A covering system for removably covering a vehicle, such as a boat, that includes a plurality of rotatively anchored swing arms rotatable between a covered position and an uncovered position. Each swing arm includes a mount and a pretensioner formed of one or more stays adjustably attached to part of a shaft of the arm to adjust an applied preload and transfer forces encountered during operation to part of the shaft rotatively anchored by the mount to a grounded structure such as a piling or post of a dock. The swing arms are pivotally connected to an elongate transversely extending carriage from which a cover is suspended with a boom of each arm connected to the carriage by a pivot assembly that also facilitates carriage and cover position adjustment. A pivot limiter can be included that limits or even stops pivoting of the carriage relative to the swing arm boom.