MrPenguin - Anchors with metal stocks that can be easily moved to parallel the shank were stowed on deck for some vessels. Without the stock jutting at right angles to the flukes, they could be laid on deck and lashed down. Deep sea cargo ships of the 1900's, eg. Pamir, would stow their anchors on deck once they were clear of the shore. The anchor would be re-mounted on the rail, and be re-shackled to the anchor chain, as the ship neared it's destination.
The earlier style, wooden stock anchors of a 1765 frigate, though, were harder to "de-stock". With the stock still mounted, the anchor would take up a lot of volume on the foredeck, and the flukes or stock would interfere with jib sheets and the working of the guns. The ship would remove the cable from the anchor, once they were in deep water, so that it could be stowed below decks. Stowing the hemp cable protected it against chafe and uv-light, and also gave it a chance to dry out.
John Harland's "Seamanship in the age of sail" delves deeply in to anchor handling, if you wish more information.