A retractable boat top device is disclosed having an arched canopy assembly operatively deployed in mounted attachment upon a conventional radar arch or like elevated structure on the deck of a boat. The arched canopy assembly includes a stationery roof section formed having a curved planar surface transversely mounted within the radar arch, a pair of telescoping extension arms mounted on opposite sides of the roof section, and an arched roller assembled to hold a flexible canopy material thereon and operatively connected between the outer ends of the extension arms so that the flexible canopy material may be extended and retracted relative to the stationery roof section in an arched configuration substantially in the same plane as the roof section. The arched roller includes a curved roller bar supported coaxially within the bore of a flexible hose member that supports the canopy material in a rolled-up state and further includes torsion spring members mounted along opposite sides of the roller bar to maintain tension upon the canopy material during roll-out and retraction.