The present invention provides an eco-friendly underwater buoy and a manufacturing method therefor, the underwater buoy comprising: a liner main body of which the inside is hollow; a winding member which is melt welded on the outer surface of the liner main body by winding, and which absorbs external shock; and buoy couplers embedded in both ends of the liner main body so as to couple adjacent underwater buoys to each other. The present invention winds, through filament winding, a wire, in which a glass fiber, a resin and the like are mixed, around the outside of a liner structure so as to manufacture an underwater buoy, and thus, since the underwater buoy is made of a composite material, the appearance of the buoy structure can be stably maintained for a long time without damage caused by various underwater shocks, so that underwater environmental pollution caused by buoy structure damage can be minimized, thereby maximizing the eco-friendliness of the underwater buoy.

A method of manufacturing marine riser buoyancy elements includes providing a master mold and mold inserts such that a range of buoyancy elements may be manufactured from one master mold and providing the mold inserts such that an annular space between the riser main conduit and the buoyancy elements, or a groove width between the buoyancy elements may be varied during manufacture.

A buoy comprising: an annular upper portion disposed on a lower portion; a drain hole disposed in the upper portion proximate to the lower portion; a handhold disposed in the upper portion distal to the lower portion; an attachment member disposed in the lower portion and protruding from a bottom of the lower portion, wherein the bottom is opposite the upper portion; and wherein at least one of the upper portion and the lower portion comprises a closed cell foam.

An expansion-molded article that can be firmly heat-fused with another member is provided. The expansion-molded article is one that may be heat-fused with another member, where the expansion-molded article includes at least one protrusion which is formed on at least one surface of the expansion-molded article including at least one surface is to be heat-fused with the another member. The at least one protrusion comprises at least two surfaces as viewed from above, and a boundary line between the at least two surfaces, where the at least one boundary line intersects a direction from an outside of the at least one protrusion toward a center of an apex of the at least one protrusion.

Buoyancy modules (200) are made from a foam composition that includes a combination of a thermally fusable powder and glass microspheres heated in a manner that provides a hardened syntactic foam having both low density and a high degree of compressive strength. An outer barrier (220) may enclose the buoyancy module.

Provided a resilient waterfowl decoy comprising a molded body with an upper side and a lower side, having an interior cavity, the molded body constructed from a non-brittle copolymer; two keels attached to the lower side of the body, each adapted to receive a weight; two weights each sized and shaped to be received by one of the two keels; and a vent port oriented to allow the passage of air from the interior cavity through the molded body.

Buoyancy modules (200) are made from a foam composition that includes a combination of a thermally fusable powder and glass microspheres heated in a manner that provides a hardened syntactic foam having both low density and a high degree of compressive strength. An outer barrier (220) may enclose the buoyancy module.

An eco-friendly buoy includes a foam including a cylindrical accommodation space in the interior of the foam, and coupling grooves at predetermined intervals at an outer surface circumference of the foam in order to fasten the foam to fixing members through wire; and a protective layer formed on an entire outer surface of the foam and protecting the foam from damage by waves or wind. The eco-friendly buoy is manufactured from eco-friendly expanded polypropylene and expanded styrene and has a protective layer on an outer surface thereof, thereby being protected from damage by waves or wind. In addition, the eco-friendly buoy may be used for a long time, thus reducing maintenance costs.

An eco-friendly buoy includes a foam including a cylindrical accommodation space in the interior of the foam, and coupling grooves at predetermined intervals at an outer surface circumference of the foam in order to fasten the foam to fixing members through wire; and a protective layer formed on an entire outer surface of the foam and protecting the foam from damage by waves or wind. The eco-friendly buoy is manufactured from eco-friendly expanded polypropylene and expanded styrene and has a protective layer on an outer surface thereof, thereby being protected from damage by waves or wind. In addition, the eco-friendly buoy may be used for a long time, thus reducing maintenance costs.

An improved flotation device using a molded casing including a concrete lower ballast core section and a foam upper buoyancy core section. A method of construction is taught including forming the casing, installing the core into the casing, transporting the device, and sealing the casing.