“Batten down the hatches – quick, men!” 1883 Chambers Journal
“They battened down the hatches but the hatches wouldn’t hold!” From the song Tempest by Bob Dylan
Sailing ships of old had openings in the deck that were called ‘hatches’ or ‘hatchways’. They could be open or have wooden gratings covering them that permitted air flow in the lower decks. During stormy weather the hatches would be covered with tarpaulin which was edged with wooden strips that were called ‘battens’. The battens stopped the tarpaulins from blowing away. Thus sailors termed this ‘battening down’.