Portable spa cover

A pool cover comprising:

• first and second cover halves, each having a lower surface and an upper surface;
• rib means formed in the lower surfaces of the respective cover halves for strengthening the respective halves;
• and
• hinge means for interconnecting and retaining the respective cover halves in horizontal relation with one another while permitting engagement and disengagement of the cover halves when one is raised with respect to the other by an acute angle to the horizontal.

Cover apparatus comprising:

• a first rigid molded cover section having a first edge;
• a second rigid molded cover section having a second edge;
• hinge means for pivotally interlocking said first and second sections along the respective first and second edges;
• and
• said first and second sections each including an upper surface and a lower surface and a plurality of ribs defined by a bell-shaped contour in said lower surface, each bell-shaped contour including a plurality of dome-shaped upward contours therein.

In a cover apparatus, the structure comprising:

• a first rigid, single-piece molded section having an upper surface, a lower surface, and a first edge, said upper surface, lower surface, and first edge defining an enclosed hollow interior space;
• a second rigid molded section having an upper surface, a lower surface, and a second edge, the upper surface, lower surface, and second edge defining a second enclosed interior space;
• and
• a plurality of support structures in each of the first and second rigid molded sections, said support structures each including an upward impression of the respective lower surface into the respective interior space of each of said first and second sections, each said impression comprising a linear groove of uniform cross-section, each said linear groove projects upwardly to contact said upper surface at a plurality of locations.