A kayak holder configurable between an open, load-receiving configuration and a closed, stored configuration can include an elongate support arm and a base. The base can be releasably mountable upon a load bar of a carrying vehicle. The elongate support arm can be anchored to a hub having an axle rotatably coupled to the base. The base can comprise a keyway assembly that releasably receives a mating key assembly on the axle. The elongate support arm can have a locked position where the key assembly is interference-engaged in the keyway assembly and an unlocked position where the key assembly axially displaced from the locked position out of interference-engagement with the keyway assembly. The key assembly can include a key adapted to be located in a keyway of the keyway assembly in the locked position, thereby blocking rotation of the arm relative to the base.