism for switching the postures of the keel and the rudder between a first posture and a second posture; and a first power source. The first posture is in the keel and the rudder respectively extending to the lower side of the fuselage. Compared with the first posture, the second posture is shorter in the length of the keel and the rudder when extending toward the lower side of the fuselage.

Catamaran boat hulls are described having sponsons, an underside tunnel surface between sponsons, two longitudinal steps disposed across each sponson's keel, and two transverse steps disposed lengthwise on opposing sides of each sponson's keel. The longitudinal steps for a sponson have a profile with a curved longitudinal step portion on the opposing outer edges with an outer edge portion of that curved longitudinal step portion being further away from the sponson's aft section, and an inward step edge offset where each of the two longitudinal steps meets a hull side of the sponson. The transverse steps help define variable deadrise inner lifting pad running portion with a lower deadrise aft transitioning to a higher deadrise forward. Spray rails protruding off the aft end of an underside wave spitter and away from the boat hull's centerline help manage undesired spray and use of radiused chines enhances lift and landing performance.

Catamaran boat hulls are described having sponsons, an underside tunnel surface between sponsons, two longitudinal steps disposed across each sponson's keel, and two transverse steps disposed lengthwise on opposing sides of each sponson's keel. The longitudinal steps for a sponson have a profile with a curved longitudinal step portion on the opposing outer edges with an outer edge portion of that curved longitudinal step portion being further away from the sponson's aft section, and an inward step edge offset where each of the two longitudinal steps meets a hull side of the sponson. The transverse steps help define variable deadrise inner lifting pad running portion with a lower deadrise aft transitioning to a higher deadrise forward. Spray rails protruding off the aft end of an underside wave spitter and away from the boat hull's centerline help manage undesired spray and use of radiused chines enhances lift and landing performance.

A passively controlled fluid foil has a span; and a rigid spar extending in the spanwise direction, a cellular material and a flexible outer surface defining a profile of the outer surface of the foil and encapsulating the cellular material and the spar.

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.