A surfboard includes a core covered with a laminate and having curved perforations in the deck area and the tail area of the surfboard, in order to prevent air blisters from forming between the core and laminate. The curved perforations are deformable under pressure to minimize the opening of the perforations to inhibit liquid from entering and maximizing under zero pressure to allow the maximum amount of trapped liquid and gasses from escaping. The core is formed from an extruded closed-cell polystyrene foam block that has been shaped by restraining it against a shaped form using shaped restraining tools and straps, and heating it; and by cutting using a hot wire. The core is laminated with FIBERGLAS and epoxy resin, and the perforations are formed using a perforating tool that has a planar or curved working surface and one or more heated needles extending perpendicularly from the working surface.

A process and associated system for creating color effects using extrudable material, such as plastic and metal for example, are presented. Flows of first and second viscous materials of respective colors are provided and then combined in a predetermined pattern to form a stream of combined viscous material. A dynamic mixer is the then used to apply a predetermined dividing, overturning and combining motion to the stream of combined viscous material to partially mix the first viscous material and the second viscous material, such that upon exiting the dynamic mixer, the first material of the first color and the second material of the second color form a color pattern in the stream of combined viscous material. The dynamic mixer has elements configured for acquiring a specific radial orientation in a range of radial orientations that may be varied during the application of the dividing, overturning and combining motion to the stream of combined viscous material to cause variations in the color pattern in the stream of combined viscous material. Sheets of extruded material may be created using such process and system and used in the manufacturing of many different products including, but not limited to, kayaks, stand-up paddle boards, garden furniture and many others. In some embodiments, the sheets may be characterized by color bands extending diagonally with reference to a longitudinal extent of the sheet.

Closed cell chitin foam is provided. The closed-cell chitin foam composition does not absorb water, is biodegradable, and is mechanically characterized by a density range of 16 to 800 kg/m3, closed-cell pore sizes ranging from 50 microns to 1 mm, an elastic modulus of 3 to 175 MPa, and a tensile strength of 0.15 to 6.5 MPa. The chitin is at least 70% acetylated. In one aspect, the foam is enclosed in a shell e.g. in the form of a surfboard. Chitin foam according to this invention is fully biodegradable. The chitin foam overcomes the current problems with foams that contain polyurethane and polystyrene, and which are manufactured from petroleum-based sources. Petroleum based foams are not renewable, have an adverse impact on our environment, and pose significant health hazards to those who manufacture them. The chitin foam with its water-based manufacturing process and naturally sourced chitin, solves these problems.

In one example, a board includes a body having a single piece structure, the body including an upper surface that defines a deck, and a lower surface. The board also includes first and second retractable fins, where the first retractable fin is rotatably connected directly to the body at a first fixed location on the body such that the first retractable fin is rotatable about the first fixed location between an extended position and a retracted position, and the first retractable fin including an engagement portion that is engageable with a first portion of the body and with a second portion of the body. The first retractable fin assumes the extended position when the engagement portion is releasably retained by the first portion of the body, and the first retractable fin assumes the retracted position when the engagement portion is releasably retained by the second portion of the body.

A process and associated system for creating color effects using extrudable material, such as plastic and metal for example, are presented. Flows of first and second viscous materials of respective colors are provided and then combined in a predetermined pattern to form a stream of combined viscous material. In a first aspect, the flow rate of the first viscous material is caused to vary over time in order to vary an amount of the first viscous material in the stream. In a second aspect, which may be used alone or in combination with the first aspect, the first and second viscous materials have distinct viscosities to reduce an amount of color blending between the first color and the second color in the stream of combined viscous material. A static mixer may then be used to apply a predetermined dividing, overturning and combining motion to the stream of combined viscous material to partially mix the first viscous material and the second viscous material, such that upon exiting the static mixer, the first material of the first color and the second material of the second color form a color pattern in the stream of combined viscous material. Sheets of extrudable material may be created using such process and used in the manufacturing of many different products including for example kayaks and stand-up paddle boards.

A process and associated system for creating color effects using extrudable material, such as plastic and metal for example, are presented. Flows of first and second viscous materials of respective colors are provided and then combined in a predetermined pattern to form a stream of combined viscous material. In a first aspect, the flow rate of the first viscous material is caused to vary over time in order to vary an amount of the first viscous material in the stream. In a second aspect, which may be used alone or in combination with the first aspect, the first and second viscous materials have distinct viscosities to reduce an amount of color blending between the first color and the second color in the stream of combined viscous material. A static mixer may then be used to apply a predetermined dividing, overturning and combining motion to the stream of combined viscous material to partially mix the first viscous material and the second viscous material, such that upon exiting the static mixer, the first material of the first color and the second material of the second color form a color pattern in the stream of combined viscous material. Sheets of extrudable material may be created using such process and used in the manufacturing of many different products including for example kayaks and stand-up paddle boards.

A watercraft has a hull which, in the area of the deck, has a support on which parts of the upper body of a user can rest and where the user can hold on to handles. A flow channel is defined on the hull and a propelling screw is disposed in the flow channel. The flow channel has an intake port and, downstream of the propelling screw, a jet outlet in the stern area. A support body is disposed on the stern area in such a way that the support body extends the support by means of its support surface. In such a watercraft, a considerable increase in traveling speed can be achieved if provision is made for at least one sliding surface to be provided on the underside of the support body and for the support body to be rigidly connected to the hull.

A watercraft has a hull which, in the area of the deck, has a support on which parts of the upper body of a user can rest and where the user can hold on to handles. A flow channel is defined on the hull and a propelling screw is disposed in the flow channel. The flow channel has an intake port and, downstream of the propelling screw, a jet outlet in the stern area. A support body is disposed on the stern area in such a way that the support body extends the support by means of its support surface. In such a watercraft, a considerable increase in traveling speed can be achieved if provision is made for at least one sliding surface to be provided on the underside of the support body and for the support body to be rigidly connected to the hull.

A surfboard having a core, a first elongate spring member located adjacent an upper side of the core, and a second elongate spring member located adjacent a lower side of the core, wherein the first elongate spring member extends substantially from a nose portion of the surfboard to a tail portion of the surfboard.

A surfboard having a core, a first elongate spring member located adjacent an upper side of the core, and a second elongate spring member located adjacent a lower side of the core, wherein the first elongate spring member extends substantially from a nose portion of the surfboard to a tail portion of the surfboard.