Abstract: A flexible tarpaulin is rolled about a drum mounted on an axle that is secured to a rigid deck by mounting brackets. A spring acting between the axle and the drum serves to retract the tarpaulin onto the drum. A releasable retraction lock may be used to prevent retraction. The tarpaulin has apertures spaced along its edges and a plurality of fasteners are employed having latching pins that extend through the apertures into anchors embedded in the deck to secure the tarpaulin over the pool.